Delaunay Triangulation of Parallelepiped

Question: Given $n$ linearly independent vectors $v_1, v_2, \ldots, v_n$ in $n$-dimensional space. Let $V$ be the set of $2^n$ points of the form $x_1 v_1 + x_2v_2 + \ldots + x_nv_n$, in which $x_i$ can be $0$ or $1$. $V$ is the set of vertices of an n-dimensional parallelepiped. Is there any way to find the Delaunay triangulation of $V$ using subexponential space with respect to $n$? I understand that the size of the output is big, and we can't store the whole output. But is there any way to output the Delaunay edges one by one without storing the previous result?
Answer: Testing whether a pair of points $p_i$ and $p_j$ are the endpoints of a Delaunay edge can be solved as a linear programming feasability problem: Lift each point to one higher dimension by making its last coordinate be the sum of squares of the other coordinates. Then look for a hyperplane passing through $p_i$ and $p_j$, such that all the other points are on one side of it. This can be represented in linear inequality constraints by seeking a vector $v$ and scalar $c$ such that the dot product of $v$ with each point is at least $c$, and is exactly $c$ in the case of $p_i$ and $p_j$.
So for any set of points in any dimension, it's possible to find the Delaunay edges one by one, by solving a number of linear programs that is polynomial in the number of points. The reason Delaunay triangulation is hard is not because of the edges, it's because there may be too many higher-dimensional features.
Comment: Oh, I see what you mean. The ellipsoid method for linear programming runs in polynomial time given only a separation oracle (a black box that can tell whether a point is inside or outside the feasible polytope, and if outside returns a separating hyperplane). See "Geometric Algorithms and Combinatorial Optimization" by Grötschel, Lovász, and Schrijver. And in the parallelotope case, such an oracle is easy to implement in low space — just loop through all the parallelotope vertices testing each one. So I think the answer is yes, this same algorithm runs in polynomial space in terms of n.
Comment: Thanks David. The idea of lifting point to one higher dimension is interesting. By the way, I have another question. Is it possible to find all Delaunay edges in $2^{O(n)}$ using subexponential space?
Comment: The idea of lifting to one dimension higher is extremely standard when working with Delaunay triangulations. And I'm confused by your followup question: doesn't the algorithm I just described find them all in polynomial time and polynomial space?
Comment: it's definitely in polynomial time and space with respect to the number of points. Here we have $2^n$ vertices given by $n$ linearly independent vectors, and I ask for an algorithm running in subexponential space in $n$. If it's possible to solve a linear programming of $2^n$ inequalities in $2^{o(n)}$ space then your algorithm will works. But then the running time will probably be bad, so I wonder if it's possible to find an algorihm that runs in $2^{O(n)}$ or not.
Comment: I'm thinking of doing gift wrapping in $n+1$ dimensions, since we don't have to store previous results with gift wrapping. If we can somehow bound the number of open ridges, then the space would not be too big.


Add site to trusted sites through GPO

Question: I need to add a site to trusted sites on all computers in my domain. I can do it with the "site to zone assignment list", however when I do, it locks trusted sites on the client computer "this setting is managed by your administrator".
What I need is a way to add the site, make it persistant, and not affects the users ability to add trusted sites of thier own. (It's a development enviroment, sites are created and tested regularly, they need that ability.)
Answer: If you use logon scripts you could push a .reg file that has the trusted sites in there...that way you're not using the GPO to "take control".
Something similar is described here: http://nefaria.com/2009/10/adding-trusted-sites-for-ie-via-the-registry/
Also, if you don't want to replace what a user has already entered, there is a syntax to "append" data to a registry key...that way you can just add a global list but not wipe out individual additions already made by a user.
Here is some registry editing syntax : http://msdn.microsoft.com/en-us/library/aa371168%28VS.85%29.aspx
Comment: I was hoping to avoid using logon scripts... GPO is so much cleaner. Can I stealth the script so its transparent to the user?
Comment: You could use VB instead of a batch file and make the script invisible to the user...if you're more proficient with batch files you can use GPO to Run Legacy Logon Scripts Hidden.
Comment: Your statement that GPO is cleaner than Logon scripts makes me think that you don't really understand either one. A Logon script can and should be configured in a GPO, not on the properties of the user account. By default Logon scripts called from a GPO run hidden.
Answer: Assuming you have WinNT6 clients (Vista / Win7 / Win8), use a Group Policy preference setting to add the REG entry.  Preference settings do not restrict the user's UI.  Job done.
See Registry Extension TechNet Article for more info.

Add site to trusted sites through GPO


How do I quit Meta?

Question: I want to remove my account from Meta. How can I do that?
Comment: Just... stop coming here?
Comment: Well, I want to wipe the history of hateful comments on my posts on meta and the posts themselves and in general disassociate myself from the meta community. Isn't there a right to be forgotten on here? :)
Comment: You can have the posts disassociated from your account, delete them if they don't have upvoted or multiple answers, flag offensive or unhelpful comments; same stuff you usually can.
Comment: Delete the entire parent community and start over.
Answer: To clarify because there's a lot of misinformation here: We can delete your Meta profile only. However:

It is still subject to the 24-hour countdown period before the deletion occurs, like on main sites.
Deleting your Meta profile is a bit of a fruitless effort because it is always automatically recreated for you the moment you visit Meta for any reason while logged into your main account. And no, there is no way to prevent that automatic creation from occurring.

If you don't want to be associated with specific questions, request disassociation using the contact us form. Otherwise, your only option is to just not visit, or don't do anything if you have to visit. We're not going to keep deleting your profile here every time it gets recreated for you. By the same token, don't go losing your temper here every day and then asking for disassociation - there's a more expedient solution to such problems that will eventually occur to us.
Comment: @TylerH No. Posts get anonymized the same way they do on main sites. But disassociating is plain faster than going through the entire deletion process if that's the true desire.
Comment: If he has his meta account deleted, and then re-visits meta, will the newly created account have all his old content from before it was deleted?
Comment: @animuson There's one caveat: if any of the posts were migrated to meta, they'll get remapped to the new account all over again. (This is another reason to disassociate rather than delete the user.)
Answer: Click the "contact us" link at the bottom of any page and send us a request for deletion.
Given meta deletion is so unusual, you'll have to choose "Other" and write out what you want; if you choose "I need to delete my user profile", it'll just give you an error.
Comment: If there's one thing meta users know like the backs of their hands, it's rage quits.
Comment: This is like a [javascript] question, 4 answers within a minute of eachother.
Comment: For the sake of reference: [List of already deleted ragequits mixed with downvote rants (requires that your username ends with a diamond)](http://meta.stackoverflow.com/search?q=downvotes+deleted%3A1+score%3A...-10)
Answer: The only way I can think of to remove your Meta Stack Overflow account is to delete your Stack Overflow account- The two are tied together and I'm unsure if the team can delete one but not the other. Two members of the Stack Overflow team have stated that this is incorrect.
To hopefully address a little of why you'd like your Meta account removed:
Meta is a bit different of a beast than Stack Overflow Main. Questions and answers tend to get more attention, as less questions hit Meta per day. There's also a smaller group of frequent users on Meta than Main. If your question is poorly researched, a duplicate, or a rant, it is incredibly likely to be found out.
If you wish to delete your Meta account because of the downvotes on three of your four (visible) Meta questions, I really wouldn't worry about it. Downvotes on Meta are different. They can mean the same things they mean on Main, but they can also be opinions of the thought, feature, or premise of the post. This is especially true of feature requests, but the mentality does extend to anything that suggest a feature or has a premise a lot of users (dis)agree with.
Under the assumption that you do not want to delete your account, I would suggest not contributing to Meta for a while. If you do want to contribute in the future, or think that you'll want to, perhaps lurk on Meta in the intervening time. It can help you not only get a feel for the differences between the two sites, but also help you see what helps make good posts on Meta.

How do I quit Meta?


How to get rid of goitrogens from goitrogenic foods without cooking?

Question: Cruciferous vegetables like cabbage, Brussels sprouts, broccoli, broccolini, cauliflower, mustard greens, kale, turnips, and collard greens contain goitrogens. Is there a way to get rid of these without cooking. I eat those vegetables daily in salad.
Comment: We don't answer questions regarding health claims, so I removed the health-related parts from your question.
Answer: Gamma Radiation... not practical, but it would inactivate the enzyme that leads to goitrogenic activity in most Brassicae.  The majority of these vegetables are really only very slightly goitrogenic because the possible thyroid inhibiting substance, goitrin, is bound up in progoitrin, an inactive compound.


When did we know the color/appearance of all the planets in our solar system?

Question: When did we discover the color/appearance of all the planets in our solar system? Was this process spread out over a long period of time?
Comment: @MarkC.Wallace We usually discovered them as tiny moving dots, or a few pixels. To counter that, [here's what Pluto looked like when it was discovered in 1930](https://en.wikipedia.org/wiki/Pluto#/media/File:Pluto_discovery_plates.png) and [here's the best we had from Hubble](https://en.wikipedia.org/wiki/File:Pluto_animiert_200px.gif) until New Horizons. (And no, I don't want to argue whether Pluto is a planet. I'm using it as a convenient example.)
Comment: I don't think I understand the question - we discovered the color/appearance of each planet when we discovered the planet - this is well documented in any basic reference source.  The visible planets have been known since antiquity (hence "visible planets").  What is it you want to know that is beyond a simple google search> (Not trying to insult, trying to make sure we're answering the right question.)
Answer: Vector site provides a nice summary of what we know about the planets. That will be the source for my answer.
Some planets were fairly well known to the ancients, but they could only use their eyes until the birth and proliferation of the telescope (starting in the 1600s) and then modern telescopes and space probes (1900s).
The planets known to the ancients were Mercury, Venus, Mars, Jupiter and Saturn.  Of these, Venus and Mars could be more closely observed by the eyes (with Mars appearing red), but Jupiter and Saturn appear as brighter distant stars.  However, they had a clear orbit and so they fell into the "planet" category. Even the closer planets are confusing to the eye - Mercury and Venus are low in the atmosphere and/or coincide with the sun, making it hard to see any detail with the eye.
Telescopes from the 1600s into the early 1900s could only tell so much. Using math and orbital mechanics, combined with telescope observations, astronomers could determine relative density, mass, orbital parameters and so on. Prominent moons could be seen too: Galileo spotted four moons with his first observation of Jupiter in 1610.
The more distant planets required stronger telescopes. Uranus wasn't spotted until the 1780s and its rings weren't spotted until 1977.
Understanding of Uranus' orbital mechanics developed in the 1800s to suggest the presence of another planet, and so astronomers started looking. With the latest understanding of Uranus' strange orbit and some math, Le Verrier plotted the position of what had to be the source of the issue - and thus Neptune was found in 1846. Galileo had actually spotted Neptune in 1613 but chalked it up to a star. Neptune's first moon Triton was spotted shortly afterward, but appeared so small and faint as to be hard to calculate its properties.
Pluto wasn't spotted until 1930. I'll avoid the planet debate here, but information about Pluto was slow to come and difficult to interpret. Charon, which defines some of Pluto's behavior and being unusual as a binary system, wasn't found until 1978.
Telescopes could also be misleading. The most famous case is Mars' canals. The presence of canals, which appeared to link oceans or oases, appeared in observations in the 1800s. Giovanni Schiaparelli produced a map of Mars in 1877 that showed them prominently. The canals and their possible origins captured the imagination of astronomers and the sci-fi community for years, although other astronomers claimed they couldn't see them. This craze included a book, MARS AND ITS CANALS, by Percival Lowell in 1906. When Mariner 4 observed Mars in 1965, there were no canals or oases - just a barren planet.
The limits of classic telescopes started to be reached in the late 1800s. For example, the fifth known moon of Jupiter would be observed in 1892 and would be the last until photography and imaging technology (i.e., modern telescopes) became useful. Radar astronomy would provide additional data and would correct some previous observations, such as showing Venus to be very hot in the 1950s (previously Venus was thought to be swampy).
Most of these earth-based observations were still relatively basic by the 1960s.
Space probes had to clarify and confirm many of these observations, starting in the early 1960s with simple probes. For the gas giants, Pioneers 10 and 11 were the first visitors but were fairly basic, but the soon-to-follow Voyagers provided fantastic data that added much to what is now known - although there are still plenty of mysteries out there.  Earth-based observatories still play a prominent role as well.
To summarize the answer, only a few planets had color and appearance that could be estimated and guessed until relatively recently. The telescope certainly helped starting in the early 1600s, but there were still errors and limitations (the Mars canal controversy being an example). Earth-based observations have expanded our knowledge but are concerned more with physical properties (mass, density, spin rates, atmospheric parameters, etc).  Space probes have been the best at determining color and appearance.
Comment: @Smith The colour of gaseous planets _is_ the colour of the atmosphere, not the colour of the core.
Comment: @DavidRicherby: Multi-spectral observation is a powerful tool in observation but would it give you the color of the dirt on Uranus, as what I thought the OP was asking?  Spectroscopy will help you investigate the composition and volume of the atmosphere, makeup of the crust, spin rate, occultation phenomenon, thermal characteristics, magnetic field, and so on, leading to calculations of density, core make-up, and so on.
Comment: @MAGolding: Ah, humans at work. Something was in orbit with them all along and they never recognized it for what it was. Despite being historically close observers of the stars, the eyeball can only do so much.  You need better optics, good math, and communication with other astronomers to get somewhere, and you see this start to yield results in the 1700s and 1800s.
Comment: @ Smith Uranus is visible to the naked eye as a very dim star.  It has thus been seen countless times.  If anyone had noticed it enough to plot its position and recheck it some time later they would have noticed it had moved.  Thus Uranus could have been discovered as a moving planet thousands of years earlier.
Comment: FYI: The "canals" were a mis-translation from italian into english, paired with the hype around the Suez canal, c.f. https://www.nasa.gov/audience/forstudents/postsecondary/features/F_Canali_and_First_Martians.html - it was Lowell who described them as artificial, not Schiaparelli.
Comment: Actually, Jupiter can appear brighter than Mars at their closest approaches.
Comment: I'm not at all convinced by your last sentence. [Section 17.2 of the page you link](http://vc.airvectors.net/tampl_17.html#m2) is entitled "Neptune before the space race" and refers to "spectroscopic studies" in 1975, which is long before Voyager 2 passed by: spectroscopy is entirely about knowing what colour things are in huge detail.
Comment: @jamesqf Yes, I noticed it was particularly bright earlier this month. [According to this really neat brightness tool](https://www.timeanddate.com/astronomy/planets/distance) (lower numbers are brighter), Jupiter is usually around -2, being a fairly steady distance away and very large, while Mars goes between -2 and 2 as it gets nearer and closer to the Earth.
Answer: tl;dr
If we define "color" as true visible light color and "appearance" as being able to make out surface features, that just leaves "planet".
If we include Pluto, 2015 when New Horizons flew by Pluto.
If we don't include Pluto, 1989 when Voyager 2 flew by Neptune. For many of the outer planets the Voyager Grand Tour missions were the first really good images we got.

Because of the ambiguity about "planet", the answer depends on when you ask and what you believe are planets. If you asked up until 1989 the answer would be "we don't have good images of Neptune and Pluto yet". If you asked after the Voyager 2 fly-by of Neptune in 1989, but before Pluto's demotion in 2008, the answer would be "we don't have good images of Pluto yet". After Pluto was demoted to a dwarf planet in 2008 the answer retroactively became "1989". And if we find the hypothesized Planet Nine the answer will go back to "we haven't seen all the planets yet". Weird.
All this absurdity comes down to what is a "planet" and that we keep discovering new ones. Also what it means to "know" its color and appearance. These are arbitrary definitions. Let's get "planet" out of the way first. It's the most contentious, and also of the most historical relevance.
"Planet"
Prior to the 21st century, there was no formal definition of a planet. And what is and is not a planet has changed over time. There is a pattern through history of deciding that a set of things are "planets". Then we find a whole lot of new things that should be in that set, but then we'd have too many planets. So we choose a more restrictive set.
"Planet" is a category we made up. There's no hard line between "planet" and "not a planet". It's a cultural and historical thing. It's not a category that helps scientists. To scientists there are Planetary Mass Objects which are bodies large enough to have been pulled into a sphere by their own gravity, but not so large as to undergo fission. These don't even need to be orbiting a star, rogue planets.
Scientists tend to further split up "planets" into rocky planets (Mercury, Venus, Earth, Mars) and gas giants (Jupiter, Saturn, Uranus, Neptune).
Under Geocentrism
In antiquity "planets" were the "wandering stars" visible to the naked eye rotating around the Earth. Depending on who you asked, this was Mercury, Venus, Mars, Jupiter, Saturn, the Sun and the Moon. Ptolomy included the Sun. Yes, the Moon and the Sun were considered by many "planets" because in geocentrism these all orbited the Earth. And Earth wasn't a planet, because it was the thing everything else orbited.

The Two-Sphere model of the Latin Middle Ages
Under Heliocentrism
Then people noticed Jupiter and Saturn have their own things orbiting them. Things that didn't orbit the Earth! Some people called them planets, some called them satellites. Eventually we realized planets are things which orbit the Sun, and that eventually included the Earth. Now the planets were Mercury, Venus, Earth, Mars, Jupiter, and Saturn.
Comets and Asteroids and Moons, oh my!
The discovery of Ceres in 1801, and other asteroids, caused a new problem. To 19th century astronomers it looks like a planet: a thing orbiting the sun. Originally it, and other large asteroids, were considered planets. But by mid century it became clear these were much smaller, grouped together, and there were A LOT of them. So the category of "asteroid" was invented to separate them from the planets.
The discovery of Neptune in 1846, discovered by mathematical prediction, seemed to be the end of the planets. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune were the planets, there weren't any more.
Planet X
After the discovery of Neptune by observing perturbations in Uranus' orbit, people started predicting a tenth planet, Planet X. In 1930 an American found Pluto, just a tiny dot that moved between two images, but that was enough.

Initially people thought this was "Planet X" with a mass close to Earth's. Then in 1948 it was closer to Mars. In 1976 it was realized Pluto is far more reflective than assumed and had maybe 1% the mass of the Earth. We now know it has 0.2% of Earth's mass and considered a binary planet with Charon, they orbit a point outside both bodies.
But it was too late for a downgrade, Pluto was a planet. Until...
Plutinos, Trans-Neptunian Objects, Kuiper Belt Objects, and Dwarf Planets
In 1992 15760 Albion was discovered, a planet beyond Pluto. Like the discovery of Ceres two centuries before, this was taken to be a bit of an anomaly and largely ignored by the public. It hasn't even gotten a proper name.
Now the search was on and thousands more were found. But they were small and called "minor planets" or Trans-Neptunian and even further Kuiper Belt Objects. No threat to the established order.
Then in 2005 Eris is discovered, a Trans-Neptunian Object more massive than Pluto. Is this a planet? More quickly followed and Pluto was looking less like a planet and more like just the first TNO found.
Again the problem arose of what do we want a planet to be? If Pluto is a planet, then so are Eris and Ceres the other large TNOs and asteroids. Do we want eight planets or eighty planets? Or do we arbitrarily say Pluto is a planet and Eris and Ceres are not?
Exoplanets
In 1989 we discovered the first exoplanet, a planet around another star. As before, it started with one or two a year. In 1996 we discovered six. 13 in 1999. 30 in 2002... With the launch of Kepler dedicated to finding exoplanets in 2009 the discoveries poured in. We're now at 3730.
Now that we're finding "planets" around other solar systems, and in bulk, it became even more important to define what a "planet" is.
IAU Definition
The International Astronomical Union, who would rather have not gotten involved in what was a cultural question, not a scientific one, finally stepped in. They had the unenviable task of coming up with a retroactive scientific definition to justify a cultural and historical set of Planetary Mass Objects. In 2008 they formally defined a planet as having...

an orbit around the Sun,
sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
"cleared the neighborhood" around its orbit.

Nobody has been happy since.
"Clearing the neighborhood" being the most controversial and difficult to define, though there are proposed definitions. Anything satisfying 1 and 2, but not 3, is a "dwarf planet". Anything satisfying 2 and 3, but orbiting a different star, is an "exoplanet" (though that definition is not formal).
"Clearing the neighborhood" is what knocked the TNOs (including Pluto) and the large asteroids out. Other proposals that kept Pluto in were either arbitrary or would leave us with (then) dozens or (now) hundreds of planets. For example, a mass cut-off that included Pluto would be arbitrary and still leave us with dozens of planets. A cut-off at a certain distance from the Sun would be arbitrary and still leave us with dozens of large asteroids. Simply defining a list of planets was arbitrary. So "clearing the neighborhood" it is.

Knowing the history of how often what is a "planet" has changed, and that its of little scientific significance, I personally can't get too excited about what is and isn't a "planet". Whether we call Pluto a planet or a dwarf planet or a Trans-Neptunian Object or a Planetary Mass Object, watching the New Horizons mission reveal Pluto was just as awesome.
Planet Nine
And we still expect to find more planets! The outer solar system is poorly understood and everywhere we look we find more dwarf planets.
Examining the orbits of TNOs, scientists have noticed there's an unusual tendency for planets beyond Neptune's influence to be clustered on the same side of the Solar System. This could be the result of a large rocky planet with a highly elliptical 15,000 year orbit on the opposite side of the Solar System: Planet Nine.

Orbits of TNOs proposed to be influenced by a hypothetical Planet Nine. Planet Nine is in orange.
"Color" and "Appearance"
What color is the Earth? Is it a pale blue dot? Or is it a swirl of blue, green, brown, and white? What color is Pluto? Is it the black and brown from the Hubble Space Telescope? Or is it the pink and silver marble revealed by New Horizons?
Is it even visible light? What about ultraviolet and infra-red light far more useful to astronomy. Few astronomical observations are done in the visible light range, Hubble is one of the last great visible light observatories. It's often done in other frequencies which both reveal more useful data about the object, and which our atmosphere is opaque to. For example, Voyager 2's cameras were sensitive to UV and visible light, they used filters for wavelength ranges corresponding to "UV", "violet", "blue", "green", "orange", and for the specific wavelengths of methane.

When we knew a planet's "color" is up to you. It's a matter of how good the resolution of our images were at the time. Generally when a planet is first discovered it's nothing more than a point of light on a few black and white photographs, or a few pixels in a single wavelength captured by a CCD. More observations are made with higher resolutions and in more frequencies. Many images of planets you see are "false color" images, composites of many images taken in a single frequency.
Similarly "appearance" is a matter of resolution. For a long time Pluto was a few blurry pixels, and Charon was a small bulge that would periodically appear.
When?
Let's a say "appearance" means we're able to make out large surface features like craters. And "color" means we know something like its true visible light color.
In that case if we include Pluto then it's very clear we didn't know the color and appearance of all the "planets" until New Horizons began sending back images in 2015.
Pluto via Hubble in 2003.

Pluto via New Horizons in 2015.

If we go with eight planets, then we didn't know the color and appearance of all the planets until Voyager 2 visited Neptune in 1989 and sent back our first real clear images.

Rather than go through all the planets, and because this post has gotten rather long, I encourage you to look at our observations of each over time and decide for yourself.
Comment: Interesting read... One little anecdote from when my daughter came home from school and told me that Pluto was an _Elf_ planet. I was wondering what her teacher had been smoking when it occurred to me she'd watched _Lord of the Rings_ at the weekend and had got a little mixed up...
Comment: @jamesqf I don't know much about how the sausage was made, just the outcome. Pluto's status is a distraction from this question, so I covered both angles and the history of "planet". From your comments you're pretty passionate about it, but this isn't the place to have it out. Maybe work up a question about the IAU process?
Comment: @OscarBravo Pluto wasn't demoted, it left our Solar System and sailed to the West. :)
Comment: You should really add a bit about the the IAU and how their ridiculous definition of planet came about.  It was not science:  basically one person's vendetta against Clyde Tombaugh which persuaded a very small minority of the IAU to adopt a definition deliberately intended to exclude Pluto: https://laurele.livejournal.com/4755.html
Answer: This depends a lot on exactly what you mean by "color/appearance of all the planets".
If you consider just the classical planets (Mercury through Saturn) we knew their color in prehistoric times.  We got a vague idea of what they looked like up-close with the invention of the telescope in the early 1600s -- Galileo saw bands on Jupiter and the rings of Saturn -- and this improved more-or-less continuously as telescopes improved until the 1960s when planetary probes took over.
Starting with Mariner 4 in 1965 we began a series of interplanetary missions which -- eventually, in 2015 when New Horizons photographed half the surface of Pluto -- completed the reconnaissance of all of the planets, both classical and telescopic.
Comment: Of course since Pluto isn't a planet, 2015 is the wrong end date...
Comment: @MarkC.Wallace [that is far from settled](https://www.independent.co.uk/news/science/pluto-planet-class-nasa-new-horizons-space-a8340891.html)(FWIW, I have no further interest in the final result).
Comment: @Mark Olsen  Astrologers through the ages say Mercury is variable, brown, or multicolored; Venus  white, blue, or green; Mars red; Jupiter orange, blue, green, or blue-purple,  and Saturn grey, black, or black-brown.   http://cura.free.fr/22plcome.html   Mercury is actually grey; Venus pale yellow; Mars reddish brown; Jupiter banded orange and white; Saturn pale gold, Uranus & Neptune pale blue; Pluto light brown.  http://curious.astro.cornell.edu/about-us/58-our-solar-system/planets-and-dwarf-planets/planet-watching/249-what-color-is-each-planet-intermediate  So ancient people were wrong.
Comment: That's sacrilege!
Comment: @Mark C. Wallace: Wrong!  Pluto certainly is a planet, despite the machinations of one person (Marsden) holding a long-term grudge.  And of course the question really isn't answered, because there are arguably planets like Eris & Quaoar that we know little about, and probably others yet undiscovered.
Answer: Here is a discussion of the astrological symbolical colors of various planets.
http://cura.free.fr/22plcome.html1
Mercury: variable, brown, or multicolored.
Venus: white, blue, or green.
Mars: red.
Jupiter: orange, blue, green, or blue-purple.
Saturn: grey, black, or black-brown.
Uranus: various or blue. (discovered in 1781)
Neptune: mauve or purple. (discovered in 1846)
Pluto: black. (counted as a planet 1930-2006)
Here is a discussion of the real colors of various planets, which are often  confused by the use of false color images:
http://curious.astro.cornell.edu/about-us/58-our-solar-system/planets-and-dwarf-planets/planet-watching/249-what-color-is-each-planet-intermediate2
Mercury: grey.
Venus: pale yellow.
Earth: blue.
Mars: reddish brown.
Jupiter:  Banded in orange and white.
Saturn: pale gold.
Uranus: pale blue.
Neptune: pale blue.
Pluto: light brown.
So naked eye observations since ancient times clearly established that Mars is reddish, and no astrologers assigned any other color to Mars.
And it is possible that ancient Babylonian astronomers and astrologers assigned the color orange to Jupiter because they could see that Jupiter looked orange-white to them.
But the other planets just appeared as whitish dots, and apparently astrologers felt free to assign whatever symbolic colors to them that fit with their theoretical framework about the pagan gods and mystical influences assigned to those planets.
Therefore, nobody seems to have known the colors of any planets except for Mars (and possibly Jupiter) until the beginning of telescopic observations in 1609.   And nobody knew any other details about the appearances of the planets until the era of telescopic observations beginning in 1609  - and until the era of space probes beginning in the 1960s for some of the planets.


Why did Gollum ever take off the ring in the first place?

Question: Bilbo was able to take the ring because Gollum had taken it off.
If you had the ring, and were accustomed to wearing it, why would you ever take it off anyway?
Comment: lol, i read that as "choking an orc in the IRC"
Comment: His day job was paddling in a boat and catching fish with his hands. Wearing a ring while doing that is asking to lose it. Especially one that likes to to slip off.
Comment: The ring fell off his finger while he was choking an orc IIRC.
Answer: I just read that passage last night; re-reading the story with my son.

Gollum used to wear it at first, till it tired him; and then he kept it in a pouch next his skin, till it galled him; and now usually he hid it in a hole in the rock on his island, and was always going back to look at it. And still sometimes he put it on, when he could not bear to be parted from it any longer, or when he was very, very, hungry, and tired of fish. Then he would creep along dark passages looking for stray goblins. He might even venture into places where the torches were lit and made his eyes blink and smart; for he would be safe. Oh yes, quite safe. No one would see him, no one would notice him, till he had his fingers on their throat. Only a few hours ago he had worn it, and caught a small goblin-imp.

Emphasis added on the last line - he didn't often wear it anymore, but had just gone out with it to hunt, which is the reason the ring could be found laying in the tunnel when Bilbo came along.
Comment: I wonder how many upvotes are for "re-reading the story with my son." (Here's another one. +1)
Comment: @ChrisLutz I suspect that's the case. Thanks. For the record - he rather enjoyed it, and we've moved on to Redwall now.
Comment: Ohh!  Thank you for reminding me about Redwall!  I can't believe I almost forgot it!!!  My seven year old and I are on the same journey now.
Comment: This is the correct answer, after a long time its seems that the ring becomes kind of toxic to the possessor even though they still want to 'own' it.  So it forces them to risk it by moving it further and further away.
Answer: The ring was capable of taking indirect action on its own.

The Ring also caused those who possessed it to become obsessed with it, so much so that they might kill anyone who showed too much interest in it or attempted to touch the Ring. With an evil will of its own, the Ring would make attempts to return to its Master. It could "call out" subliminally to other persons, in an attempt to get them to pick it up or possibly kill the current owner. It was also capable of slipping unnoticed from the owner's finger, leaving him vulnerable to attack or to gain a new owner that would help get the Ring back to Sauron. Frodo Baggins was warned by Bilbo that the Ring tended to "slip away" at odd times, and compensated for this by wearing it on a chain around his neck.

As such, it is likely that the Ring left Gollum, sensing Sauron's return to power. As the caves were filled with goblins, trolls, and orcs, it likely expected to be picked up by one of them at which time it could begin moving back to its Master.
Comment: ^into his knee.
Comment: `He leaped into the waters, but the Ring slipped from his finger as he swam, and then the Orcs saw him and killed him with arrows`
Comment: @Jared You could say he used to be King of Gondor but then he...
Comment: @jacen.garriss Gollum did not need to be aware of the Ring's influence in order for it to exist.
Comment: @jacen.garriss Again, Gollum did not need knowledge of the Ring's influence over him for that influence to exist. If you want Gollum's internalized reasoning for removing it, then read the answer by Saiboogu.
Comment: But Gollum did not know of these things so why would he himself take it off? He had no reason to.
Comment: Yes, but why would he specifically take it off if he did not know there was an influence besides the fact that he loved and hated it.
Answer: From this answer:

if [a mortal] often uses the Ring to make himself invisible, he fades:
  he becomes in the end invisible permanently, and walks in the twilight
  under the eye of the dark power that rules the Rings.

So wearing the ring can wear you out.
Answer: It is simply stated in various JRR Tolkien books that the ring has a will of its own and manipulates and betrays the ring bearer when it's most convenient for the ring, effectively choosing a new bearer from time to time.
Answer: Something Peter Jackson brought to the films, which I'm not sure was very prevalent in the books, is that the Ringworld, what you see while you're invisible, is not a very pleasant view of the world, and not a place you want to be for long periods. The effects used in the film to show the Ringworld were meant to be an answer to this obvious "audience question".
Also, while the Ring is being worn, and the bearer is using its power, the Nazgûl and other servants of Sauron can sense its presence more keenly. If it's in your interest to keep the Ring secret, then you don't want to be wearing it for long periods or you'll lead the baddies right to you.
Answer: Gandalf answers this clearly and explicitly:

'There was more than one power at work, Frodo. The Ring was trying to get back to its master. It had slipped from Isildur's hand and betrayed him; then when a chance came it caught poor Déagol, and he was murdered; and after that Gollum, and it had devoured him. It could make no further use of him: he was too small and mean; and as long as it stayed with him he would never leave his deep pool again. So now, when its master was awake once more and sending out his dark thought from Mirkwood, it abandoned Gollum. Only to be picked up by the most unlikely person imaginable: Bilbo from the Shire!
'Behind that there was something else at work, beyond any design of the Ring-maker. I can put it no plainer than by saying that Bilbo was meant to find the Ring, and not by its maker. In which case you also were meant to have it. And that maybe an encouraging thought.'

Note that Gandalf sees two entities at work here: the Ring, desiring to get back to its Master, and "something else" "beyond any design of the Ring-maker" Who meant Bilbo to get the Ring.
Gollum didn't leave the Ring, the Ring left Gollum.
But the Ring's evil purposes in finding a new owner were taken by Ilúvatar and turned to its despite:

Then Ilúvatar spoke, and he said '...For he that attempteth this [Evil] shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined.'
Answer: I am assuming that this was a joke/comic insight...and it was pretty funny :)
Maybe, since he couldn't die while he had the ring...and since he couldn't live without having a little "good" left in him (his soul--a sort of Socratic view of the soul), the natural effect was a bifurcation of his personality...the good side that wept and cried in the darkness, Sméagol...and the dark, obsessive side enraptured with the ring, Gollum.
In order to survive, he relied on Gollum...in order to live, he separated from the ring so that Sméagol could exist.  Anyways, that's my theory.  Makes sense when you think about why a starving, corrupt creature would agree to play a game of riddles with a plump, helpless hobbit.  Or later save Frodo's life while, at the same time, planning his death (the climb to the spider's lair, I think...I'll have to double check).
So...now that I put some of the basics down...
Gollum might be a duality: Sméagol and Gollum.  According to Socrates (my philosophy 101 class) you must have a soul to be alive.
The ring possesses Sauron's soul, which, apparently, is immortal.  It follows that Sauron's soul possesses the ability to grant those souls around it temporary immortality as well.  However, one does not need to actually wear the ring to be immortal.
Next, when one puts on the ring, one becomes invisible: truly invisible.  Recall that Gandalf mentions that true invisibility is basically non-existent in his thousands of years of experience on the earth (first book of LotR, I believe).
Now consider this: why does the ring extend the immortality of Sauron's soul to the bearer, but fail to actually turn the bearer himself Into Sauron? i.e. a Sauron ghola.
Perhaps this is where the soul comes into play:  Since one must have, according to Socrates, a soul to exist...and since all souls are created equal (like charge-positive, negative), then when one piles Sauron's inanimate soul (bound to a ring) on top of an animated soul (a living body), the two neutralize each other, which manifests in the form of "true" invisibility.
So...since Sméagol exists for 600+ years bearing the ring without turning into Sauron, I think that his continued existence (and, therefore Sauron's) is dependent on him not always wearing the ring...so the ring must slip off of his hand in order to protect itself, lest they both disappear into the wraith-world, and Sauron's tie to the Mortal plane disappear forever.
Anyways, I am pretty sure that is the gist of it: either it is Sméagol reacting to preserve himself and survive, or it is Sauron's soul leeching as much life from it's host without killing them both...Either way, I bet that, in Tolkien's microcosm, neither the ring nor the bearer can survive if they are joined forever.  Or maybe its just a hassle to walk up stairs when you can't see your feet.  I don't know.
Comment: "According to Socrates (my philosophy 101 class) you must have a soul to be alive." According to J.K. Rowling, you don't.
Comment: Lol.  I'm not citing it as a "fact"... I think that you have to consider who Tolkien's contemporaries were: C.S. Lewis etc.

In the early 20th century, there was a movement back towards fundamental western beliefs...and literary guys like C.S. Lewis and J.R.R. Tolkien were at the center of that reactionism.  Check out the screwtape letters and tell me that Socrates, Westernism, and the New Testament isn't all over that.  Then, consider that C.S. Lewis and J.R.R. Tolkien were both hugely popular literary contemporaries.
Comment: Anyways, in the case of J.K. Rowling, you do need a soul to survive.  That was the whole point of the Horcruxes: as long as a piece of Voldemort's soul remained, he could continue to exist.

Comon man, get your geek on.
Comment: Yes, I know. Just a little comparison. We all know JKR only sticks to the theories she likes.
Comment: lol, too true: infinite energy, mutable information, morals existing in costless societies.

Anyways, if I were a wizard, my best spell would be: "Mea Culpum"
Answer: Well,Goullum didn't really take the ring off.He had it in his pocket while he was fighting a goblin and Bilbo was hiding. Then the ring fell out of Goullum's pocket and
Bilbo found it.
Comment: If it was in his pocket, he had to have taken it off.
Comment: He'd also need pockets!


Are there consumer/prosumer-level digital-to-film or digital-to-photo-paper projectors/enlargers?

Question: My source image is a medium-high resolution (say 50MP) digital capture and I'm interested in producing a darkroom print from it, there are industrial machines like the Durst Lambda and other minilabs that can do that but they're not affordable to an individual practitioner, is there something that is ? Mind you I don't need the printing part - just the projection.
Comment: How large do you want to print? Is there any reason you do not want to use a print service?
Comment: [Hueco has described](https://photo.stackexchange.com/a/101168/75526) about making contact prints via transparencies.
Comment: A standard 8x10 would be a good start, and because I like the idea of end-to-end authorship I guess.
The idea of an inkjet transparency contact print is interesting though transparencies traditionally have a lower dynamic range then either modern digital or photopaper.
Comment: So apparently this is the somewhat standard practice and has a  name - https://en.wikipedia.org/wiki/Digital_negative_(transparency)
Answer: That is not very affordable...
You would need to have a projector of more than 8K resolution, and that only gives you 7680×4320px, or like 33Mpx.
A normal projector is only FullHD, this is 1920x1080.
You could take an 8K monitor and take a photo, for example using black and white film.
There were digital to film printers, but they were extremely expensive. They were used for example to pass visual effects to film for distribution.
https://en.wikipedia.org/wiki/Film-out
Answer: This isn't exactly what you're looking for...
But Fuji makes a printer that uses their instax film. It receives the image over wifi, exposes via LED, and then pops out the print.
Per the comments, digital to transparency can work to get a darkroom print from digital. You're right in that some range is lost.
Frank points out in a comment that you could also simply print the image and contact print this - just keep in mind that your exposure doing this will get rather lengthy.
Answer: There have been a few attempts to bring something like this to market. I'm not aware of anything that has gone much past the fundraising/initial run stage.
The ones I've seen though have worked with smart phones as both the "negative carrier" and the light source. For example the "Enfojer" -- https://www.indiegogo.com/projects/enfojer-old-school-darkroom-for-smartphones#/ and the Fojo -- https://www.facebook.com/fojography/


Recommended programming language for remote sensing?

Question: I am beginning studies that hopefully will lead to a long career as a remote sensing specialist.  I am currently working with ArcGIS for some applications and learning ENVI for others.  I have realized that it is imperative that I learn a programming language, and am stuck facing a choice between IDL and Python.  I would love to hear which programming language the community recommends for the remote sensing of land surface processes.
Answer: IDL is a fantastic stand-alone programming language (you do not need ENVI). I particularity like it for very fast matrix processing on large arrays. @Aaron makes IDL sound much less flexible then it really is. The majority of IDL development came out of the Physics and Astronomy communities. There is robust support for mathematical and statistical programming. If bundled with ENVI, you have all the library calls (functions) available in ENVI including support for spatial vector objects. There are also a large number of functions and models developed by the user community. One advantage to learning IDL is that it will make you marketable in "analytic" remote sensing shops.
Also, do not forget that ERDAS has a scripting language (EML) that is quite good and easy to learn. EML is the backbone of the graphic modeler and gmd's are just packaged EML scripts that sit under the graphic modeler interface. The advantage of using EML directly is that you can use for/while loops and have access to more ERDAS functionality in a scripting language.
MATLAB is also very good for matrix processing and there are open source versions (e.g., Octave) that have exactly the same syntax with similar benchmarks. This is a highly flexible language with considerable power. It is one of the preferred language for applied mathematics and engineering.
The Python alternatives NumPy and SciPy are flexible but not as optimized as IDL and MATLAB. As such, you need to deal with addressing space and speed when working with large arrays. One huge advantage of Python are the additional libraries for performing a variety of analytical tasks. There are packages for remote sensing,  nonparametric statistics, bindings to spatial classes (e.g. GDAL, LibLAS) to name just some of the added functionality available through packages.
This brings us to R. I am primarily a spatial statistician so, this is my everyday language. The number of available packages is staggering which, in turn, provides access to cutting edge cross-discipline statistical methodologies. However, I have to say that it is very cumbersome when dealing with large data problems. The spatial classes are getting much better and because of the raster package providing the ability to hold large data out of memory I am now able to implement some fairly complex statistical models utilizing large raster arrays. But still, R is slow when dealing with large memory problems. The BigMatrix package allows for writing and processing huge arrays from disk but the coding overhead is not insignificant There are also bindings to GDAL and GIS software (e.g., GRASS, SAGA) that allow spatial object processing to occur outside of R in a GIS specific software, which is how I interact with GIS software these days. This allows me to leverage functionality across multiple software without leaving R.
So, now that the software cheerleading is out of the way, my recommendation is "yes to all of the above options". Programming is a skill that, once learned, is easily applied to other languages. There are striking similarities between C++, R, IDL and Python. Aside from some coding idiocentricities, what one must learn are the available functions to implement a given model/task. Once this is done it is just a matter of syntax that implements common coding structures.
Sometimes there are things that just work better in a different software or language. I occasionally write code in FORTRAN or C++ because it is just the best choice for a given task. It is a matter of adaptability. You may want to start with Python because, as a  scripting language, it can be applied to numerous tasks it also provides availability of packages for specialized analysis, has a number of free online resources and is somewhat easy to learn.
Comment: I upvoted this not only because it's well written and responsive but also because I have had similar experiences (including the occasional foray back into Fortran :-) and draw similar conclusions about these languages and application environments.
Comment: +1 A good summary of the available tools out there.  Thanks for mentioning EML.  From a scripting perspective, EML is a bit clunky compared to Python (IMOP), although very handy if Erdas is your RS GUI of choice.  Unfortunately, there is not a unified language that brings the best from GIS and RS.  I absolutely agree that each person need to use the best available method and have a variety of languages at their disposal.  A one-language RS specialist is rare in the field, I believe.
Comment: I agree that starting with Python sounds like my best bet, given the fact that it is open source and that there are many online resources available.  I do have access to ENVI, but for my current research, I can manage without knowing IDL.  I am also studying spatial statistics, so R will also be important.  @Aaron seems to be right - RS specialists must be multilingual!  Thanks again for the detailed response.  This is really a huge help for someone just starting out in the field.
Comment: @Emily, for spatial statistics in Python take a look at the PySAL package (https://geodacenter.asu.edu/pysal). There is a book by Kenneth Bowman, "An Introduction to Programming with IDL" that is a quite good general introduction. I think that you would be surprised how far you would get by just working through this one book. As I mentioned, much of the syntax and coding structure are similar between the languages mentioned so, no wasted time. Since you are working with ENVI some basic knowledge of IDL would be helpful in your research. It is not all or nothing with a given language.
Comment: this post is a good summary -- an addition from my experience: Considering the high price of ArcGis, Envi, Matlab and other tools, I prefer OpenSource, which is free.

For me a combination of Python / gdal and QuantumGIS works perfectly. Others at my workplace use Matlab (but also very expensive).

In my surroundings, R seems to be mostly used by biologists for some reason.
Answer: From a remote sensing perspective, the main benefit of IDL is that it extends the capability of ENVI similar to how the Python arcpy site-package extends the functionality of ArcGIS. If you will not have access to the ENVI platform, consider learning a different programming language. Additionally IDL is a commercial product whereas Python is open-source and has a huge support base.
From a practical perspective, Python, R (open-source) and MATLAB (commercial) are the most important languages for my day-to-day remote sensing based work.  I use MATLAB for much of the digital image processing, Python for more GIS related tasks and R for graphics/analytical purposes.
Finally, if I had to focus all of my efforts on one language, I would choose to learn Python mainly because Python functionality is much more suited to GIS-related processing in addition to RS based functionality.  In other words, Python is a jack-of-all-trades whereas IDL is not.  Besides, NASA uses Python!
Comment: There are many modules within python, like pyh5 and numpy/scipy. There are also larger libraries like [OSSIM](http://trac.osgeo.org/ossim/), specifically for image processing.
Comment: +1 on python.  It's a general purpose language, and if you need to use tools that may fall 'out of the box' withing GIS scripting, python can do it.
Comment: Don't forget about Rasterio: https://github.com/mapbox/rasterio a new library for rasters for Python.
Comment: Thanks guys, sounds like I'll start working on Python and expand to other languages once I have that one down.  Many thanks for your help.
Answer: I strongly suggest learning basic computer science theory instead of focusing on one procedural language. Acquiring a foundation in CS theory would allow you to use programming languages interchangeably. On a day-to-day basis I use two to three languages to write code (Mostly Matlab, R, Python), and in the last month I've also written code in VB, BATCH, and EASE (PCI Focus).
This is not only important to be able to easily learn multiple languages, but to avoid making basic mistakes.
A few recommended topics are:

data types, memory usage
conditions
iteration
pattern matching
procedural paradigm, modularity

Also, if you're having issues writing code take a step back and write pseudocode. Basically write step-by-step the logic behind your code and what you want it to accomplish.
If you're a student I recommend taking first and second years comp sci courses.
Cheers.
Answer: I think this is worth a separate answer: An absolutely great page for learning on how to use Python for Remote Sensing is this one, lecture notes being a great tutorial: http://www.gis.usu.edu/~chrisg/python/2009/
For me, a combination of Python and QuantumGIS solves all my Remote Sensing and GIS needs.
Answer: it really depends on packages you hope to use in remote sensing (image analysis).  ArcGIS (ESRI) is not a remote sensing package.  If you want to use open source packages I would agree that Python and R are great languages.  I would also consider C++ and C, so you can dive deeper into some of the libraries (ie: GDAL).  If you want to stick with commercial off the shelf (COTS) packages, then you will want to look more into the C languages (C, C++, and C#).  Happy coding.


Canny Edge Detection and LoG difference

Question: What is the difference between Canny Edge Detector and LoG(Laplace of Gaussian) in Diagital Image Processing ?? I am totally new to Digital Image Processing .. I would be thankful if someone could tell me the difference . Thanks and Regards.
Answer: The Canny edge detector is based on the first derivative of the image (Sobel mask convolution in x and y direction). The magnitude of the derivative will look like this:

You see that with this operation lines can be identified by pixels which have a high value (are white). The canny algorithm will then also apply non-maxima suppresion and line tracing (see Wikipedia).
The Laplacian of Gaussian operator however, is based on the second derivative of the image. A response of this operator will look like this:

The highest response of the LoG operator will be at the center of blob-like structures in images (same size as the LoG kernel). Lines can be identified using the LoG operator not by finding high magnitudes in the image but by inflection points (zero-crossings). You can see that each line is on one side dark and on the other white. Based on the second derivative, it is highly sensitive to noise.
Comment: What is first derivative and second derivative of an image?
Answer: Both are algorithms to detect salient features in images. The Canny Edge Detection looks for edges in the input image. The LoG however looks for blobs in the image, it does this by considering the same image on multiple scales (by scaling down the image repeatedly). However, both are algorithms frequently used to detect salient points in images.
For the differences in the actual algorithms you should consult a textbook or Wikipedia.
Computer vision often needs a set of salient points in an image, for example to compare images, detect objects and so on. However, there is no method for salient point detection which will be best in all cases. Both Canny and LoG are approaches to detecting salient points, but which one works better depends upon the situation.

Canny Edge Detection and LoG difference


Should a very old question asking for software recomendations be flagged?

Question: The question mentioned is five years old, has no votes, and has three answers. Does its age preclude it from being flagged as a software-rec, or should it still be flagged?
Comment: If it is not on topic then the question should be closed.
Comment: Related: http://meta.superuser.com/questions/3783/what-can-i-do-with-old-questions-that-i-think-should-be-closed
Answer: Flag it. It should probably be removed.
Answer: Short answer: see Oliver Salzburg's.
Longer answer: There are 10s of thousands of old questions that are now off-topic.  They might be viewed as bad examples, and some of them as "diluting" the quality of the site.  However, they aren't really doing any harm if they're just buried.
So it doesn't make sense to search them out and close them all.  It would create a massive review job.  It's difficult to keep up with just the new questions, and the effect would be like spitting in the ocean.  However, it's different when they attract new poor answers and steal exposure from new questions.
When you come across one, first assess its potential.  Many questions request a software recommendation because the OP isn't aware that the problem can be solved without it.  Decide whether the question could have value if you edit it to simply request a solution to the problem.  (If it's old, with no votes or favorites, low views, and the answers are just low-effort, low-quality software recs, that's an indication of its value.)
If the question has no real value to anyone else, or can't be edited to make it on-topic, flag it. That's especially true if it is attracting bad answers (e.g., the reason you found it was because someone bumped it into the active questions by posting a new, link-only software rec).
Comment: The situation in your last sentence happens *a lot*. That's why I close old recommendation questions when dubious answers appear in Late Answers. I've added an answer to this effect.
Answer: Many people here use downvotes to show something is wrong, this includes alerting the poster that the question is off topic.
Flag it but, IMO, it shouldn't be downvoted. If anything, I'd love to see as soon as a vote is cast, the voting is locked to prevent this, although I am aware that this wouldn't work for many other reasons.
Answer: Yes please. I frequently see low-quality software recommendations (borderline spam) in the Late Answers queue from low-rep or new users. Such posts don't really serve a purpose, and when I come upon them, I vote to close the question, no matter how old it is.
If we close these questions before the dubious posts come flooding into the answer section, we save reviewers time and make Super User look better - devoid of sketchy links.
Comment: Now that you mention it, it isn't unusual to see a very old software rec question  that somebody has rediscovered and "updated" by posting a new software link.  That bumps it to the active questions and starts a new feeding frenzy of everyone chiming in with their current favorite.
Answer: This is my thought - If it was voted for and replied to with "relevant" answers there's some good to it.
But, given that now there is "Software Recommendations" Site on stack exchange in addition to Super User it should ideally be moved there.
Funny thing is, I had no idea Software Recommendations had come up as I primarily remember good ole holy trinity :)
I had a similar quandry when I posted this few years back in Productivity as Software Rec did not exist and Super User was not a good fit as it was related to better life & schedule management.
https://productivity.stackexchange.com/questions/8630/manage-personal-vs-non-personal-activities-calendar-event-times-across-differe
PS: I'd be curious to know what would be the ideal place to post it now?
I still do not have a conclusive answer.
There are times when a post may be equally apt for 2 SE sites. Better to find a better fit & move the thread to a better location, than to delete & trash the collective efforts of people.


Generate java classes with wsdl/xsd files using RAD

Question: I am new to webservice world. I just got WSDL and XSD files from another Interface Application and want to start from here. Can anyone please help with the steps or tutorial to generate java classes with available wsdl and xsd files using RAD?
Answer: Two walkthrus for this process
IBM's docs
OR you can try this Websphere docs
Answer: There are a number of resources. YOu got to state the version of RAD that you are using. Redbooks are a good source for such information besides the Infocenter.
This approach that you are looking at is called a Top-Down Process where in you start with the WSDLs & XSDs and create the service implementation.
Try this one: http://www.redbooks.ibm.com/abstracts/sg247672.html
Look at chapter 18 Developing Web services applications and you should be looking at "Creating a top-down Web service from a WSDL"
HTH


How much can I post about my script on meta if it's relevant?

Question: I've made a userscript for enabling moderation features and I've found many MSO posts where it would be relevant to post an answer or a comment.  So far, I've only posted one answer and one comment.  I would like to post more about this on several posts where it is completely relevant, but I'm afraid that it would be considered spam.  Is it okay to post a large number of relevant comments and answers on meta sites?
Comment: I'm afraid I'd be repeating myself, but you're basically insisting that all the negative feedback you've been getting is in no way your own fault. Do you imagine that there's some conspiracy against you, or your content? There isn't, I can assure you of that. You might want to incorporate the feedback that you get, instead of just insisting that you're right, and pretty much everyone else isn't. You'll have a better experience going forward if you try to do that.
Comment: This question is basically asking, "I did something I think is cool, is it ok if I mention it in a bunch of places?" While this might be a reasonable question, it's also possible that some users see this as needless self-promotion, which is not viewed favorably. It's also possible that users are unhappy with your frequent complaints about downvotes. Getting unexplained downvotes is just one of the realities of posting content, and I'd suggest you just get used to it.
Comment: I'm not referring to this post specifically, but several of the other posts you've made that you claim have been unfairly negatively received. If you sincerely think you've not received any feedback on how you can improve the questions you post, then I guess we'll just have to agree to disagree on that.
Comment: As to your StackApps post being downvoted, well, you literally just asked (indirectly) a wider audience to review it. Complaining about getting negative feedback after that is not really in good taste.
Comment: I've migrated it here because the only community that can decide whether certain types of posts are welcome on MSO is MSO itself...
Comment: Relevant: https://stackapps.com/questions/6192/how-can-i-introduce-my-stack-overflow-app-to-other-users
Comment: @cigien How can I incorporate feedback if there's no explanation?
Comment: @Anonymous Well, the answer part is unlikely to become welcome here, since that would mean all the answered questions should rather be closed as duplicates, if that answer is really appropriate.
Comment: Given that your scripts are aimed at Teams, MSO is the right place. Otherwise, I'd pick [meta.se].
Comment: @cigien "Getting unexplained downvotes is just one of the realities of posting content, and I'd suggest you just get used to it." - it's happening on every post, every time, and in a large number...  "As to your StackApps post being downvoted, well, you literally just asked (indirectly) a wider audience to review it." - I don't see what could be wrong with the script.  "While this might be a reasonable question, it's also possible that some users see this as needless self-promotion, which is not viewed favorably." A) It isn't needless B) I tried to post this on Stack Apps but it got migrated.
Comment: @Glorfindel I was intending to ask about the Stack Exchange community at large (just using MSO as an example, but I suppose it's more relevant here...
Comment: @πάνταῥεῖ What if the answer is different but both would be useful to have a link?
Comment: Evidently the community here doesn't think it's relevant, or else it wouldn't have 3 downvotes so shortly after posting.
Comment: And now people are downvoting my Stack Apps post (for no reason).  This is why I didn't post it on MSO.
Answer: The self-promotion guidelines are essentially the same on Meta as they are on the main site. They're all covered in this Help Center article. I'd quote the relevant bits here, but they're really all relevant, so you'd do well to read and follow them.
A common misunderstanding is that these rules were developed only to prevent people from profiting financially from contributions. That is to say, that they would not apply to the promotion of open-source projects or other efforts that are strictly meant for "public good". That is not the case. Several years ago, Brad Larson wrote a really great answer on Meta that we moderators still link to regularly when confronted with the objection "…but, this is an open-source project!". Userscripts are almost necessarily open-source and generally always developed for the general good of the community, but that doesn't make them an exception to our promotion rules.
Posting an answer that solves a problem is fundamentally useful, whether it's on the main site or on the Meta site. So, if someone is experiencing frustration with one of the site's features or anti-features, and you have a userscript that solves that problem, then posting an answer that provides a link to the userscript, an explanation of how to use it, a demonstration of how it solves the problem, and a disclaimer of your affiliation is a useful contribution.
Note that just because a contribution is useful in the abstract doesn't mean that everyone will like it or be supportive of it. Therefore, you may receive downvotes on such answers. There are zillions of possible reasons why someone may choose to downvote an answer like this. Maybe they're reacting negatively to what they perceive as self-promotion. The tone, style, and frequency of the answers has a lot to do with this, and it can often be controlled, but not always. Some people are impossible to please. Or, maybe they think your script doesn't really solve the problem, so it's essentially irrelevant. Or, maybe they tried to use your script, but it didn't work for them. Or, maybe they think it's a bad idea to write scripts that work around site bugs, because that could discourage the developers from taking the time to fix them. Who knows. Take the feedback for what it is: someone on the Internet disagrees that this is a useful/correct/relevant/helpful post.
For what it's worth, you're in good company posting userscripts in answers to Meta questions. We have lots of community members who do it (CertainPerformance is merely one who comes to my mind immediately), and many of these posts receive upvotes. In fact, it just so happens that one diamond moderator is a prolific author of userscripts and often "plugs" his own scripts. He's not immune from downvotes, but these are generally well-received. (In large part because the scripts are just so darn useful and well-written.)
I would encourage you to post answers, rather than comments. I would also encourage you to avoid "a large number of" anything, at least at first. Build up some goodwill, put in some time with the community, and see how it goes. Ramp up your participation and promotion over time, as you see positive feedback from the community.

As far as specific feedback, the answer you started with is…not great. It is in need of improvement on several fronts. First, it starts with the word "this". What is "this"? The question is a how-to question, asking how to get access to tools, and you say "this is useful"? What's useful? Are you trying to tell the person that the thing they are asking how to do is useful? Yeah, I expect they know that. As such, the bulk of your answer doesn't seem to be adding anything to the post. The real substance of the answer is just this line:

These features are still there - just hidden by the UI. I've created a userscript to show them.

Unfortunately, that's buried at the bottom. More unfortunately, there's nothing in the body of the answer itself that shows to use your userscript, shows how it works, or describes which specific features that it unlocks. A good "how to" answer is a good "how to" answer, whether it's describing how to install and use a userscript, or how to install and use a Visual Studio extension.
Comment: "More unfortunately, there's nothing in the body of the answer itself that shows to use your userscript" - if they're interested, they can easily enough read on Stack Apps how to use it, and I don't want the answer to look too much like an advertisement and more like an actual answer.


How transactions are broadcasted to Block Producers?

Question: When a transaction is initiated and send by a user, how are these transactions broadcasted to Block Producers?
Answer: Each Node in the Network adds a list of peers it communicates with to exchange data.
When a transaction is sent to a node, it is passed on to the peers and this way broadcasted to the entire network of producers.


Should I chose a vertical or a horizontal HF antenna?

Question: If I only have the budget for one HF antenna, should I chose a vertical or a horizontal antenna?
Comment: If budget is your primary concern, all you need is some coax and some wire and you can throw up a dipole in minutes.  On HF, Horizontal is preferable anyway.  On the lower frequencies (75) your primary work wiill be with ground waves.  On higher (40/20) it can also be by skywave which tends to rotate unpredictably as it interacts with the ionosphere.  Since most people tend to use Horizontal means that your signal-to-noise ratio will be worse if you are using a vertical.  i.e. you will hear more QRN (Natural noise).  Wire antennas are always least expensive, and there are a ton of varieties.
Comment: I see this was posted 3 years, 8 months ago  Funny it would pop up now.  But it is a great question all the time.    So hello from the Future, Timtech.  (July 2017)
Comment: Thanks @SDsolar, thankfully my diagonal antenna allowed me to time travel, so I'll be heading back to 2013 and tilting it until it's horizontal.
Answer: Summary
If you can have only one antenna and can chose between a vertical HF antenna or a relatively high horizontal HF antenna, go for the horizontal antenna.
Modelling results
In January 2008, L. B. Cebik, W4RNL (SK) published what was going to be the last entry of his seminal 10-10 News series. It turned out to be an interesting gain comparison of single element 28.4MHz antennas modelled over various ground types of which a summary is presented here (Table 1). His findings seem to fit well with what John Devoldere, ON4UN modelled and published for equivalent antennas on the lower HF bands.

Horizontal HF antennas: near-by ground gain
At a height of about λ/2, the nearby ground reflection of a horizontal HF antenna will start to be constructive at interesting take-off angles for long- distance ionospheric contacts. This will provide a net gain over the antenna in free-space.
Vertical HF antennas: near-by ground loss
This is not the case with vertical HF antennas. Nearby ground only contributes loss. This even more so when the ground forms part of the return path of the radiating structure. Even when far-away ground reflections may cause the directivity of a vertical HF antenna at low take-off angles to be much higher than that of a horizontal HF antenna, its net gain will still be lower at those angles. This makes the horizontal HF antenna a clear winner, at least for what transmission is concerned. Note that gain and directivity are not synonyms; gain takes into account losses, directivity does not.
Vertical HF antennas still remain useful
Vertical HF antennas do have their merit though. At the lower end of the HF spectrum, the λ/2 height requirement for horizontal antennas can become cumbersome (even though a horizontal phased array may weaken this requirement by allowing somewhat lower heights). A vertical HF antenna can get away with a height of only λ/4. Furthermore, the directivity of a vertical HF antenna can be effectively employed at the reception end to cancel out high-angle interference by near-by stations. This is why some stations use receive-only phased-arrays of verticals on the low bands.
Polarisation at HF
Polarisation is not really an issue at HF (apart from lightning and man-made noise considerations). This is so because the ionosphere is mainly an anisotropic medium, i.e. it messes up polarisation.
Comment: This is a gross oversimplification. There are advantages to each -- but there's certainly no "clear winner".
Comment: @on4aa that's a [cherry-picked result](https://yourlogicalfallacyis.com/the-texas-sharpshooter) which uses *phased arrays*. It's likely that someone with only one antenna does not have an extensive array, and quite possibly whatever made one antenna better in that very specific test does not apply in the general case of a simple vertical/horizontal choice.
Comment: [Here](http://w4rnl.net46.net/ant26.html) is what the late L. B. Cebik had to say about this: *"...there are some good reasons for using a vertically polarized antenna on 10. Although the gain of such antennas may not usually compete with a well-installed horizontal antenna of the same size..."* Read more [here](http://w4rnl.net46.net/ant26.html).
Comment: @on4aa I don't see anything in that article to substantiate that claim.
Comment: Bob Raynor, N4JTE, backyard testing: [phased horizontal wires outperformed phased verticals on 80 & 40m in almost 100% of the single-blinded tests](http://www.eham.net/articles/31037).
Answer: It doesn't really matter.
You're asking about a topic called polarization, which is really important in VHF and UHF. It's the reason why rotating your HT can improve or harm your reception, and it's also the reason why some 3D glasses and sunglasses work. But because of the way HF propagation works, it doesn't really matter. Any ionospheric propagation gets the polarization randomized anyway. Very short range (ground wave) HF works best with a vertical antenna, but it's very rare that you care more about short-range than long-range.
In terms of limited space and cost, it's probably easier to set up a horizontal antenna (or an inverted V like a G5RV or OCF) than a vertical simply because it's easier to string a wire through some trees than it is to secure a flagpole or tower against gravity and wind loads.
Comment: @MichaelKjörling that's a pretty broad statement. Ground wave on 80m can go pretty far.
Comment: Oh okay, I'm not really familiar with polarization.
Comment: It's easier to get NVIS HF with a horizontal than vertical antenna, and NVIS on HF is a lot more useful than ground wave on HF.
Comment: @PhilFrost-W8II It sure can! Even during the day. I spend a lot of time in QSOs -even during the day- with hams from my QTH in SW Missouri. You should join us! :-)  Contact me for the frequencies, we'd love to have you!
Comment: That is very true, @Phil.  Especially at night.  I grew up in Alaska talking with people all over the state using ham radio as their primary source of communications.  Most of what I did over the years was Morse - I have log books full of contacts on 80 Meters.  All on an inverted-V antenna strung from a 50 foot wooden tower.  Alaska is a very large place, physically.  About a third of the size of the whole US if you lay it over it.  80 Meter CW was pretty reliable.  Sniper Net used SSB at 3905 had 20-30 regulars.
Comment: On a similar subject, I worked as Chief at KFAR in Anchorage, 590 AM.  We would receive tapes and letters from people all over the top of the world over the pole who could hear us at night.  That was on a quarter-wave vertical with 120 ground wires (every 3 degrees) and good soil, and plenty of power.  The Big Daddy is KJNP (King Jesus North Pole) - "God's 50,000 Watt Voice Of The North" - it was the only commercial station the FCC allowed to deliver point-to-point messages.  Folks would call or write and they would transmit the messages to people living in the bush.  It was also at night.
Answer: There are useful tidbits in all the answers so far.  Here are a couple more.  Not every ham has the good fortune to have conveniently spaced tall trees to hang horizontal antennas from.  On 80 meters to function well, a dipole antenna would be about 130 feet long (a half wave). Distance above ground for optimal performance would be the same distance.  Probably not practical for most hams.  The situation improves the higher in frequency you go--i.e 40 meters where the half wave length is about 66 feet with the corresponding reduction in optimal height.  I guess what I'm saying is that, on 80 put up a dipole and get it as high as you can.  It will still work at lower heights--just not as well.  A vertical on 80 is also probably also impractical (unless you use "tricks" which will limit it's performance) since the vertical radiator would need to be a quarter wavelength long (66 feet) and many, many ground radials which would also be about that long.  Commercially produced multi-band verticals make rather fantastic claims as to their performance. They tend to be poor performers when compared to a full sized horizontal antenna.  They're also outrageously expensive.  You can homebrew a dipole for far less than $50.00.
Comment: Thanks for your input, and welcome to ham.stackexchange.com!  Please consider taking [the tour](https://ham.stackexchange.com/help) to get the most from this site.
Comment: Thanks for taking the time to answer my question! I've since decided that the horizontal HF is better overall but haven't yet considered homebrewing my equipment.
Answer: It matters only for local RF interference purposes. Once the signal hits the ionosphere, the polarization is randomized, thus it really doesn't make a difference.
Polarization of RF Interference tends to be vertically polarized, but that's such a small effect that it really probably doesn't matter which way you do the antenna.
Answer: Very good answers posted about polarization. I must point out an important caveat about polarization - while not so important for distant skip contacts ... it IS a vital consideration for LOCAL contacts. Cost and convenience is a prime factor for the popularity of rooftop vertical HF antennae. If your local friends are using verticals - you need to also be on a vertical (polarization) otherwise they may not hear you clearly or at all. As noted in another answer, vertical does draw more interference in a typical cityscape, but it varies depending on your location and proximity to interference sources.
If local contacts are important, and if other locals are using verticals, then you should consider a vertical. If DX is more important, then other horizontal options present themselves (which may even work well for local contacts).
A different factor to consider is the construction of the particular vertical you intend to use. Some are simply a 50 ohm "dummy load" with a wavelength/fraction wire sticking out it. Some have grounding radials. Some have coils. Just classifying it a vertical antenna is not entirely accurate.
Comment: What is "local" on HF? That seems like it would depend on power, antenna height, and a few other factors...
Answer: If I could have only one antenaa, any antenna, it be a 150' Big Bertha with stacked tribanders :)
Before a good answer can be made, we need some more information:
1) What bands are you interested in working? 2) Can you get a horizontal antenna at least λ/4 high and preferably λ/2 high? 3) Do you have an antenna tuner?
If I were flat broke and had high trees, I would make a fan dipole with one leg on 80m/75m, one leg 40m (gives you 15m for free as it's the 3rd harmonic) and one leg 10m. Depending on the situation, you could probably pull 20m out of either 40m leg or 10m with a close enough match to not need a tuner.  Having one would tighten the match, but probably wouldn't make a noticable difference.  Not counting the optional tuner, you would be hard pressed to spend $50 on this solution.  You'd have resonant antennas on the primary bands and could work the world no problem.
If soldering 6 wires is a problem, and you had a tuner, a G5RV or clone would be an option.  It's an all band solution, but is a compromise on all bands and a tuner is required for a good match.  You can work a lot of countries with one, but it will set you back $75-$100 plus a tuner.
If I had no trees, or low trees or no good way to hang a dipole, I would go with a multiband vertical like the GAP Challenger DX.  It uses stub matching and gives a no tuner between than 1.5:1 on all the HF bands plus 6m and 2m.  It's a bit of a compromise on 80m and is worthless on 160m though.  It uses 3 couterpoise wires instead of a large radial field and you can work the work 40m and up no problem (I have one).  But it costs $350.  There are cheaper ones, but they are more and more of a compromise especially the ones that use coils to make up for their physical size.
I have both a vertical and dipoles and I find the noise difference to be negligible, but that's certainly something that is going to vary by location.  In a city or dense suburban area, RF trash from the neighbor's plasma TV might rule out a vertical (as a previous poster noted, most man-made RFI is vertically polarized).
Answer: Well, speaking from a budget point of view, you can cover 80-6 for $100 with a multiband OCF dipole, but any HF vertical is going to require a lot more budget than that - probably at least 5 times that much, and more if you need to bury radials.
Most everything posted here is not relevant in light of the enormous cost difference between a well-performing dipole and a well-performing vertical for HF.
Comment: Hustler 4BTV and a spool of wire for radials can be had for \$200. If you want more bands you can put a tuner on it, just like you'd be doing with a dipole covering 80m to 6m. You can put a tuner on a much cheaper monoband vertical, for that matter. Or haul a \$2 piece of wire vertically into a tree. Not sure "five times as much" is a fair comparison.
Comment: Why not hold the radials down with staples until the grass thatch grows over them? Or use a lawn edger?
Comment: Most of the expense from doing a vertical antenna *properly* comes from renting the equipment to *properly* install the radials. I don't know too many people who want to bury a dozen 20m long radials with a shovel.
Comment: @user2104506 Phil is correct. That's what I do at the end of my Beverage RX antennas, and I know many hams who have done that with TX antennas. **In a few weeks, the radials disappear into the lawn and are difficult to pull up**.  My last 2 verticals used just 2 elevated radials. [4 or 6 high enough to walk under is  plenty!](http://www.w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html). Scroll down about half way to the "Relevant links". **Also**, with only 12 buried radials at the base of a λ/4 vertical, you'll lose over half of your power in earth losses.
Comment: Above ground radials "high enough to walk under" are not only a maintenance nightmare but a safety and liability issue. And, you cannot know how many radials are required until doing a thorough soil study. The point of my post was not to say "you need 12 ground radials for any antenna," obviously.
Answer: Horizontal.
However, one of the exceptions is 160 meters. If you are mostly interested on making longer distance QSOs (especially DX) contacts on 160, vertical polarization is best on that band. Period.
Check out this page. In a nutshell: What is effective on 160m are vertically-polarized antennas for transmitting, using separate antennas for receiving.
Per W8JI on qrz.com:
"Nearly all especially successful stations on 160 use a vertically polarized antenna of some type for transmitting. That's just a fact."
"The fact is....... an Inverted L with 20 or more radials at least 50 feet and hopefully 100 feet long will absolutely smoke any normal height loop antenna or dipole antenna at nearly any distance on 160 meters. The possible exception is between 20 and 200 miles."
"I have a full size 160 dipole at 300 feet, and it is never really much better than a 1/4 wave vertical at any distance in any direction. As a matter of fact, the dipole is 10-20 dB weaker than the vertical off the dipole ends. The dipole only beats the vertical broadside to the dipole, and then only rarely!! And this is with the dipole 300 feet above ground."
"As a matter of fact a low full wave loop has no gain, any horizontal wire has increased earth induced loss as it is made longer when close to earth."
http://forums.qrz.com/showthread.php?t=260716&highlight=beverage

Having said that about 160 meters...
On 80 through 10, both vertical and horizontal antennas can be good choices. You should pick whichever is convenient to erect and/or will accomplish your objective.
Comment: Technically, 160m is MF. But many folks consider HF as being 160-10.


Iridescence In Cycles?

Question: Is it possible to create an iridescence shader in Cycles?
Specifically for something like DVDs, soap bubbles, engine oil, etc..
Comment: True iridescence probably isn't possible: http://blender.stackexchange.com/q/17/14
Comment: See also: http://blenderartists.org/forum/showthread.php?253312-Some-Cycles-Materials-1 and http://blenderartists.org/forum/showthread.php?312537-cycles-pearl-material-help and http://www.blendswap.com/blends/view/70401 and http://www.luxrender.net/wiki/Pearl_material
Comment: would an OSL shader be an acceptable answer?
Comment: @zeffii, it's worth a shot.
Answer: From your linked definition of iridescence:

Iridescence [is] the property of certain surfaces that appear to change color as the angle of view or the angle of illumination changes.

Thus, the following node setup should suffice:

If you're not familiar with node groups, this will create a new "node" called Iridescence that takes a base color parameter (you probably want white) and a factor parameter (which determines how strong the iridescence is; you probably want about 0.4) to output a color that you can put into a shader. You can see examples of how this works before.
The setup simply takes the dot product of the view vector and the surface normal and maps it to a spectrum. If you're not familiar with vector math, you can basically think of a dot product as a measure of how parallel two vectors are: the dot product of two perpendicular vectors is 0, while the dot product of two normalized parallel (or anti-parallel) vectors is 1.
You can put this node group in any shader and get a nice result. I tried it in a Diffuse BSDF, but putting it in a Glass BSDF might yield some nice bubble renders.
Here's an image of Suzanne wearing her iridescent cloak (the factor is set to 1.0 to exaggerate the effect):

Here's the factor turned down to 40% (lower works in better lighting setups, but my sky texture is blowing it out):
Comment: It's sometimes also nice to Add a magic or distorted noise texture to the Normal or Reflection coordinates
Comment: @DavidA.Lewis Node groups were [changed a lot in 2.67](http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.67/Node_Editor#Group_Interface). That **is** the expanded form, the nodes "group input" and "group output" are now part of the way node groups work (and can't be expanded).
Comment: Could you post an EXPANDED version of the node-setup in your iridescence shader?  I can't even guess at what is in "Group Input" and/or "Group Output"...Otherwise it LOOKS like a great shader... TIA...  :O)
Comment: @DavidA.Lewis please see my edit.
Comment: Why did you use the camera vector? How well would that work with something like a mirror in the scene? Should you perhaps use the incoming vector instead?
Answer: True iridescence is difficult to achieve using Cycles. However, there are ways you can fake the effects of iridescence by shifting the color slightly based on the object normals. This has the advantage of being highly customizable for your particular purpose and much faster than true iridescence would be.
Update: I was able to find an implementation of this using Cycles on this BA thread.
Here is the node setup:

And an example render using the above node setup with different values:

EDIT: Found a better implementation done directly in Cycles. The old BI node setup can be found here.
Comment: Noise Scale: 5 Million!?!? Is that necessary for faking some tiny surface geometry that creates iridescence? (Nice answer, btw)
Comment: The setup posted here is far from correct (I know because I'm the author of the mentioned thread). The noise scale only serves for sampling purposes, as we need different seeds for each sample, but as I mentioned in that same thread, the output values are not normalized, and create a strange bias in the wavelength distribution. For diffraction grating (CDs, DVDs, etc), I'd advise to use my OSL script (also in the thread), wich is more accurated and physically based.
Answer: This is where OpenShadingLanguage can step in. Using an OSL script you can get an iridescence effect.
Michel J. Anders has already done the hard work on his Small Blender Things blog with his surface iridescence shader. You may find some of his other scripts interesting as well.
For example:

Iridescence In Cycles?


openfire user statuses always offline

Question: Is there anything in particular I need to configure to get the users statuses working? All the users seem to be offline no matter what.
Chat seems to work fine, but obv it's not ideal not knowing who is online at any one time.
w://
Comment: Can you exchange IMs with those who appear to be offline?
Comment: yeah - it all works ok - they're just reported to be offline
Answer: Did you figure this out? I notice in my new install of openfire (windows service, using the build in hsqldb.) That when I log into the admin panel is shows what users are online, but spark shows users as offline. We can still chat with each other, but have no indication of who is online.
A work around is to have the users log off and log back in and re-add people as contacts. This solves the problem for a couple of days. (thus far in limited testing)
Answer: You should check if your users send presence stanzas. If so then openfire make them online automatically.
Answer: I was having this problem until I realized that I didn't have the group settings configured correctly. To have the contact list show up in some clients and to show online status, you have to enable contact list sharing and specify the contact list name. If you don't specify the list name it won't work:
You can see the below screenshot:

This is in the Users/Groups tab > Groups > Edit Group

openfire user statuses always offline


Facebook privacy settings

Question: Months ago I customized my privacy settings so that some of my Facebook friends wouldn't be able to see my future posts. Yet, one friend I specifically put under "don't share this with" category liked the picture I posted yesterday. How is it possible? First off, we have no friends in common. The picture was on my timeline and it was not shared by anyone.
Comment: I've noticed that once in awhile facebook automatically brings the privacy settings back to default "free for all". My recommendation, check and correct your settings regularly and don't trust facebook one bit.
Answer: Apart from what's already mentioned in the comments, it is possible that you have a friend tagged in the photo and he saw it because the photo appeared on the friend's timeline.

Facebook privacy settings