Hammocks Make Sleep Easier, Deeper - <AUTHOR> http://www.npr.org/blogs/health/2011/06/20/137300311/why-hammocks-make-sleep-easier-deeper?sc=tw <comment><USER2> I've been sleeping in a hammock every night for a little over a year now.

Hammocks are cold, that is the biggest problem. You also can't really just flop down on one and lounge out the same way that you can in a bed.

From a totally utilitarian standpoint of "place for sleeping", a hammock has some benefits. It's small, it's highly portable (mine fits in my backpack), and it is pretty comfortable.

In reality, though, most people use their beds for a lot more than sleeping. Reading in my hammock is pretty difficult, so is using my laptop if I want to type anything. You can't comfortably fit more than one person in one (unless you've got a garden hammock with spreader bars on it).

<comment><USER3> May I ask why you've been sleeping on a hammock?

<comment><USER2> It's a psychological hack.

Basically, by intentionally depriving myself of something, it stops being "normal" and becomes a luxury. I was at my parents' house for Christmas in December, and felt like I was at a 5 star hotel.

I've done similar "hacks" to my diet. I did a month where I ate nothing but rice and beans (a very very healthy dish, actually). The first week or so when I was finished with the experiment, everything I ate tasted _amazing_.

The car that I drive is fairly beat up; I drove my sister's car to San Diego a few months ago, and I might as well have been driving a Bentley. A CD player? I can listen to whatever music I want!? It doesn't rattle when I go over 55?!? I can hold a conversation inside without having to yell?? etc. etc.

Silly, I know, but effective.

<comment><USER4> "Silly, I know, but effective."

Absolutely not. You could try it the other way. Work harder to earn more money, to be able to buy better stuff to get the same fealing. ;)

<comment><USER5> Hardly. His method is steady state repeatable. Yours is progressive.

</comment></comment></comment></comment></comment><comment><USER6> Really misleading headline. The study wasn't about hammocks at all, just a normal bed that sways. Makes me think more of being on a boat. I haven't experienced the effect, but David Foster Wallace wrote about it: [http://www.harpers.org/media/pdf/dfw/HarpersMagazine-1996-01...](http://www.harpers.org/media/pdf/dfw/HarpersMagazine-1996-01-0007859.pdf)

(Not going to give the page number of the sleep thing because I believe everyone should read the whole thing :)

<comment><USER7> Why should we read the whole thing?

I read a few pages, and it's absolutely shit. This guy has a terrible attitude. Why would I read 20some pages about some guy bitching about cruise ships?

EDIT: I've actually _been_ on a cruise, so I can tell this is all just a bunch of (highly subjective) crap.

<comment><USER8> I appreciate that the writing style isn't for everyone, but he's not "some guy", he's one of the best writers of our time. Don't worry though, others have made your mistake: <http://kottke.org/11/04/infinite-jest-blindly-judged>

<comment><USER7> I'm not worried because I didn't make a mistake. I'm not surprised he's a popular author; "sign of the times." But thanks for the info.

</comment></comment></comment></comment><comment><USER9> I've been sleeping on a woven dried-grass mat for over 2 years. Best Sleep in my life.

It all started by accident when we moved bachelor-house and a grass mat was the only available sleeping spot left at 2am.

Benefits:

\- Insulated from cold floor - never gets too hot or too cold.

\- Keeps my spine fit; I've never had a better back in my life.

\- Feels really secure - That may have more to do with me being a 250lb fat guy.

\- Freedom to toss and turn as much as you want without worrying about whats happening beneath you.

\- You can literally crash onto the mat with your day's exhaustion and nothing will break. I've mastered the art of falling into it without breaking bones.

The hammock sounds positively uncomfortable and terrifying from where I'm coming from.

</comment><comment><USER10> When I was in Panama, in one of the places I went to, I had to sleep in a hammock, and it was hell! Really uncomfortable, my back hurt from being bent the whole night, and I kept waking up all the time because I couldn't find the right position. Also, I wasn't swaying, that might last for a few minutes only, but after you fall asleep, if you are not moving, you don't sway at all.

Even though it wasn't the best sleep, I could bear it. But the friend I was with couldn't take it, he wanted to leave at 5 in the morning the first night there, he was totally desperate.

From that experience I'd say there's no way hammocks make sleep easier.

<comment><USER11> This of course depends on the quality of the hammock, in much the same way that a poor mattress will make for a bad sleeping experience. I own a Warbonnet Blackbird hammock (<http://warbonnetoutdoors.com/blackbirds.php>) and it's extremely comfortable. They're one of the very best hammocks out there and are very popular with the backpacking crowd.

</comment></comment><comment><USER12> Here is a link to the article: [http://download.cell.com/current- biology/pdf/PIIS09609822110...](http://download.cell.com/current- biology/pdf/PIIS0960982211005392.pdf)

</comment><comment><USER13> The article says it "increased the length of N2 sleep, a form of non-REM sleep that takes up about half of a good night's rest." Presumably this is at the cost of REM sleep? How is this then a good thing?

<comment><USER14> It could also mean shorter N1 or N3 phases of non-REM sleep. From my limited understanding it seems like the subjects falling asleep faster would correspond to a shorter N1 phase, but I haven't read the paper yet.

</comment></comment><comment><USER15> Daunted by the cost of a mattress bed and the idea of hauling it up my fifth- floor walkup in Manhattan, I opted for an indoor hammock instead. It's been the best sleeping experience I've ever had.

I used to get lower back problems when sleeping on a mattress that have disappeared since sleeping in the hammock. There are no real pressure points and it supports your body perfectly.

blhack mentioned that hammocks get cold. This is true as they don't retain any heat. I use a 'maximum heat' twin-size down comforter when the temperature drops.

<comment><USER16> How do you mount it in your apartment?

<comment><USER17> More importantly, how do you have a girl over if you only have a hammock?

<comment><USER18> Put her on the sofa.

There is nothing romantic about sleeping.

</comment></comment></comment></comment><comment><USER19> A lot of long distance through-hikers on the Appalachian Trail here in the Eastern US use hammocks instead of tents. They're gotten a lot more popular due to the "lightweight" craze in backpacking (trying to shave every ounce off your full pack weight) and set up/break down a lot faster.

<comment><USER20> How do you use the hammocks in the snow though? (Don't know if this applies to the Appalachian Trail, but I know that sleeping in the snow happens on the PCT).

<comment><USER11> You use both an under quilt and a top quilt to insulate the hammock, which is of course suspended above the snow. I haven't tried that yet as I'm more of a fair weather camper, but comments on various hammock forums suggest that winter camping in hammocks is common.

<comment><USER19> A lot of hikers do that, or use a liner which is a lot like a sleeping bag, but attached to the hammock and unzips for cleaning.

</comment></comment></comment></comment><comment> n-ion "A dozen adult research subjects" :(

</comment><comment><USER21> I really want a hammock in my (small) office. Any great options?

<comment><USER3> I hear Hammock Huts is a good place, also Hammocks-R-Us on third. And then theres Swing Low, Sweet Chariot...

<comment><USER22> Matter of fact, they're all in the same complex; it's the hammock complex on third.

</comment></comment></comment><comment><USER23> I didn't realize you could buy a hammock for under $20: [http://www.amazon.com/Texsport-14258-La-Paz- Hammock/dp/B000P...](http://www.amazon.com/Texsport-14258-La-Paz- Hammock/dp/B000P9GZUA/ref=sr_1_1?ie=UTF8&qid=1308619592&sr=8-1)

Now does anybody know how/where I can get something that rocks/pulls my hammock back and forth?

<comment><USER14> Get a cat.

<comment><USER22> and enjoy being randomly clawed in the chest when sleeping

</comment></comment></comment><comment><USER24> I don't like how they basically squeeze around your body, wrapping you all up. It's hard to turn around or even just to the side.

I guess the article was more about the 4 second rocking motion, though, which sounds delightful just from description.

</comment><comment><USER25> This makes sense in that I have always found I sleep really well on small boats. I always assumed it was the sound of water lapping the hull lulling ones brain but the rocking of the boat might be what does it.

</comment><comment><USER26> How much better? Give me a number so I can judge if I think its relevant...

<comment><USER27> It seems that the main focus of the article is on the difference in brain activity, not the sleep time. I would imagine that the time to sleep is not as important as the quality of the sleep thus attained.

<comment><USER28> I agree, and as such this article leaves my main question unanswered: with a bed that rocks (or a hammock), could I get the same amount of rest in less time?

In other words, what is the ratio of sleeping hours in a non-moving bed to a rocking-bed?

<comment><USER29> > could I get the same amount of rest in less time?

I'm dubious of anything that claims to pull this off. My own failed attempts have convinced me that sleep is not something that can be lifehacked. There is some variation in sleep requirements between individuals, but you and I each have a number (probably ~8 hours) below which our bodies start getting cranky. There are loads of studies showing that any form of sleep deprivation -- and I would include here trying to optimize down your overall sleep time -- has reliable, long term negative consequences. What's more, there seems to be an unusual level of consensus on this subject. (I say 'unusual' because medical researchers never agree on anything. :-)

<comment><USER30> This is basically true, but it doesn't necessarily all have to come in one 8 hour shot. The past month I've been taking 10 minute naps once an hour from roughly an hour before lunch on through about 6 in the evening, and it makes my working hours much more focused and my after-work hours feeling much more refreshed.

<comment><USER26> That reminds me of a polyphasic sleeper than slept for 1 hour every 4 hours of something like that.

Then I asked him:

\- And at night?

\- At night I sleep!

</comment></comment></comment></comment></comment></comment><comment><USER31> Now we know why rocking babies to sleep works.

<comment><USER32> The article does say "It's not like rocking like you would see some mothers rocking their babies, it's more gentle.", which seems to imply this type of rocking is different?

</comment></comment><comment><USER33> So, is it possible to set up an indoor hammock in a small room?

<comment><USER34> Of course it is (my roommate and I set up two hammocks in our dorm room between the wall studs) however the article suggests that simple rocking (not necessarily 'hammocks') is the key. And doing _that_ is easier, in that you need only put your bed on a platform that can rock. (baby cradles have rounded ends sometimes for that).

<comment><USER35> How about sleeping on a water bed? Is that enough motion?

Mechanically pushing a waterbed would also be easier than making a bed rockable.

</comment></comment></comment><comment><USER36> This reaffirms my wanting to buy a house boat and live on it.

<comment><USER37> I live on a boat (a sailboat rather than a houseboat, but it rocks in more or less the same way) and I can confirm that it is awesome. This article makes me want to get one of those sleep-quantifying bracelets and graph boat sleep vs. land sleep.

</comment></comment><comment><USER38> Try this: <http://www.lebeanock.com/></comment>


Ask HN: We have an app. Now what's our niche?   - <AUTHOR>

The website: http://jellly.com/
Many web apps are heavily dependant on network effects, and are completely useless without a decent user base already in place. When faced with this issue, the common wisdom is to target a small niche at first. Over time, you can branch out to other users. There are many examples of this, such as Facebook starting with just Harvard students for example.
The strategy makes a lot of sense, but the question is what niche should one choose? In our particular case, we need to sign up people who browse many of the same web pages. This is necessary because our app, Jellly, is meant to suggest related links as users browse the web, so there better be other users who saw some of the same web pages earlier and already suggested related links.
The "hacker" niche, as represented by this community, may be a good choice here, but I'm not sure. We had thought about targeting bloggers, as they are often all looking at the same blog posts and articles; they provide free marketing and they could get into an app like this (it's much better than using track-backs for sure), and they'd be happy to get some traffic out of it too by linking their own posts to other relevant stuff on Jellly. But the overall blogosphere is huge; the target needs to be more focused than that at first. Hacker-bloggers?
To better understand Jellly and our problem, you could take a peek at our FAQ. It may be more instructive though to see the crappy demo app I threw together in a few hours for our (failed) YC application, as long as you don't consider it to be characteristic of the actual app. It really just demonstrates how it might work for finding content: http://prettyobscure.jellly.com/ <comment><USER2> I think it's a very interesting idea, but I definitely see your problem of how to get initial content. I think a good niche would be programmers of a certain language, maybe ruby, javascript (or even just jQuery). Try to hire a couple of the more popular bloggers in the space to start seeding it with data and promoting it some and I think it would take off. If I was looking at a certain rails plugin it would be really interesting to see a list of links to tutorials for that plugin as well as some competing plugins that I should checkout.

<comment><USER3> I agree with you. Programmers and bloggers are definitely the way to go.

</comment></comment><comment><USER4> Do you have any beta sign ups? If there is a recurring theme that might make it easy to select a niche. Another thing you can do is select a niche, any niche, that you are already active in, like gaming or cooking or something like that.

Hacker bloggers is not a bad place to start if you are already active on HN and other places. The only thing I would caution is that hackers tend to be much more critical than the average person. Like some are willing to be early adopters but others expect everything to be perfect. Expect to hear a lot of "You should fix this bug/implement that feature - it should be EASY!" I think that tech-savvy but non-hacker people might be more open to "Is this useful?" discussions.

As a side note I find your logo to be really unclear. Honestly I think you should change it if you want it to really catch on, but if you're not willing to do that, then you might put "jellli.com" text underneath it.

<comment><AUTHOR> We just started telling people about the site two days back via Facebook/StumbleUpon and I guess HN now, and we have just above 40 signups so far. Conversion is pretty low, but that's expected without any real content. Need to fix that, add the demo perhaps. Part of asking what stuff people are into is to try to find a recurring theme, so I totally agree about that.

I think your comments about hackers are on target mostly, but I don't mind the criticism. It's really better than having friends tell you how great what you made is.

The logo was not worked on too much, and I'm not exactly good with graphic design. I'm definitely going to get a professional to redo it in the future. I'm not sure it would make a huge difference to whether people sign up for beta, but I can see how it might.

</comment></comment><comment><USER5> I'm going to take a leap here, but I'm pretty sure that -- on the internet -- hacker/blogger/programmer/designers are not a 'niche'. There are numerous communities for all of these people. Instead you should focus on groups of people who have a hard time connecting. There are plenty of communities that have no real internet equivalent. A small list of actual niches:

\- UrbEx (Urban Exploration) \- Board Game Enthusiasts \- Cooking (This could be a big one. Food blogs are really popular, but disconnected.)

There are a lot of people out there, and if you can focus on long-term user acquisition (which rules out the 'try every new thing and then drop it a month later' tech crowd), you'll be a lot happier.

<comment><AUTHOR> Very interesting. I think it would be difficult to help create an internet presence for those who don't already have some, whether in a community or not. But in the case of disconnected blogs and other content, where a presence does exist, there may be great potential to help unify all the bits spread all over the web. I'll look into this more, but I may have a hard time finding appropriate niches.

By "niche", I had really meant a group of like-minded people. There may be a more appropriate word. I don't want to stick to a particular niche forever, but expand to all possible topics eventually. The "niche" is just required to make sure there are network effects. People who try a new thing every other month are ok with me, as long as they help bring in others who are more likely to stay. Besides, some tools are rarely dropped by the tech crowd if they are truly useful, and I would hope that my application fell into that category.

</comment></comment><comment><USER2> Site - <http://jellly.com/>

Demo App - <http://prettyobscure.jellly.com/>

clicky clickable links

</comment><comment><USER6> I think that it's a great idea. One thing that I'd like to comment on: crowdsourcing > algorithms, especially with social going mainstream now.

The demo was great, but I much prefer that it's a bookmarklet instead of an inline frame. "Related sites" is not something that I need to see all the time, and it takes away vertical screen real estate, which can be annoying to some users. If you're set on using a widget, use the side of the screen to maybe house a button, expandable on click.

<comment><AUTHOR> I agree about crowdsourcing > algorithms, obviously.

Yeah, I'm planning to have a bookmarklet, iframe and browser extension UIs all available. The final UI is in no way set, and probably won't look exactly like the demo. Lots of people don't know how bookmarklets work, but they'd know how to use the toolbar. And many people are wary of installing extensions still, so a web-only version is good to have. Only problem is the confusion having multiple interfaces may cause some people. Will have to A/B test and see.

BTW, do make sure you sign up, haven't gotten any more signups since a while back :-)

</comment></comment><comment><USER7> I think you've done this backwards... problems that need solving tend to come with their own niche - the people who want the solution.

Don't get me wrong, this is an interesting app, but I don't see a demand for it (people are more than happy with Google mostly), and I'm curious exactly how you'd expect to turn a profit with it as well? Adverts and mass adoption?

<comment><AUTHOR> _I think you've done this backwards... problems that need solving tend to come with their own niche - the people who want the solution._

I actually intentionally worded it backwards from the usual as a minor form of headline bait, which failed. The app really should have broad appeal among people who frequent the web in general. That group of people is just too varied and spread out to help each other find links through Jellly. Hence the need to focus on a smaller, more closely knit group.

Not all apps fit the "solve a pain point" model that paid web applications go through. While pain killers are great money makers for sure, sometimes you don't know you'd want to use an app till you've tried it and see why it would be useful. These apps have a lower chance to succeed I guess, but they can be great when they do.

I know there's nobody dying to have this service. But Twitter comes to mind as another application that people thought was mostly useless. That is, until some of them used it (I know most people still think it's useless, but many obviously don't).

Advertising fits perfectly here, since the service is there for relevant links. The advertising would consist of relevant text links, similar to search ads. Mass adoption would be necessary for large profits, but I believe it's possible to break even much earlier, using advertising networks to start advertising early on.

</comment></comment><comment><USER8> Why not do "Hacker News Readers" as a niche?

I'm just one data point... But, while I think I grok what you're doing, I'm not sure I grok why I should want it. When I read articles, maybe 1 out of 10 makes me want to explore further. When I do want to explore further, there's usually a pretty natural way to do it-- the google search box in my browser. Google uses the link graph to find stuff related to the keyword. You're proposing to have users do it, right? The Google path doesn't seem to be broken to me... Other than the rare time that I can't think up the right search phrase to get good results.

<comment><USER3> I'm sure you sometimes click on hyperlinks besides those that show up in search results. The point is to make navigation of that manner via related hyper-links better, which is somewhat orthogonal to search we think. Sure, you can search and find anything, but it's not quite the same as just browsing by clicking links.

 _Google uses the link graph to find stuff related to the keyword. You're proposing to have users do it, right?_

I'm proposing to have users create a new link-graph, separate from the web's own inherent link graph. Keywords have nothing to do with it. :) - Looks like my home page isn't as clear as I thought.

<comment><USER8> I'd suggest a screencast on how to use it. Is it a separate site? An add-on that allows me to explore/suggest sites based on what I'm currently viewing?

<comment><AUTHOR> I think I'll be adding my demo to the home page soon, once I polish it. Otherwise, it can be pretty confusing.

There is probably going to be more than one way to use it, but the main way would be a browser extension. A web toolbar is also going to be there for people who don't like installing extensions, to get them started fast. You can see the demo of that (only shows you how you might browse through, had no functionality to add links): <http://prettyobscure.jellly.com/>

Let me know if it makes any more sense after trying the demo :)

</comment></comment></comment></comment><comment><USER9> How about music bloggers? They generally are always looking for 'new artists like this one' or 'new blogs like this one.'

</comment><comment><USER10> I vote for web design community. Graphic design / photoshop / ajax tutorials are all over the place.

</comment><comment><USER11> Seed with Google related site search?

<comment><AUTHOR> I might if that didn't suck so bad. It's probably not allowed by them anyways, robot.txt and ToS.

<comment><USER12> seed with something hacked out of the Delicious API... see moreofit.com for an excellent example of what might be possible

<comment><AUTHOR> Yeah, I had looked into their API before and it's a good option. Using tags to figure out the related links could give decent results to start off with. The results will be suboptimal though, as any automated approach would be, since "relevance" is more complicated than simply having a few matching tags. I hadn't seen moreofit.com before, seems to give pretty good results, so I may have been underestimating how far you can take tag analysis.</comment></comment></comment></comment>


Show HN: Review my startup: Simponent Web Service Studio - <AUTHOR>

Link to signup: http://www.simponent.com/downloads/index.html
The big idea is using JSON based application description language(ADL, similar to WSDL) to define and model restful web service API. It is platform and language independent.
- Define request and response types in both XML and JSON formats
- Authentication standards such as OAuth 1.0a, OAuth 2.0 and HTTP basic authentication
- Web Service Error and HTTP status codes
Simponent web service studio is a software tool to help publish web service API more effectively, accelerate API development and deployment process. Once ADL file is defined for your web service, with the help of web service studio
- Instantly give your web service an interactive console.
- Access your web service from command line.
- API reference and documentation in HTML and PDF format
- More features like web service testing/monitoring, client languages binding will come
We have made some demos for facebook/twitter/github api. demo link: http://www.simponent.com
We're still in beta and are making a lot of changes but wanted to get some feedback as early as possible.
Thanks <comment><AUTHOR> clickable: <http://www.simponent.com></comment>


Better Geometry Through Graph Theory (2018) - <AUTHOR> http://ideolalia.com/2018/08/28/artifex.html <comment><USER2> One geometric model that actually handles numerical approximations is called exact geometric computation. It's pretty interesting and starts by explicitly tracking arithmetic errors in the operations you do. At its core it's a mix of interval arithmetics and multi-precision floating point. This is something you can do since the floating point implementations on most (all?) CPUs give you strong guarantees on the error bound of floating point arithmetic operations and these are usually within 1 ulp (unit in the last place) of the correct result. Now you have an interval for the result and can build your geometric constructs on interval arithmetic rather than classic, single point scalar arithmetic.

Geometry works with constructs, not numbers. An intersection is a construct, collinearity is a construct, orientation / handedness is a construct, etc. If you define your fundamental constructs to be rigorous then the algorithms you build on top will also be rigorous. If we consider the article's inside- outside test example, this result would be computed based on the intersections (intervals) we've computed. Since we know for sure the correct result is within our interval of error then inside-testing boils down to comparing intervals and we know there are three possible situations here: 1. [a, b] < [c, d]; 2 [a, b] > [c, d]; 3. [a, b] overlaps with [c, d]. In case 1 and 2 we have a robust conclusion and in case 3 we recompute the whole predicate with higher precision until it becomes decidable.

The golden standard for exact geometric computation is CGAL [1]. All the research around it is very interesting and refreshing to read.

[1] cgal.org

<comment><AUTHOR> Hi, author here. I looked into that side of things, but CGAL only offers exact precision implementations for lines and circular arcs. The fact that Bézier curves are left as an exercise for the reader is further proof of the disconnect between computational geometry and modern computer graphics.

<comment><USER3> I'm curious; I've played with OpenSCAD a little, which uses CGAL, and found it to be painfully slow (with no particular point of comparison). Do you think you have a way to do similar CSG calculations faster, or at least trade speed for accuracy or something?

<comment><AUTHOR> It's very plausible that these techniques could be used to fix the output of a CSG library that uses floating point math, but I'm not sure what the specifics would look like. If anyone has ideas in that vein, I'd be very interested to hear them.

<comment><USER3> I was thinking along the lines (based on skimming documentation) of CGAL using arbitrary precision integer based rationals, which are slow, and using floating point with the error correction might potentially be faster.

Unfortunately, it's probably way beyond my ability to delve in to it.

</comment></comment></comment></comment></comment><comment><USER4> Sounds like a reinvention of coedges to me, boundary representations track topology and geometry in separated structures. The approximation errors are always a nasty issue and that is the no trivial work on a BREP modeling libraries, for different edge cases you need different algorithms and maybe even transform the geometry into a different parameter space to minimize the approximation errors on computing an intersection between geometries.

<comment><USER5> I'm not familiar with coedges --- they sound like the darts in the dual map of a planar combinatorial map[1] to me. Do you know if they correspond like this?

In short, a combinatorial map is a graph along with a counterclockwise order of incident half-edges ("darts") at each vertex. This is exactly enough data to record the topological information about how a given connected planar graph is embedded in the plane. They also work for graphs in general oriented surfaces, with the proviso that the complement of the graph consists of a bunch of faces homeomorphic to disks. For example, no annulus faces.

When reading the article, it seemed like what the author was doing was to construct something like a combinatorial map from the purported intersections then use that to answer inside/outside questions. (A graph by itself is unable to answer these questions since it's merely abstract vertices and edges. While the code they use shows the use of graphs[2], the graphs contain the geometric information of the vertex locations, which sort of lets you work with it as if it were a combinatorial map.)

[1] [https://en.wikipedia.org/wiki/Combinatorial_map](https://en.wikipedia.org/wiki/Combinatorial_map)

[2] [https://github.com/lacuna/artifex/blob/master/src/io/lacuna/...](https://github.com/lacuna/artifex/blob/master/src/io/lacuna/artifex/utils/regions/Clip.java#L136)

</comment></comment><comment><USER6> Bivector.net

Implementing computer graphics should be done with geometric algebra.

I don't know anything about this field but I know the difference between a clean, consistent API and a random hodgepodge of hacks.

Since I don't know anything I'm not sure if GA allows you to avoid errors such as the one in the article but in typical HN fashion I'll be derailing with some left- field claim and a link to some other project.

<comment><USER7> It feels like lisp - neat, maybe has pedagogical value, does not really solve any hard problems and usually not worth the overhead. Yet I still want to like it.

<comment><USER8> I'm wondering where did you take the notion, that lisp doesn't solve any hard problems? History proves otherwise over and over.

<comment><USER7> Not knowing what you consider a hard problem, I think most of them are not of the kind that a language can do much about. It can easily be a drag though, for example by being too high-level and taking control away from the programmer when it's needed. I'm not saying it's necessarily a bad tool (lisp or GA). They are just tools, not magic, and tools don't solve hard problems.

<comment><USER9> Oh, tools definitely solve hard problems. It's just once you got the right tool for a hard problem, the hard problem ceases to be a hard problem.

<comment><USER10> Or perhaps, choosing the right tool can reveal that certain, select problems are not actually that hard.

And perhaps, certain other problems, like computational geometry, are in fact just really fucking hard, no matter how you express them. Having some familiarity with the space, where the only really quality implementations are a massive GPL research code base in C++ (CGAL) and commercial C Libraries (Parasolid, SMLib), I lean towards this view.

<comment><USER9> I have some familiarity with computational geometry myself. I've built myself the tools I need for it in pure Apple Metal, and it beats anything you can buy or get for free (for my particular needs).

<comment><USER10> Do you mean computational geometry for graphics applications (your mention of Metal suggests this)?

I'm referring to computational geometry for manufacturing and engineering simulation applications, which is an entirely different beast (in particular, accurately tracking topology is much more important, and generally requires arbitrary-precision floats for degenerate cases).

<comment><USER9> No, manufacturing and engineering, for example, computing the offset of a 3D-body represented by a surface. This benefited heavily from massive parallel computation via Metal.

I also implemented other algorithms from scratch for solid body operations, and here indeed arbitrary precision rationals were needed first, but then I could get it working with normal double arithmetic in a lot of cases later on; I didn't use Metal here though.

I find that libraries like CGAL etc. are just either too slow or not general enough for my purposes. The whole sector seems ripe for disruption via proper algorithms implemented on graphics cards.

<comment><USER10> If I were you I would try and look up who uses Parasolid then, because they charge a fuckton of money

<comment><USER9> Thx!</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment></comment>


Test-First Machine Learning - <AUTHOR> https://codingossip.github.io/2020/test-first-machine-learning/ <comment><USER2> This is fun. I managed a data entry project at a previous employer that was kind of like this.

We had non technical subject matter experts that I sneakily got to write several thousand unit tests. We had some quantitative and qualitative data we wanted annotated on a substantial dataset of scanned documents. I built a tool that let them type natural language descriptors for everything. I then converted that to javascript unit tests by way of some regex and coffeescript.

It was possible to bootstrap classifiers that way! Seems like kind of old tech in an era of unsupervised megaML, but I've not been using that part of my resume for a year or so.

</comment><comment><USER3> > Testing model implementation details such as statistical and mathematical > soundness are not part of the TFML strategy. Such details should be tested > separately and are specific to the family of the model under consideration.

For anyone who clicked this thinking this would be related to model validation, it ain't. The article is promoting test-driven development for systems that have an ML component.

</comment><comment><USER4> I think you missed TDD as in Test Driven Development.

The article mentions nothing about specific methodologies regarding testing in a ML context.

Maybe on the next article? :)

<comment><USER5> I understood the it more as a call for a test-first methodology than detailed instructions.

A blog series on the details would be great, though!

</comment></comment><comment><USER6> Testing model code tends to be very difficult unless you design your training loop with lots of abstractions and dependency injection which makes the code less explicit and difficult to understand. For example, try to look at the Tensorflow Estimator framework. Absolutely awful to use but is well tested.

<comment><USER5> The idea is not to test model code at all - the blog post explicitly mentions that this as an anti-pattern.

The tests aren't concerned with the technical details at all - they should test whether the models work, not how.

<comment><AUTHOR> Exactly. The tests are concerned with integrating the ML component into the broader picture of requirements and engineering. Engineers are not really interested in why the statistics of a model is failing. And should never be (that's why testing model internals in TFML is an anti-pattern)</comment></comment></comment>


Ask HN: How long before Google crawls your startup website? - <AUTHOR>

Hi guys, I finished up our initial version of the website my brother and I are building.
www.smitecamp.com
I added in all recommended SEO tags from SEOMoz and generated a sitemap and submitted to Google Webmaster tools. It's been 5 days now and we still haven't been crawled by Google.
Any idea on how long it takes for Google to actually show your pages? I even searched for an exact "smitecamp.com"  and it still shows the old domain-squatter type WHOIS pages. <comment><USER2> Submit a sitemap to Google Webmaster Tools for starters. Then try to get backlinks from other websites so Google can use an indexable path to your site.

If your site really is www.foobar.com, it appears to be blank right now.

<comment><AUTHOR> I already submmited a sitemap, but still no crawls. :/

And foobar is just dummy domain to explain my situation.

<comment><USER3> You could have just given actual name , google might have indexed it through this back link ;)

</comment></comment></comment><comment><AUTHOR> @Prashant: I added in the actual domain name, hopefully Google picks it up. :) Good idea!</comment>


Why I Ripped the Same CD 300 Times - <AUTHOR> https://john-millikin.com/%F0%9F%A4%94/why-i-ripped-the-same-cd-300-times <comment><USER2> In case anyone was wondering why a "red book" audio compact disc isn't designed to be resiliant in a way that is familiar to a modern technologist (or even compared to a CD-ROM disc) the basic reason is that the former is designed to stream with no buffering directly into a DAC chip built with technology from the late 1970s. It had to handle data rates that were incomprehensibly massive for the time, so only the most insanely basic error handling was feasible.

Whereas the "yellow book" CD-ROM standard got to take advantage of over four years of technology advancement. Plus it doesn't have a real time requirement, so there's plenty of time to calculate more advanced checksums and error correction codes.

In many respects, an audio CD is more like a vinyl record than a data storage format.

<comment><USER3> > In many respects, an audio CD is more like a vinyl record than a data > storage format.

The design is nearly identical to what one would get if one simply literally (almost) digitized a vinyl record. A single long spiral of data on a disk. The most significant shift is that vinyl records read from outside in, while audio CD's read from inside out. Even the method of manufacture is essentially a clone (audio CD's are "pressed" just like vinyl records are "pressed", just in different pressing machinery).

> built with technology from the late 1970s. It had to handle data rates that > were incomprehensibly massive for the time, so only the most insanely basic > error handling was feasible.

Yes, the limits of late 1970's technology had a huge impact on the overall design, but at the same time the design also took advantage of the fact that audio when being played back in real time is reasonably tolerant of a small level of error resulting from the read-off of the disk. Most listeners would never hear the random errors because they either are below the noise floor of the amplifier tech. at the time, or because the resulting analog wave was close enough to not be noticeably different.

<comment><USER2> > The most significant shift is that vinyl records read from outside in

Equally significant (and equally interesting) is how they spin. Whereas vinyl has constant _angular_ velocity—they spin at the same rate from beginning to end, resulting in lower information density as you get towards the inner grooves—audio CDs have constant _linear_ velocity, meaning that the rotational speed gradually changes as the disc is played so that the information density is equal from beginning to end.

For the era, this is very cool tech. (I'm also awestruck about how they managed to get the laser head alignment to work perfectly back then, it's practically magical.)

<comment><USER4> Techmoan did a video about a record that is recorded "backwards" to take advantage of the increasing fidelity in the outer grooves.

[https://www.youtube.com/watch?v=5Afikv6k1-c](https://www.youtube.com/watch?v=5Afikv6k1-c)

<comment><USER5> Techmoan's recent video on extended play (2.5 hour) CDs is also quite interesting.

[https://youtu.be/5fG1crhGqI0](https://youtu.be/5fG1crhGqI0)

</comment></comment></comment></comment></comment><comment><USER6> This is a little awkward. The Touhou album in question is already in the Touhou Lossless Music Collection (at least the last release: [http://www.tlmc.eu/2018/01/tlmc-v19.html](http://www.tlmc.eu/2018/01/tlmc-v19.html) since it's from 2005, it's probably been in most of them), and has track 3 ("The End of Theocratic Era" by "弘世"). I just checked the TTA and track 3 sounds fine.

If anyone is terribly curious what it sounds like, I've put up an OGG copy here: [https://www.dropbox.com/s/u88u1xpdmdxbqal/03%20%E5%BC%98%E4%...](https://www.dropbox.com/s/u88u1xpdmdxbqal/03%20%E5%BC%98%E4%B8%96%20-%20The%20End%20of%20Theocratic%20Era.ogg?dl=0)

Oh well. I'm sure it was a great learning experience anyway. :)

<comment><AUTHOR> Most of the TLMC rips are range rips with unclear CUE data, which makes it difficult or impossible to verify they were correctly ripped.

For this album in particular, the audio CRCs of the other tracks don't match up between TLMC and a fresh rip:

TLMC:

      01.wav: 9A5E3226
      02.wav: 577A675B
      03.wav: 3548C299
      04.wav: E5DEC006
      05.wav: D33AC4AE
      06.wav: 7427AC6F
      07.wav: 83A58517
      08.wav: 0DCA8419
      09.wav: 703BAEAC

My rip:

      01.wav: 565F2B5A
      02.wav: E916B3A2
      03.wav: A595BC09
      04.wav: D989F0D6
      05.wav: C6A2DD2B
      06.wav: C8403284
      07.wav: D01D6BC4
      08.wav: 8786C1AA
      09.wav: 1E3641DD

<comment><USER7> Is there such a thing as an audiodiff to tell how different they are to yours?

<comment><AUTHOR> Yes: you can use Audacity ([https://www.audacityteam.org/](https://www.audacityteam.org/)) to "diff" two waveforms by subtracting one from the other.

For comparing .wav files you can also treat them as plain binary data, and use standard diff tools. For example I used `cmp -l` to count differences between rips, and `vbindiff` to view them.

<comment><USER8> Thanks for mentioning vbindiff. I examine/compare binary files a lot (reverse engineering for security) and I've used a bunch of tools, but somehow I've never come across vbindiff.

</comment></comment></comment></comment></comment><comment><USER9> Tangentially related: I think this is the first time I see an emoji URL "in the wild", not as a proof of concept. I don't know how to feel about it.

<comment><USER10> Really not a fan. Makes the url impossible to type on desktop.

<comment><USER11> Will go one further: the use of emoji at all defeats the purpose of having a language and an alphabet.

<comment><USER12> You say that, and yet Egypt became an empire whose history has been saved 4000 years later thanks to a pictogram based language.

<comment><USER13> Egyptians hieroglyphics are phonograms though, not [very loosely defined] ideograms -- I thought that was the point about their translation, that people wrongly assumed they were pictorial ideograms.

</comment></comment></comment></comment></comment><comment><USER14> Awesome read! It's great to see someone faced with tech challenge and not back down. We need more of that.

For anyone interested, here are some links to the details of error-correcting codes (ECC) used on CD-ROM: \- [http://www.usna.edu/Users/math/wdj/_files/documents/reed- sol...](http://www.usna.edu/Users/math/wdj/_files/documents/reed-sol.htm) \- [http://www.multimediadirector.com/help/technology/cd- rom/cdr...](http://www.multimediadirector.com/help/technology/cd- rom/cdrom_spec.htm) \- [http://bat8.inria.fr/~lang/hotlist/cdrom/Documents/tech- summ...](http://bat8.inria.fr/~lang/hotlist/cdrom/Documents/tech-summary.html)

But I think CDDA possibly uses different (less) ECC... so info in links might not be 100% relevant.

It's a shame this cool tech is not being used anymore. As an information theorist, I used to be able to point to optical disks as an application of my field, and be like "see all that math is useful for something," but now I don't have anything shiny to point to anymore :(

<comment><USER15> > As an information theorist, I used to be able to point to optical disks as > an application of my field, and be like "see all that math is useful for > something," but now I don't have anything shiny to point to anymore

I strongly disagree, there's many shiny things you can point towards.

Point to a smartphone (and also the relevant sections of the LTE/HSPA/UMTS/WCDMA/GSM / 802.11 standards documents); there's a literal panoply of coding/error-correction maths that's crucial to every single one of those standards. You can actually go to the ETSI website and find the LTE standard and get free PDFs with the exact parameters of all the codes they use, in enough detail to reimplement them yourself.

In those standards, there's all sorts of lovely little state machines for coping with errors, like LTE's "HARQ loop" where your phone will tell the cell base station that it didn't receive a chunk of data correctly; at which point the tower will resend a _differently punctured_ version of the chunk of data, and your phone's modem will try to soft-decode the data with _both_ versions to work with. Oh, and that exchange (including processing on both ends and radio transmission latency) takes under 10 milliseconds to _complete_ \-- the standard places an exigent and strict deadline on how long your phone has to respond with its acknowledgement/request.

Also hard-drive platters are extremely shiny (more so than optical disks) and those also use error-correcting codes, as do SSDs. Did you know that bit cells in modern SSDs are so small that the number of electrons it takes to affect a measurable voltage difference for the sense amplifiers is _less than 100_ ([https://twitter.com/whitequark/status/684018629256605696](https://twitter.com/whitequark/status/684018629256605696))? All your data lives in those differences of tens of electrons per bit cell; no wonder there's ECC machinery hard at work in SSDs!

<comment><USER16> > _...like LTE 's "HARQ loop" where your phone will tell the cell base station > that it didn't receive a chunk of data correctly; at which point the tower > will resend a_ differently _punctured version of the chunk of data, and your > phone 's modem will try to soft-decode the data with both versions to work > with._

Cooool.

I googled "HARQ loop" and because I visit HN so much the first result was [https://news.ycombinator.com/item?id=11151232](https://news.ycombinator.com/item?id=11151232), so I learned that the data-processing portion (where the decode attempt is retried) must complete within 3ms!

I've been wondering for some time about good (bandwidth-efficient) ways to do error correction/recovery in the area of general-purpose high-efficiency byte transports, and just in case, wanted to put this here in case you're/anyone is interested. How good would it be to throw TCP's "flood of ACKs" out the window and instead compare frame checksums (is CRC32 good?) of every say 32 frames, and send a bitmask (in this case 8 bytes) every _n_ frames noting which were correct and which aren't? This would send ~32 times less data (and I just learned a TCP ACK is approx. 74 bytes! [https://stackoverflow.com/questions/5543326/what-is-the- tota...](https://stackoverflow.com/questions/5543326/what-is-the-total-length- of-pure-tcp-ack-sent-over-ethernet))

(My interest/focus is within the domain of good ideas lacking widepread implementation/uptake. I've found that these always seem to be hiding in the woodwork.)

<comment><USER17> Your TCP ACK approach is confusing. If you mean to check all the frames, but only say if they're OK every 32 frames that only makes sense if you somehow have a medium with high bandwidth AND high error rates. If your error rates are low conventional TCP will just send occasional ACKs saying e.g. "Yup, got the last 500 packets, keep it up".

But if your error rates are high and your bandwidth is high you should already know how to fix this and get very slightly less bandwidth without errors, so why is this suddenly TCP's problem and not your transmission medium?

<comment><USER18> Because I for one can't change the DOCSIS parameters my ISP set for the segment I am on, and neither can I affect radio communications reliability without impaired movement. While the error detection is rather weird, and a simple erasure code might well work better, this is a good idea.

<comment><USER16> Thanks for the suggestion. I've been meaning to take the time to stare at how erasure coding works and keep staring until my eyes stop glazing over and I get it :)

I replied to the parent comment, FWIW.

</comment></comment></comment></comment></comment></comment><comment><USER19> Xiph.Org has a command line program called cdparanoia, which is built with the same philosophy as Exact Audio Copy (EAC). The FAQ page explains a lot about why the program is necessary.

[https://www.xiph.org/paranoia/](https://www.xiph.org/paranoia/)

[https://www.xiph.org/paranoia/faq.html](https://www.xiph.org/paranoia/faq.html)

<comment><USER20> Thanks for the name drop. I went Linux-only on my primary laptop, but I still have a Windows 7 laptop with EAC installed that I dig out every time I buy a new CD and need to do a rip. Maybe I'll finally be able to put it to rest, soon.

<comment><USER21> I've found that EAC works really well in Wine, and it's still my favorite ripper, even on Linux. Similarly, Foobar2000 in Wine is the best Replaygain scanner/tagger.

</comment></comment></comment><comment><USER22> Whoa, this update is weird:

« EDIT: After further investigation, I no longer believe it's a factory defect. If I write the beginning or end of the affected track to a blank CD-R and rip it, the rip fails with the same error! Give it a try yourself with minimal.flac. »

[https://github.com/jmillikin/john- millikin.com/blob/master/%...](https://github.com/jmillikin/john- millikin.com/blob/master/%F0%9F%A4%94/why-i-ripped-the-same- cd-300-times/minimal.flac)

Uh... so what's going on there? Something that breaks the error correction algorithm, or what? Can anyone with a burner repro this?

<comment><USER23> _Uh... so what 's going on there? Something that breaks the error correction algorithm, or what?_

It is likely "weak sectors", the bane of copy protection decades ago and of which plenty of detailed articles used to exist on the 'net, but now I can find only a few:

[http://ixbtlabs.com/articles2/magia- chisel/index.html](http://ixbtlabs.com/articles2/magia-chisel/index.html)

[https://hydrogenaud.io/index.php/topic,50365.0.html](https://hydrogenaud.io/index.php/topic,50365.0.html)

[http://archive.li/rLugY](http://archive.li/rLugY)

<comment><USER22> OK, wow! So basically CDs are not capable of recording arbitrary data, or at least most burners will fail on certain inputs, and the song in question causes trouble. Fascinating!

</comment></comment></comment><comment><USER15> > It turns out you can't fix noisy data by intersecting it with a different- > but-related noise source.

No you actually can; it's called "soft combining": [https://en.wikipedia.org/wiki/Hybrid_automatic_repeat_reques...](https://en.wikipedia.org/wiki/Hybrid_automatic_repeat_request#Hybrid_ARQ_with_soft_combining) and it's a crucially important feature in high-performance air interfaces (like LTE).

<comment><USER24> That's kind of like how you can reduce noise in low light images by taking a series of photos and averaging them together.

<comment><USER25> I really don't think that's the same thing. Taking multiple shots of the same subject is just taking a shot with a really long shutter time, except in slices, a little bit at a time.

What OP was talking about was something akin to using the noise in a photo of one subject to reduce noise in another photo of a completely different subject but with the same camera.

That works, to a point, but not great.

<comment><USER26> In astro-photography, this is quite common. You take a series of normal images. You then cover the the lens, and take the exact same exposure. After a series of processing, the noise pattern from the dark frames is subtracted from the normal images. It works quite well.

</comment></comment></comment></comment><comment><USER27> This kind of obsessiveness was used to create the best values of Oink's pink palace - until that modern library of alexandria was burned down.

<comment><USER28> Followed by the loss of what.cd. It was truly one of the most impressive catalogs of information on the internet.

<comment><USER12> I really hope there are a few people still out there that have the full catalog of what.cd archived and either keep it alive by sharing it in the darker recesses of the internet, or are able to secure it somewhere.

There really needs to be a media museum, an international library of all that has ever been produced, from a hundred different recordings of the old composers to whatever crap your 15 year old neighbour is uploading to soundcloud.

<comment><USER29> If its anywhere like the scene and DCPP used to be then there's archivists who have the extremely rare content, including for example MP3.com rarities. A full archive is very convenient, but if you're a collector who's after certain rarities all it requires is a good network (or networking skills). Social network, and some bandwidth.

<comment><USER30> if you know where those MP3.com archivists hang out - a friend of mine is after a particular disc.

</comment></comment></comment></comment></comment><comment><USER23> This is very similar to the technique used by [https://en.wikipedia.org/wiki/SpinRite](https://en.wikipedia.org/wiki/SpinRite)

 _This didn't seem to be an issue of wear or damage – the CD itself was probably defective from the factory._

It would be very interesting to look at the surface of the disc under a microscope, to see if you can find the defective area --- knowing which track it's in, you can determine the approximate diameter at which it occurs, and then rotate around that diameter looking for abnormalities. The pits and lands are invisible to the naked eye but easily viewable with a light microscope:

[https://en.wikipedia.org/wiki/File:CD_Pits_at_6.25x_Magnific...](https://en.wikipedia.org/wiki/File:CD_Pits_at_6.25x_Magnification.jpg)

At 1200 bits/mm linear density of a CD, the 5KB (40Kbit) defective section will correspond to ~33mm of track --- probably quite obvious if it is a physical defect. (A "logical" defect, where the bits are OK but the ECC is wrong, will not be apparent at the physical level.)

<comment><AUTHOR> I don't have the equipment for this, but it might not be needed. The disc has writing that goes "through" the top cover, such that you can read the text by holding the disc up to a normal lightbulb.

The text is across the entire diameter and I don't know why it would cause problems for only this track. Possibly the shape of the text?

edit: photo [https://i.imgur.com/fdtAAPG.jpg](https://i.imgur.com/fdtAAPG.jpg)

<comment><USER23> That could be an area with insufficient contrast, a similar problem that early drives had when CD-Rs started appearing. In that case I would've tried a mirror or black pad (about the only thing those audiophile "disc mats" are good for...) on the top, to shift the offset level.

Note that CD uses 780nm infrared so what the human eye sees is not necessarily what the drive sees --- this is why "transparent" or "black" CDs work.

</comment></comment></comment><comment><USER31> Fry's Electronics should pay this man for the plug at the end. He made a good case to go there if you need to conduct an experiment requiring an unreasonable number of unique disk drives right now.

</comment><comment><USER32> This reminds me of trying to rip Paul Simon's Concert in the Park some number of years ago. Everytime I ripped it, there was a minor glitch in The Obvious Child at 2:02-2:03. I also heard it on the CD. So I tried different drives, different machines, Linux, Windows, iTunes, Exact Audio Copy, etc., to no avail.

Finally I reassesed my assumptions and found a copy of the track in the wild -- hey! Same glitch. Then I emailed a friend who I knew also had a copy of the album -- same glitch!

Eventually found an obscure forum where someone also complained about the same glitch.

I always wonder how that made it out of the studio -- was it a glitch in the recording equipment of the concert? Surely they used multiple recorders?

<comment><USER32> Found a VHS video -- [https://www.youtube.com/watch?v=obNpTfAga6M](https://www.youtube.com/watch?v=obNpTfAga6M) \-- the artifact isn't there, so it must have been in post production?

</comment></comment><comment><USER33> What a beautiful story of devotion! Imagine someone going to this much trouble over your work, it's quite impressive.

I used to worry about this kind of thing, using cdparanoia and so forth on Linux to manage my music. When I went Apple I eventually went iTunes, which is a mixed blessing. I feel like it has made me able to appreciate more music more easily by lowering the cost barrier, but it has reduced the amount I appreciate an album substantially. And it's hugely inconvenient when they disable my account for strange reasons or my internet connection vanishes. So I may return to manual management someday.

<comment><USER34> I recently found a backup of an old portable mp3 player and realized that the manual curation and limited storage really made me appreciate my collection more. Gave me a wonderful warm feeling going through that collection.

</comment></comment><comment><USER35> Out of pure curiosity, what's the prison sentence in the US for ripping a CD 300 times? A few years multiplied by 300?

<comment><USER36> Zero, because it isn't illegal to rip CDs.

<comment><USER37> Fun times. Once upon a time I was working at a university in New Zealand. At that time Apple had created a way to legally stream your iTunes catalog to other LAN users—mostly as a way of enabling the college campus music sharing experience without the illegalities of OG Napster, Limewire, and the ilk.

I got a nastygram from the IT department for sharing my iTunes catalog. I replied that it was my understanding that the iTunes streaming was legal. They concurred, but said that format-shifting my albums had been illegal. I countered that I format shifted my CDs in the US, where it was legal.

In the end, the IT security people agreed that I was probably totally legal, but they asked me to please refrain from leaving the iTunes sharing turned on because it made their lives hard. That was a compelling argument, and so I turned off iTunes sharing. :-)

EDIT: I should note that format shifting was later made legal in NZ last I knew. Hopefully it still is.

<comment><USER38> What is "format shifting"?

</comment></comment></comment></comment><comment><USER39> If you want to avoid having to do this you might want to look in to embedding error correction data on to your CD/DVD (or even on to separate media) at burn time, using dvdisaster:

[https://en.wikipedia.org/wiki/Dvdisaster](https://en.wikipedia.org/wiki/Dvdisaster)

</comment><comment><USER40> "This sort of thing is common when buying used CDs, especially if they need to transit a USPS international shipping center. "

As a used CD seller who often ships internationally with no complaints, I am interested in learning more about what is behind this statement.

<comment><AUTHOR> In my experience: as the box size gets bigger, the treatment gets rougher. Single CDs in bubble wrap envelopes come through fine, as do small hardwall boxes. CDs in medium boxes (10-20 CDs) often arrive with box damage and maybe some torn internal packaging. I once used a shipping aggregator that put 50 CDs in one box, they were so banged up that I had to buy replacement jewel cases.

If you ship CDs, I have only one request: please please do _not_ put bubble wrap _inside_ the jewel case! Some sellers do this and it just destroys those little plastic retainer teeth.

<comment><USER40> Thanks for the feedback. Bubble envelopes don't really protect CD jewel cases very well, which is why I create my own packaging by wrapping the cases individually in recycled cardboard. Simple and cheap. CDs are amazingly resilient and with a proper polishing machine scratches can be completely removed without changing the data on the disc. It is damage on the non-playing side of CDs which is impossible to recover from.

</comment></comment></comment><comment><USER41> Touhou! I dont see that everyday on hackernews.

<comment><USER42> You do not really see it lately.

<comment><USER43> the time of utter popularity has passed, but it is still plenty popular both in the world and Japan specifically. There's a few dozens conventions and Touhou music concerts/DJ-ing per year, the biggest of which is the Reitaisai and its accompanying events. And a new spin-off game is coming out this August!

</comment></comment></comment><comment><USER44> As a side note and not necessarily related, one of the devices I keep using in case I need to read a (data, not music) CD is a very, very old CD-ROM drive, of the original rype that use a caddy cartridge, 1x in speed, with a SCSI connection.

Till now it never failed on discs that current, modern and newish fevices had issues with.

</comment><comment><USER45> It kind of makes you want to hear this track he was so dedicated to getting off the CD.

<comment><AUTHOR> I don't know how much piracy discussion is permitted on HN, so I'll be brief: this album is contained in the lossless music collection.

<comment><USER46> Touhou is, iirc, basically completely public domain. It's a gigantic, bizarre diaspora fueled entirely by dedicated fans.

Everybody who thinks that copyright is required should see the success of 2hu.

<comment><USER6> > Touhou is, iirc, basically completely public domain.

Zun actually does have a semi-formal license/terms of use (it primarily bans commercial use but also quite a bit of other stuff, much of which I think goes ignored): [http://touhou.wikia.com/wiki/Touhou_Wiki:Copyrights](http://touhou.wikia.com/wiki/Touhou_Wiki:Copyrights) [https://www.animenewsnetwork.com/news/2011-02-14/tohou- proje...](https://www.animenewsnetwork.com/news/2011-02-14/tohou-project- creator-restricts-commercial-works-anime)

<comment><USER47> AFAIK the whole doujin scene is all about "go on, violate our copyrights but don't complain when people violate yours".

ZUN's blanket ban on commercial distribution makes it really difficult and expensive to legally obtain anything when the only distribution channels are specialized doujin stores -- it's still commercial, but the ones getting the profits are various middlemen and not the arrangers and performers.

</comment></comment></comment></comment></comment><comment><USER48> >It turns out you can't fix noisy data by intersecting it with a different- but-related noise source.

This doesn't make sense to me. Why didn't this work?

</comment><comment><USER9> I have about 200 DVDs, most 10 years old. Probably 1/4 is unreadable by now: MacOS does not recognise the disk when inserted (oddly enough, much older CDs still are).

The data is not terrible valuable and probably already mostly stored elsewhere, but I'd like to give it a try. Is there hope for ddrascue? I've had mixed results in the past. Are there better alternatives?

<comment><USER49> If you take away one thing from the article it is this; try different readers. Some readers perform far better than others. I have one 'magic' DVD reader that will overcome damage that makes most other drives choke with errors, and the result is usually a flawless rip.

<comment><USER30> AVSForum, Doom9, Redump and Hydrogenaudio are all good places to find out about these drives, too.

</comment></comment></comment><comment><USER30> I wonder if what.cd has this album before it was razed.

A lot of value was lost when that site went down.

<comment><USER50> [https://interviewfor.red/](https://interviewfor.red/)

<comment><USER30> Oh jesus. These guys thought the what.cd interview was too easy, didn't they?

<comment><USER51> It's substantially the same interview.

</comment></comment></comment></comment><comment><USER52> Thrift stores are a cheaper and very reliable alternative to Fry's, if you are ever looking for one. I've never not seen a CD/DVD player at a thrift store.

<comment><USER53> Good point, I'm curious if older drives produce better results. I remember some discussion 10-15 years ago saying that modern floppy drives were junk compared to older drives. The argument was that the prices dropped so much that build quality also suffered. I wonder if the same applies to CD/DVD-ROM drives.

<comment><USER52> My experience is that the more off-brand the player, the more lenient it is with what it will play. I had a crap Lite-On that would play anything.

</comment></comment></comment><comment><USER54> The jump between the 53th and 54th rips is very suspicious! Didn't you look more into it to try and explain it?

</comment><comment><USER38> It has always struck me as odd that the powers that be have yet to figure out how to harness the love (obvious since they toil to preserve these media works at the best possible quality, albeit illegally) of data hoarders.

</comment><comment><USER55> I see that no one has mentioned yet cuetools and the cuetools database in this thread. That seems the perfect tool for this kind of repairing (provided someone else has ripped an accurate version in advance, of course)..

</comment><comment><USER56> Take a look at: [http://ixbtlabs.com/articles2/magia- chisel/index.html](http://ixbtlabs.com/articles2/magia-chisel/index.html)

</comment><comment><USER57> doesn't abcde[1] do this?

[1][https://abcde.einval.com/wiki/](https://abcde.einval.com/wiki/)

</comment><comment><USER58> Cool URL

</comment><comment><USER59> I wonder if the HDD the author used to store those bits is also having read errors, which the drive is correcting on the fly.

<comment><AUTHOR> It's very likely! There's a couple approaches one can take to detect this:

* The rip log generated by EAC includes a CRC of the audio data. I can calculate this independently to ensure the data is the same as what EAC wrote.

* The rip log itself has a checksum that can validate the CRCs are intact.

* I archive my rips in Google Cloud Storage along with a sha256. If my NAS's copy goes bad I can fetch the backup, and validate that it's the original data.

<comment><USER60> Alternatives or additions:

* Store par2 parity information alongside your cloud storage and/or NAS: [https://github.com/Parchive/par2cmdline](https://github.com/Parchive/par2cmdline)

* Use a file system with strong data checks and repairability, basically meaning, ZFS with a sufficient redundant set up. "zpool scrub" can do wonders, and you can guarantee backups to a different pool are identical to the source.

<comment><USER29> In the scene they've used SFV (CRC32) for ages. It works very well and quick except it isn't useful against tampering. PAR2 provides additional parity, and it also useful if for Usenet. You can also use RAID. For example, Synology NAS easily allow RAID1 plus btrfs.

</comment></comment></comment></comment><comment><USER61> What I'd do is the same thing I do for scratchy records. Look for the scratch in a waveform editor. Interpolate the data across the scratch using cubic splines. You can also paste in data from the other channel if it is similar enough.

<comment><USER62> I thought the point was to get the _actual_ data back (not that you could with records).

<comment><USER61> True, but he was using statistical techniques, which are not guaranteed to produce the actual data.

My technique is akin to what an artist would do in "restoring" a damaged photograph. Often the glitch is only one data value being off, and it does produce an audible click.

</comment></comment></comment><comment><USER63> Not including a sample of the audio he/she ripped in an article such as this should be considered a type of crime.</comment>


Making a Single-Serving Site - <AUTHOR> http://petersobot.com/blog/a-site-for-dinner/

<comment><USER2> I have been after a site that does what A Meal for Me does for so long - thanks!

It would be nice if it would tell me if there are other recipes with the same ingredients, rather than just taking me back to the beginning when I click "Not your taste? Try again", but apart from that it's fantastic.

By the way, the "get in touch" link at the end needs a "mailto:" bit - it's a 404 currently.</comment>


Printing with Love: The Art of Letterpress Printing - <AUTHOR> http://craftsmanship.net/the-art-of-letterpress-printing/ <comment><USER2> This article writes the basic step of type creation, punchcutting, out of the story. It's crucial and exacting, while many other letterpress process are mechanical and unskilled. A lot of letterpress fans seem to fetishize processes and outcomes that are actually not that special.

See [http://www.dandad.org/en/kumar-and-lost-art- punchcutting/](http://www.dandad.org/en/kumar-and-lost-art-punchcutting/)

Edit: here's a better video: [https://m.youtube.com/watch?v=eExllUeGtvc](https://m.youtube.com/watch?v=eExllUeGtvc)

<comment><USER3> It also only makes passing reference to more modern photopolymer plates as well as the Linotype[1] method of setting type. My grandfather started is career in the newspaper business and they were still using a linotype back then.

[1] [https://en.wikipedia.org/wiki/Linotype_machine](https://en.wikipedia.org/wiki/Linotype_machine)

<comment><USER2> There's a recent socumentary on the linotype machine. [http://www.linotypefilm.com/](http://www.linotypefilm.com/)

The mechanical binary coding of matrices used to return them to their hoppers via the distribution mechanism is intriguing.

</comment></comment></comment><comment><USER4> > Once the paper has been completely coded for type casting, it looks like a > roll of Morris code, or a Western Union telegram from someone who couldn't > stop talking.

Morris code? _Morris_ code‽ I'm pretty sure that he means _Morse_ code!

</comment><comment><USER3> A friend and a cousin both own letterpresses. They - like most small printers - create digital files and have photopolymer plates created to print from. Easier, safer and less toxic than casting lead or other more traditional methods.

</comment><comment><USER5> The video - [https://vimeo.com/98092121](https://vimeo.com/98092121) at the bottom of the page is a sublime watch, damn I love old machinery when I was really young I worked in a printing factory that had stuff like that (some of the machines had mounts where the axles from a steam engine used to be attached...).

Just incredible ingenuity.</comment>


Why Google May Want Yelp - <AUTHOR> http://news.cnet.com/8301-30684_3-10418625-265.html?tag=newsLeadStoriesArea.1

<comment><USER2> It would be interesting to see IAC spin-off Citysearch or Urbanspoon and get acquired by Garmin.

</comment><comment><USER3> Data.

It's why Google wants everything.</comment>


Fire balloon - <AUTHOR> https://en.wikipedia.org/wiki/Fire_balloon <comment><USER2> Less well known is Operation Outward, England's cheap, scrappy balloon program that actually got results:

[https://en.wikipedia.org/wiki/Operation_Outward](https://en.wikipedia.org/wiki/Operation_Outward)

</comment><comment><USER3> > On March 10, 1945, one of the last paper balloons descended in the vicinity > of the Manhattan Project's production facility at the Hanford Site. This > balloon caused a short circuit in the power lines supplying electricity for > the nuclear reactor cooling pumps, but backup safety devices restored power > almost immediately.

<comment><USER4> What are the chances?!

</comment></comment><comment><USER5> These are still (very rarely) found by hikers in the pacific northwest (source: i'm a bomb tech).

Other relevant / weird WWII reading: [https://en.wikipedia.org/wiki/Bat_bomb](https://en.wikipedia.org/wiki/Bat_bomb) (US program) [https://en.wikipedia.org/wiki/Anti- tank_dog](https://en.wikipedia.org/wiki/Anti-tank_dog) (Russian program)

<comment><USER6> And let's not forget more recent efforts:

[https://en.wikipedia.org/wiki/Military_dolphin](https://en.wikipedia.org/wiki/Military_dolphin)

</comment></comment><comment><USER7> There's a really great Radiolab episode on this topic: [http://www.radiolab.org/story/fu-go/](http://www.radiolab.org/story/fu-go/)

<comment><USER8> Such a fantastic episode. This was the first episode I had ever listened to of Radiolab.

</comment></comment><comment><USER9> This was the test subject for trying to prove any conflict situation could be turned into a wargame:

[https://boardgamegeek.com/boardgame/34117/winds- war](https://boardgamegeek.com/boardgame/34117/winds-war)

</comment><comment><USER10> If you remember the old show Ripley's Believe it Or Not hosted by Jack Palance they did an episode on the Fire balloon. There were cases where unknowing hikers happened upon them in the west coast and some with horrible consequences as mentioned in the article.

[https://en.wikipedia.org/wiki/List_of_Ripley%27s_Believe_It_...](https://en.wikipedia.org/wiki/List_of_Ripley%27s_Believe_It_or_Not!_episodes_\(1982%E2%80%9386\))

</comment><comment><USER11> So here's a weird idea: Could Roswell 1947 simply have been one of these balloons? Maybe the US was trying to improve those balloons with some, at the time, experimental material.

<comment><USER12> The Roswell incident was a balloon, but it's highly unlikely that it was a fire balloon. Most contemporary analysis points to the Roswell incident being caused by one of the Project Mogul balloons [1]. Project Mogul was a top- secret (at the time) project to detect Soviet atomic bomb tests by listening for their shock waves with very sensitive microphones. These microphones were mounted on large hexagonal discs, which, when viewed by an untrained eye, looked like a flying craft of some sort.

[1] [https://en.wikipedia.org/wiki/Project_Mogul](https://en.wikipedia.org/wiki/Project_Mogul)

</comment></comment><comment><USER13> _Eventually, an Army fighter managed to push one of the balloons around in the air and force it to ground intact, where it was examined and filmed._

Wait, what, how??

<comment> david-given Wingtip turbulence, most likely.

In the UK during WWII, it was discovered that you could flip over a V1 flying bomb by putting the wingtip of your plane just under the wingtip of the bomb, at which point its gyro would get confused and it would flip over and spiral into the ground. This was apparently much safer than shooting them because otherwise you'd get caught in the shockwave when they exploded (they were bombs, after all).

Here's a terrible Daily Mail article, but it's got the famous photos of someone actually doing it.

[http://www.dailymail.co.uk/news/article-1384740/Kate- Middlet...](http://www.dailymail.co.uk/news/article-1384740/Kate-Middleton- pays-tribute-pilot-knocked-V1-missiles-course-planes-wing.html)

BTW, wikipedia claims that in at least one case the V1 engine quenched after tipping, at which point it regained controlled flight and came down to a safe landing near Tilburg, where it was captured for examination...

</comment></comment><comment><USER14> Yeah, one of these landed in Omaha, NE damaging a clock in Dundee neighborhood. Not terribly deadly, but it made press.

</comment><comment><USER15> New front-end framework?</comment>


The Best Way to Create a Static Site for Your Side Project (for Developers) - <AUTHOR> https://www.indiehackers.com/@realseanp/the-best-way-to-create-a-static-site-for-your-side-project-for-developers-59bf34146c <comment><USER2> Why not use github pages, surge.sh, gitlab pages etc? There are a billion guides to do that</comment>


Upworthy Traffic Gets Crushed By Facebook Feed Changes - <AUTHOR> http://growthhackers.com/facebook-changed-how-the-news-feed-works-and-huge-website-upworthy-suddenly-shrank-in-half-business-insider/

<comment><USER2> Until recently, Upworthy was without a doubt the most significant source of noise in my Facebook feed. Glad to know there will be somewhat less of that going forward.

</comment><comment><USER3> ...couldn't happen to a nicer site.</comment>


Why Star Citizen Is Likely Going to Be a Complete Disaster - <AUTHOR> http://www.reaxxion.com/10195/why-star-citizen-is-likely-going-to-be-a-complete-disaster <comment><USER2> Classic Derek Smart, starts the conversation by claiming to be respectful to everyone, then essentially threatening to fight anyone who disagrees with him. Oh, he hedges and calls it "attacks", but if you don't know Mr. Smart, you don't know that he's always treated any disagreement as an "attack".

It's hard to take him seriously. His incoherent, perhaps schizophrenic rambling and threats towards his detractors over the years have certainly soured me. I mean, even here and now, in one sentence he tries to say his games were "popular", but "never caught on." What does that even mean?

>> The first game in the series was released back in 1996. Let that sink in.

Let it sink in that these games were unplayable. Not just unplayable in the sense that they were "boring" or "really buggy". I mean unplayable in the sense that, even if everything were working as intended, the intended operation was _designed to be unplayable_.

For example, the game actually requires us to go into a (poorly hidden) menu, find the crew member, and tell them to go eat, so they don't starve to death. Does the admiral of any fleet, or even the captain of any ship, contact every ensign under their charge personally and tell them to go hit the chow line? The games are not simulations of space combat, they aren't simulations of managing space fleets, they're simulations of Derek Smart's ultimate fantasy: being a complete control freak.

I can't finish reading this. This is supposed to be a criticism of Star Citizen, judging from the title, but all it's managed to do for the first 5000 words is go on about how great and visionary is Lord Derek Smart.

Some things never change.

<comment><USER3> You brought me back to the 90's there for a second. The Game God flamewars of old were so entertaining. :-)

<comment><USER4> I had the privilege of being personally flamed by Derek Smart on Usenet in the mid-'90s.

If achievements had been a thing back then, and had Usenet had them, that would definitely have been one.

</comment></comment></comment><comment><USER5> He may certainly be right; _Star Citizen_ comes across as an insanely ambitious project. But I confess that when I realized this critique was written by the Battlecruiser guy, I jokingly thought: "Well, if anyone knows about overpromising and underdelivering on space combat sims..."

<comment><USER6> > I jokingly thought: "Well, if anyone knows about overpromising and > underdelivering on space combat sims..."

That was kinda the thrust of his article—he's got a history of trying to do what Star Citizen is claiming it'll be, and it's taken him years and never really been that successful. So he sees what's coming out of their dev team, and recognizing the challenges he's had.

</comment></comment><comment><USER7> I never thought much of Derek Smart, especially after being suckered by the promise of no less than three of his hideously broken excuses for games, but writing for a shitty neoreactionary Gamergate site[1] is perhaps the absolute low of his abysmal career (congrats, Derek, now you've literally shared a banner with such gems as "Why We Need To Fight Against Transgender Acceptance"), to say nothing of the massive pot-kettle color comparison involved.

[1] [http://wehuntedthemammoth.com/2014/11/12/rooshs-reaxxion- dou...](http://wehuntedthemammoth.com/2014/11/12/rooshs-reaxxion-douchebag- non-gamer-starts-gaming-website-for-douchebags/)

<comment><USER8> If we're going to be judging news outlets by the worst opinion piece they've ever published, then let's be consistent: most if not all American newspapers have published torture apologia. Would you condemn someone published on Huffington Post for sharing a banner with "In Defense of Torture"[1]?

If not, why?

[1] [http://www.huffingtonpost.com/sam-harris/in-defense-of- tortu...](http://www.huffingtonpost.com/sam-harris/in-defense-of- torture_b_8993.html)

<comment><USER9> I think that's an accidental red herring. Let's try judging this news outlet by their policy, instead:

"Reaxxion is a gaming site for men that was created as a reaction to extremists infiltrating and corrupting video game journalism. It aims to be a community of men who want to discuss gaming without being fed propaganda or labeled sexist because of their interest in specific kinds of gaming entertainment."

I would assume that women are allowed to read the articles, but it doesn't sound like women are encouraged to comment on them. Personally, I have zero time for that kind of crap.

Hm...

On reflection, I also think there's a relevant difference between judging a news outlet by the _worst_ opinion piece they've ever published and judging a news outlet by the _average_ opinion piece they publish. The latter action is also useful for gauging the quality of the site's policy.

<comment><USER8> >On reflection, I also think there's a relevant difference between judging a news outlet by the worst opinion piece they've ever published and judging a news outlet by the average opinion piece they publish. The latter action is also useful for gauging the quality of the site's policy.

Good point, assuming the median article on Reaxxion is awful, not just a few outliers. (This assumption is likely true, IMHO)

<comment><USER9> Thanks! I really wish this piece had been published somewhere else; while the author comes with his own baggage there'd have been a better chance of real discussion that way. C'est la vie, and thanks again for listening.

</comment></comment></comment></comment></comment><comment><USER10> Derek Smart certainly has his own history but his remarks are spot on. Scope creep went out of control fairly early on, I backed this game expecting a spiritual sequel to Freelancer which I felt was a realistic goal. At the time, I was not aware of Robert's history of being removed from the Freelancer project due to delays. However, even in the case of Freelancer I was sold on Freelancer due to some of Robert's promises and quite surprised when the released version was missing many of the promised features. CIG wanting to build and rent out their own motion capture studio to third parties and selling ships for exorbitant pricing left a bad taste in my mouth early on. I will be happy if Star Citizen ends up being a modern Freelancer but I fear many will be sorely disappointed.

</comment><comment><USER11> He has a point and the domain expertise/experience but he doesn't say whether the failure of Star Citizen will involve Chris Roberts running around the internet and getting in massive flamefests with random users and threatening to sue everyone all while claiming all sorts of improbable qualifications. Or whether it will inspire parodies like this:

[https://www.youtube.com/watch?v=NtB_jvznaNM](https://www.youtube.com/watch?v=NtB_jvznaNM)

We can only hope!

</comment><comment><USER12> Derek Smart criticizing a space sim game about being overly ambitious? Now I've seen everything.

<comment><USER13> Did you read the article? His point is that having failed to manage scope several times he has developed an eye for it.

That's kind of what I was hoping from Chris Roberts when I backed. I knew he had issues managing scope before and I was hoping this was going to be a more experienced Chris Roberts focused on shipping working software and not selling more things he is going to have to develop.

The timeline isn't so much what bothers me it's the threat of running out of funding. CIG is not transparent about burn rate so it's hard to tell how much runway they have although they claim they have it covered, but the numbers don't make sense to me.

</comment></comment><comment><USER14> I almost stopped reading the piece as soon as I figured out who the author was; I initially missed the byline in the left column. I never had any problem with Derek Smart's games -- I tried BC3000 around 1999-2000 and just didn't get into it -- but I found his online antics and personality off-putting. I skipped a great deal of the chest-beating in the article to get to the actual meat.

It seems odd to be in agreement with Derek Smart, but I think he's right. Chris Roberts didn't stop at simply promising the moon; he's teasing the Oort Cloud at this point.

</comment><comment><USER15> Chris Roberts is working on his magnum opus. I have very little faith in anyone claiming that this guy is going to tank the effort. Also, I have to wonder if this dude has paid any attention to the COPIOUS amount of world detail being dumped into the universe, or actually played in _any_ of the released fighting sandbox, or paid a visit to CIG's offices (since you can, you know, drop by for a visit to see how development is going).

Disclosure: I have thrown a few thousand dollars into the Star-Citizen-shaped hole.

<comment><USER16> Actually he isn't saying he is going to tank it at all.

He said that the current project is impossible and the only way to complete anything is to fix the scope.

However his prediction is that once they try and fix the scope the backlash will be terrible.

<comment><USER15> Sorry, I worded my comment rather poorly. I meant to say that I think CR has been handling things very well so far, and I personally believe that he has the experience necessary to keep things under control during this process, and to make SC an historically-good game, with a long, successful life. Those are the odds I'm playing.

</comment></comment></comment><comment><USER17> Elite Dangerous, however, is fantastic if anyone was looking to scratch that space flight sim itch.

<comment><USER15> Haha! Excellent.

</comment></comment><comment><USER18> I feel lucky not to have given money to Star Citizen. When it started out, I was hoping for something that included deep space exploration - but it appears that it's basically just a really expensive combat sim. If there are plans for that, I've certainly not heard about them and everything about the ship design so far points toward a combat sim only.

In the meantime, I see $400 dollar ship models and have to wonder: who buys this stuff?

<comment> mkr-hn People privileged enough to have $400 to throw at a game.

</comment></comment><comment><USER19> Wow! Derek has been entertaining me online for nearly thirty years now and instead of that realization making me feel old, it actually makes me feel kind of young. The parts without the words "I" or "me" sprinkled all over them made it an insightful article from someone who's opinion is based on substantial knowledge of this subject. Good or bad. Hi Derek, I know you must be reading these :)

</comment><comment><USER20> Derek Smart?! It must have been at least 15 years since I last heard of him. He was pretty insufferable back in the usenet days, and still doesn't seem to have gotten noticeably less full of himself. An article supposedly about Star Citizen seems to actually be mostly about himself.

But if his point is that this is a niche of massive egos and impossible ambitions leading to failed games, there might be something to that.

</comment><comment><USER21> This is an opinioned based comment.

This piece reminds me of Trump's blustery presidential candidate announcement.

<comment><USER22> Probably the most accurate description of the article so far.

</comment></comment><comment><USER23> It only took him 15 years to stop calling himself "Doctor Derek Smart" \- good for him!

<comment><USER4> But did he ever apologize to the Coke machine?

</comment></comment><comment><USER24> "[Derek Smart]. Now that's a name I've not heard in a long time...a long time."

</comment><comment><USER22> Just to share here in case you don't want to read the article... the tl;dr version is accurately summed up as: 33% "I'm the greatest at this", and 67% "Star Citizen isn't gonna work because I can't see how (and remember, I'm the greatest)".</comment>


Ray-Casting Tutorial for Game Development and Other Purposes (1996) - <AUTHOR> http://permadi.com/1996/05/ray-casting-tutorial-table-of-contents/ <comment><USER2> Excellent resource, I remember browsing it many years ago - glad to see it's still online!

Also check out this other nice raycasting tutorial: [http://lodev.org/cgtutor/raycasting.html](http://lodev.org/cgtutor/raycasting.html)

<comment><USER3> These (lodev and permadi tutorials) were indispensible to me when I was working on my game engine, which used delta force style raycast terrain -- there are extremely few resources on that concept, sadly. Fortunately for us all, archive.org exists to preserve the few articles from the 90s on the subject.

<comment><USER2> Yes, it's amazing how many game development techniques appeared and faded out in the 90s, in that window of time between fast-enough CPUs and affordable GPUs. I have a copy of the Black Art of 3D Game Programming on my shelf and it's full of awesome tidbits.

I recently browsed flipcode.com and sadly parts of it are broken and only available thanks to the Internet Archive.

<comment><USER3> While I can still reply to this post I thought I would just mention that of these 3 resources, permadi, lodev, and flipcode, www.flipcode.com was the most important for understanding how to do heightmap terrain in a raycaster, like how Comanche and Delta Force did it.

Those are just for understanding, to go deeper, into code, perhaps the most important thing I found was here:

[http://rainmak3r.altervista.org/voxel/ukvoxel.htm](http://rainmak3r.altervista.org/voxel/ukvoxel.htm)

if anything is broken I believe archive.org has copies of the zip files as well, not just the html.

Just wanted to stick it here so perhaps someone else will find it easier to find, it took me a lot of googling and wandering through abandoned forums, looking for out-of-print books that no one has bothered to digitize, etc.

</comment></comment></comment></comment><comment><USER4> Why do all these great retro game dev articles get posted this time of year? Don't you guys know I have real side projects to work on. I get caught in an endless dive, peeling back layers of abstraction. This is exactly what got me hooked on development in the first place. I love it.

</comment><comment><USER5> I saw a brief demo on this on MDN and it's super neat. It was basic just layers but cool nonetheless.

</comment><comment><USER6> I absolutely love this tutorial. I followed it many years ago to create a simple raycaster, then extended it to have a ton of features like reflections, sprites, variable height walls etc.

Thank you F. Permadi for the good times!</comment>