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Typical time-of-flight 3D laser scanners can measure the distance of 10,000~100,000 points every second. Time-of-flight devices are also available in a 2D configuration. This is referred to as a time-of-flight camera. Triangulation Triangulation based 3D laser scanners are also active scanners that use laser light to probe the environment. With respect to time-of-flight 3D laser scanner the triangulation laser shines a laser on the subject and exploits a camera to look for the location of the laser dot. Depending on how far away the laser strikes a surface, the laser dot appears at different places in the camera's field of view.
This technique is called triangulation because the laser dot, the camera and the laser emitter form a triangle. The length of one side of the triangle, the distance between the camera and the laser emitter is known. The angle of the laser emitter corner is also known. The angle of the camera corner can be determined by looking at the location of the laser dot in the camera's field of view. These three pieces of information fully determine the shape and size of the triangle and give the location of the laser dot corner of the triangle. In most cases a laser stripe, instead of a single laser dot, is swept across the object to speed up the acquisition process.
The National Research Council of Canada was among the first institutes to develop the triangulation based laser scanning technology in 1978. Strengths and weaknesses Time-of-flight and triangulation range finders each have strengths and weaknesses that make them suitable for different situations. The advantage of time-of-flight range finders is that they are capable of operating over very long distances, on the order of kilometres. These scanners are thus suitable for scanning large structures like buildings or geographic features. The disadvantage of time-of-flight range finders is their accuracy. Due to the high speed of light, timing the round-trip time is difficult and the accuracy of the distance measurement is relatively low, on the order of millimetres.
Triangulation range finders are exactly the opposite. They have a limited range of some meters, but their accuracy is relatively high. The accuracy of triangulation range finders is on the order of tens of micrometers. Time-of-flight scanners' accuracy can be lost when the laser hits the edge of an object because the information that is sent back to the scanner is from two different locations for one laser pulse. The coordinate relative to the scanner's position for a point that has hit the edge of an object will be calculated based on an average and therefore will put the point in the wrong place.
When using a high resolution scan on an object the chances of the beam hitting an edge are increased and the resulting data will show noise just behind the edges of the object. Scanners with a smaller beam width will help to solve this problem but will be limited by range as the beam width will increase over distance. Software can also help by determining that the first object to be hit by the laser beam should cancel out the second. At a rate of 10,000 sample points per second, low resolution scans can take less than a second, but high resolution scans, requiring millions of samples, can take minutes for some time-of-flight scanners.
The problem this creates is distortion from motion. Since each point is sampled at a different time, any motion in the subject or the scanner will distort the collected data. Thus, it is usually necessary to mount both the subject and the scanner on stable platforms and minimise vibration. Using these scanners to scan objects in motion is very difficult. Recently, there has been research on compensating for distortion from small amounts of vibration and distortions due to motion and/or rotation. When scanning in one position for any length of time slight movement can occur in the scanner position due to changes in temperature.
If the scanner is set on a tripod and there is strong sunlight on one side of the scanner then that side of the tripod will expand and slowly distort the scan data from one side to another. Some laser scanners have level compensators built into them to counteract any movement of the scanner during the scan process. Conoscopic holography In a conoscopic system, a laser beam is projected onto the surface and then the immediate reflection along the same ray-path are put through a conoscopic crystal and projected onto a CCD. The result is a diffraction pattern, that can be frequency analyzed to determine the distance to the measured surface.
The main advantage with conoscopic holography is that only a single ray-path is needed for measuring, thus giving an opportunity to measure for instance the depth of a finely drilled hole. Hand-held laser scanners Hand-held laser scanners create a 3D image through the triangulation mechanism described above: a laser dot or line is projected onto an object from a hand-held device and a sensor (typically a charge-coupled device or position sensitive device) measures the distance to the surface. Data is collected in relation to an internal coordinate system and therefore to collect data where the scanner is in motion the position of the scanner must be determined.
The position can be determined by the scanner using reference features on the surface being scanned (typically adhesive reflective tabs, but natural features have been also used in research work) or by using an external tracking method. External tracking often takes the form of a laser tracker (to provide the sensor position) with integrated camera (to determine the orientation of the scanner) or a photogrammetric solution using 3 or more cameras providing the complete six degrees of freedom of the scanner. Both techniques tend to use infra red light-emitting diodes attached to the scanner which are seen by the camera(s) through filters providing resilience to ambient lighting.
Data is collected by a computer and recorded as data points within three-dimensional space, with processing this can be converted into a triangulated mesh and then a computer-aided design model, often as non-uniform rational B-spline surfaces. Hand-held laser scanners can combine this data with passive, visible-light sensors — which capture surface textures and colors — to build (or "reverse engineer") a full 3D model. Structured light Structured-light 3D scanners project a pattern of light on the subject and look at the deformation of the pattern on the subject. The pattern is projected onto the subject using either an LCD projector or other stable light source.
A camera, offset slightly from the pattern projector, looks at the shape of the pattern and calculates the distance of every point in the field of view. Structured-light scanning is still a very active area of research with many research papers published each year. Perfect maps have also been proven useful as structured light patterns that solve the correspondence problem and allow for error detection and error correction. [24] [See Morano, R., et al. "Structured Light Using Pseudorandom Codes," IEEE Transactions on Pattern Analysis and Machine Intelligence. The advantage of structured-light 3D scanners is speed and precision. Instead of scanning one point at a time, structured light scanners scan multiple points or the entire field of view at once.
Scanning an entire field of view in a fraction of a second reduces or eliminates the problem of distortion from motion. Some existing systems are capable of scanning moving objects in real-time. VisionMaster creates a 3D scanning system with a 5-megapixel camera – 5 million data points are acquired in every frame. A real-time scanner using digital fringe projection and phase-shifting technique (certain kinds of structured light methods) was developed, to capture, reconstruct, and render high-density details of dynamically deformable objects (such as facial expressions) at 40 frames per second. Recently, another scanner has been developed. Different patterns can be applied to this system, and the frame rate for capturing and data processing achieves 120 frames per second.
It can also scan isolated surfaces, for example two moving hands. By utilising the binary defocusing technique, speed breakthroughs have been made that could reach hundreds to thousands of frames per second. Modulated light Modulated light 3D scanners shine a continually changing light at the subject. Usually the light source simply cycles its amplitude in a sinusoidal pattern. A camera detects the reflected light and the amount the pattern is shifted by determines the distance the light travelled. Modulated light also allows the scanner to ignore light from sources other than a laser, so there is no interference.
Volumetric techniques Medical Computed tomography (CT) is a medical imaging method which generates a three-dimensional image of the inside of an object from a large series of two-dimensional X-ray images, similarly Magnetic resonance imaging is another medical imaging technique that provides much greater contrast between the different soft tissues of the body than computed tomography (CT) does, making it especially useful in neurological (brain), musculoskeletal, cardiovascular, and oncological (cancer) imaging. These techniques produce a discrete 3D volumetric representation that can be directly visualised, manipulated or converted to traditional 3D surface by mean of isosurface extraction algorithms. Industrial Although most common in medicine, Industrial computed tomography, Microtomography and MRI are also used in other fields for acquiring a digital representation of an object and its interior, such as non destructive materials testing, reverse engineering, or studying biological and paleontological specimens.
Non-contact passive Passive 3D imaging solutions do not emit any kind of radiation themselves, but instead rely on detecting reflected ambient radiation. Most solutions of this type detect visible light because it is a readily available ambient radiation. Other types of radiation, such as infra red could also be used. Passive methods can be very cheap, because in most cases they do not need particular hardware but simple digital cameras. Stereoscopic systems usually employ two video cameras, slightly apart, looking at the same scene. By analysing the slight differences between the images seen by each camera, it is possible to determine the distance at each point in the images.
This method is based on the same principles driving human stereoscopic vision. Photometric systems usually use a single camera, but take multiple images under varying lighting conditions. These techniques attempt to invert the image formation model in order to recover the surface orientation at each pixel. Silhouette techniques use outlines created from a sequence of photographs around a three-dimensional object against a well contrasted background. These silhouettes are extruded and intersected to form the visual hull approximation of the object. With these approaches some concavities of an object (like the interior of a bowl) cannot be detected. Photogrammetric Non-Contact Passive Methods (Photogrammetry) Photogrammetry provides reliable information about 3D shapes of physical objects based on analysis of photographic images.
The resulting 3D data is typically provided as a 3D point cloud, 3D mesh or 3D points. Modern photogrammetry software applications automatically analyze a large number of digital images for 3D reconstruction, however manual interaction may be required if a software cannot automatically solve the positions of the photos which is an essential step in the reconstruction pipeline. Various commercial packages are available including PhotoModeler, Geodetic Systems, Autodesk ReCap and RealityCapture. Close range photogrammetry typically uses a handheld camera such as a DSLR with a fixed focal length lens to capture images of objects for 3D reconstruction. Subjects include smaller objects such as a building facade, vehicles, sculptures, rocks, and shoes.
Camera Arrays can be used to generate 3D point clouds or meshes of live objects such as people or pets by synchronizing multiple cameras to photograph a subject from multiple perspectives at the same time for 3D object reconstruction. Wide angle photogrammetry can be used to capture the interior of buildings or enclosed spaces using a wide angle lens camera such as a 360 camera. Aerial photogrammetry uses aerial images acquired by satellite, commercial aircraft or UAV drone to collect images of buildings, structures and terrain for 3D reconstruction into a point cloud or mesh. Reconstruction From point clouds The point clouds produced by 3D scanners and 3D imaging can be used directly for measurement and visualisation in the architecture and construction world.
From models Most applications, however, use instead polygonal 3D models, NURBS surface models, or editable feature-based CAD models (aka Solid models). Polygon mesh models: In a polygonal representation of a shape, a curved surface is modeled as many small faceted flat surfaces (think of a sphere modeled as a disco ball). Polygon models—also called Mesh models, are useful for visualisation, for some CAM (i.e., machining), but are generally "heavy" ( i.e., very large data sets), and are relatively un-editable in this form. Reconstruction to polygonal model involves finding and connecting adjacent points with straight lines in order to create a continuous surface.
Many applications, both free and nonfree, are available for this purpose (e.g. GigaMesh, MeshLab, PointCab, kubit PointCloud for AutoCAD, Reconstructor, imagemodel, PolyWorks, Rapidform, Geomagic, Imageware, Rhino 3D etc.). Surface models: The next level of sophistication in modeling involves using a quilt of curved surface patches to model the shape. These might be NURBS, TSplines or other curved representations of curved topology. Using NURBS, the spherical shape becomes a true mathematical sphere. Some applications offer patch layout by hand but the best in class offer both automated patch layout and manual layout. These patches have the advantage of being lighter and more manipulable when exported to CAD.
Surface models are somewhat editable, but only in a sculptural sense of pushing and pulling to deform the surface. This representation lends itself well to modelling organic and artistic shapes. Providers of surface modellers include Rapidform, Geomagic, Rhino 3D, Maya, T Splines etc. Solid CAD models: From an engineering/manufacturing perspective, the ultimate representation of a digitised shape is the editable, parametric CAD model. In CAD, the sphere is described by parametric features which are easily edited by changing a value (e.g., centre point and radius). These CAD models describe not simply the envelope or shape of the object, but CAD models also embody the "design intent" (i.e., critical features and their relationship to other features).
An example of design intent not evident in the shape alone might be a brake drum's lug bolts, which must be concentric with the hole in the centre of the drum. This knowledge would drive the sequence and method of creating the CAD model; a designer with an awareness of this relationship would not design the lug bolts referenced to the outside diameter, but instead, to the center. A modeler creating a CAD model will want to include both Shape and design intent in the complete CAD model. Vendors offer different approaches to getting to the parametric CAD model. Some export the NURBS surfaces and leave it to the CAD designer to complete the model in CAD (e.g., Geomagic, Imageware, Rhino 3D).
Others use the scan data to create an editable and verifiable feature based model that is imported into CAD with full feature tree intact, yielding a complete, native CAD model, capturing both shape and design intent (e.g. Geomagic, Rapidform). For instance, the market offers various plug-ins for established CAD-programs, such as SolidWorks. Xtract3D, DezignWorks and Geomagic for SolidWorks allow manipulating a 3D scan directly inside SolidWorks. Still other CAD applications are robust enough to manipulate limited points or polygon models within the CAD environment (e.g., CATIA, AutoCAD, Revit). From a set of 2D slices CT, industrial CT, MRI, or Micro-CT scanners do not produce point clouds but a set of 2D slices (each termed a "tomogram") which are then 'stacked together' to produce a 3D representation.
There are several ways to do this depending on the output required: Volume rendering: Different parts of an object usually have different threshold values or greyscale densities. From this, a 3-dimensional model can be constructed and displayed on screen. Multiple models can be constructed from various thresholds, allowing different colours to represent each component of the object. Volume rendering is usually only used for visualisation of the scanned object. Image segmentation: Where different structures have similar threshold/greyscale values, it can become impossible to separate them simply by adjusting volume rendering parameters. The solution is called segmentation, a manual or automatic procedure that can remove the unwanted structures from the image.
Image segmentation software usually allows export of the segmented structures in CAD or STL format for further manipulation. Image-based meshing: When using 3D image data for computational analysis (e.g. CFD and FEA), simply segmenting the data and meshing from CAD can become time consuming, and virtually intractable for the complex topologies typical of image data. The solution is called image-based meshing, an automated process of generating an accurate and realistic geometrical description of the scan data. From laser scans Laser scanning describes the general method to sample or scan a surface using laser technology. Several areas of application exist that mainly differ in the power of the lasers that are used, and in the results of the scanning process.
Low laser power is used when the scanned surface doesn't have to be influenced, e.g. when it only has to be digitised. Confocal or 3D laser scanning are methods to get information about the scanned surface. Another low-power application uses structured light projection systems for solar cell flatness metrology, enabling stress calculation throughout in excess of 2000 wafers per hour. The laser power used for laser scanning equipment in industrial applications is typically less than 1W. The power level is usually on the order of 200 mW or less but sometimes more. From Photographs See Photogrammetry. Applications Construction industry and civil engineering Robotic control: e.g.
a laser scanner may function as the "eye" of a robot. As-built drawings of bridges, industrial plants, and monuments Documentation of historical sites Site modelling and lay outing Quality control Quantity surveys Payload monitoring Freeway redesign Establishing a bench mark of pre-existing shape/state in order to detect structural changes resulting from exposure to extreme loadings such as earthquake, vessel/truck impact or fire. Create GIS (geographic information system) maps and geomatics. Subsurface laser scanning in mines and Karst voids. Forensic documentation Design process Increasing accuracy working with complex parts and shapes, Coordinating product design using parts from multiple sources, Updating old CD scans with those from more current technology, Replacing missing or older parts, Creating cost savings by allowing as-built design services, for example in automotive manufacturing plants, "Bringing the plant to the engineers" with web shared scans, and Saving travel costs.
Entertainment 3D scanners are used by the entertainment industry to create digital 3D models for movies, video games and leisure purposes. They are heavily utilized in virtual cinematography. In cases where a real-world equivalent of a model exists, it is much faster to scan the real-world object than to manually create a model using 3D modeling software. Frequently, artists sculpt physical models of what they want and scan them into digital form rather than directly creating digital models on a computer. 3D photography 3D scanners are evolving for the use of cameras to represent 3D objects in an accurate manner.
Companies are emerging since 2010 that create 3D portraits of people (3D figurines or 3D selfies). Law enforcement 3D laser scanning is used by the law enforcement agencies around the world. 3D Models are used for on-site documentation of: Crime scenes Bullet trajectories Bloodstain pattern analysis Accident reconstruction Bombings Plane crashes, and more Reverse engineering Reverse engineering of a mechanical component requires a precise digital model of the objects to be reproduced. Rather than a set of points a precise digital model can be represented by a polygon mesh, a set of flat or curved NURBS surfaces, or ideally for mechanical components, a CAD solid model.
A 3D scanner can be used to digitise free-form or gradually changing shaped components as well as prismatic geometries whereas a coordinate measuring machine is usually used only to determine simple dimensions of a highly prismatic model. These data points are then processed to create a usable digital model, usually using specialized reverse engineering software. Real estate Land or buildings can be scanned into a 3d model, which allows buyers to tour and inspect the property remotely, anywhere, without having to be present at the property. There is already at least one company providing 3d-scanned virtual real estate tours. A typical virtual tour would consist of dollhouse view, inside view, as well as a floor plan.
Virtual/remote tourism The environment at a place of interest can be captured and converted into a 3D model. This model can then be explored by the public, either through a VR interface or a traditional "2D" interface. This allows the user to explore locations which are inconvenient for travel. Cultural heritage There have been many research projects undertaken via the scanning of historical sites and artifacts both for documentation and analysis purposes. The combined use of 3D scanning and 3D printing technologies allows the replication of real objects without the use of traditional plaster casting techniques, that in many cases can be too invasive for being performed on precious or delicate cultural heritage artifacts.
In an example of a typical application scenario, a gargoyle model was digitally acquired using a 3D scanner and the produced 3D data was processed using MeshLab. The resulting digital 3D model was fed to a rapid prototyping machine to create a real resin replica of the original object. Michelangelo In 1999, two different research groups started scanning Michelangelo's statues. Stanford University with a group led by Marc Levoy used a custom laser triangulation scanner built by Cyberware to scan Michelangelo's statues in Florence, notably the David, the Prigioni and the four statues in The Medici Chapel. The scans produced a data point density of one sample per 0.25 mm, detailed enough to see Michelangelo's chisel marks.
These detailed scans produced a large amount of data (up to 32 gigabytes) and processing the data from his scans took 5 months. Approximately in the same period a research group from IBM, led by H. Rushmeier and F. Bernardini scanned the Pietà of Florence acquiring both geometric and colour details. The digital model, result of the Stanford scanning campaign, was thoroughly used in the 2004 subsequent restoration of the statue. Monticello In 2002, David Luebke, et al. scanned Thomas Jefferson's Monticello. A commercial time of flight laser scanner, the DeltaSphere 3000, was used. The scanner data was later combined with colour data from digital photographs to create the Virtual Monticello, and the Jefferson's Cabinet exhibits in the New Orleans Museum of Art in 2003.
The Virtual Monticello exhibit simulated a window looking into Jefferson's Library. The exhibit consisted of a rear projection display on a wall and a pair of stereo glasses for the viewer. The glasses, combined with polarised projectors, provided a 3D effect. Position tracking hardware on the glasses allowed the display to adapt as the viewer moves around, creating the illusion that the display is actually a hole in the wall looking into Jefferson's Library. The Jefferson's Cabinet exhibit was a barrier stereogram (essentially a non-active hologram that appears different from different angles) of Jefferson's Cabinet. Cuneiform tablets The first 3D models of cuneiform tablets were acquired in Germany in 2000.
In 2003 the so-called Digital Hammurabi project acquired cuneiform tablets with a laser triangulation scanner using a regular grid pattern having a resolution of . With the use of high-resolution 3D-scanners by the Heidelberg University for tablet acquisition in 2009 the development of the GigaMesh Software Framework began to visualize and extract cuneiform characters from 3D-models. It was used to process ca. 2.000 3D-digitized tablets of the Hilprecht Collection in Jena to create an Open Access benchmark dataset and an annotated collection of 3D-models of tablets freely available under CC BY licenses. Kasubi Tombs A 2009 CyArk 3D scanning project at Uganda's historic Kasubi Tombs, a UNESCO World Heritage Site, using a Leica HDS 4500, produced detailed architectural models of Muzibu Azaala Mpanga, the main building at the complex and tomb of the Kabakas (Kings) of Uganda.
A fire on March 16, 2010, burned down much of the Muzibu Azaala Mpanga structure, and reconstruction work is likely to lean heavily upon the dataset produced by the 3D scan mission. "Plastico di Roma antica" In 2005, Gabriele Guidi, et al. scanned the "Plastico di Roma antica", a model of Rome created in the last century. Neither the triangulation method, nor the time of flight method satisfied the requirements of this project because the item to be scanned was both large and contained small details. They found though, that a modulated light scanner was able to provide both the ability to scan an object the size of the model and the accuracy that was needed.
The modulated light scanner was supplemented by a triangulation scanner which was used to scan some parts of the model. Other projects The 3D Encounters Project at the Petrie Museum of Egyptian Archaeology aims to use 3D laser scanning to create a high quality 3D image library of artefacts and enable digital travelling exhibitions of fragile Egyptian artefacts, English Heritage has investigated the use of 3D laser scanning for a wide range of applications to gain archaeological and condition data, and the National Conservation Centre in Liverpool has also produced 3D laser scans on commission, including portable object and in situ scans of archaeological sites.
The Smithsonian Institution has a project called Smithsonian X 3D notable for the breadth of types of 3D objects they are attempting to scan. These include small objects such as insects and flowers, to human sized objects such as Amelia Earhart's Flight Suit to room sized objects such as the Gunboat Philadelphia to historic sites such as Liang Bua in Indonesia. Also of note the data from these scans is being made available to the public for free and downloadable in several data formats. Medical CAD/CAM 3D scanners are used to capture the 3D shape of a patient in orthotics and dentistry.
It gradually supplants tedious plaster cast. CAD/CAM software are then used to design and manufacture the orthosis, prosthesis or dental implants. Many Chairside dental CAD/CAM systems and Dental Laboratory CAD/CAM systems use 3D Scanner technologies to capture the 3D surface of a dental preparation (either in vivo or in vitro), in order to produce a restoration digitally using CAD software and ultimately produce the final restoration using a CAM technology (such as a CNC milling machine, or 3D printer). The chairside systems are designed to facilitate the 3D scanning of a preparation in vivo and produce the restoration (such as a Crown, Onlay, Inlay or Veneer).
Quality assurance and industrial metrology The digitalisation of real-world objects is of vital importance in various application domains. This method is especially applied in industrial quality assurance to measure the geometric dimension accuracy. Industrial processes such as assembly are complex, highly automated and typically based on CAD (Computer Aided Design) data. The problem is that the same degree of automation is also required for quality assurance. It is, for example, a very complex task to assemble a modern car, since it consists of many parts that must fit together at the very end of the production line. The optimal performance of this process is guaranteed by quality assurance systems.
Especially the geometry of the metal parts must be checked in order to assure that they have the correct dimensions, fit together and finally work reliably. Within highly automated processes, the resulting geometric measures are transferred to machines that manufacture the desired objects. Due to mechanical uncertainties and abrasions, the result may differ from its digital nominal. In order to automatically capture and evaluate these deviations, the manufactured part must be digitised as well. For this purpose, 3D scanners are applied to generate point samples from the object's surface which are finally compared against the nominal data. The process of comparing 3D data against a CAD model is referred to as CAD-Compare, and can be a useful technique for applications such as determining wear patterns on moulds and tooling, determining accuracy of final build, analysing gap and flush, or analysing highly complex sculpted surfaces.
At present, laser triangulation scanners, structured light and contact scanning are the predominant technologies employed for industrial purposes, with contact scanning remaining the slowest, but overall most accurate option. Nevertheless, 3D scanning technology offers distinct advantages compared to traditional touch probe measurements. White-light or laser scanners accurately digitize objects all around, capturing fine details and freeform surfaces without reference points or spray. The entire surface is covered at record speed without the risk of damaging the part. Graphic comparison charts illustrate geometric deviations of full object level, providing deeper insights into potential causes. Circumvention of shipping costs and international import/export tariffs 3D Scanning can be used in conjunction with 3D printing technology to virtually teleport certain object across distances without the need of shipping them and in some cases incurring import/export tariffs.
For example a plastic object can be 3d scanned in the United states, the files can be sent off to a 3d printing facility over in Germany where the object is replicated, effectively teleporting the object across the globe. In the future, as 3D scanning and 3D printing technologies become more and more prevalent, governments around the world will need to reconsider and rewrite trade agreements and international laws. See also 3D computer graphics software 3D printing 3D reconstruction 3D selfie Angle-sensitive pixel Depth map Digitization Epipolar geometry Full body scanner Light-field camera Photogrammetry Range imaging Structured-light 3D scanner Thingiverse References Category:Articles containing video clips
Pedestrian detection is an essential and significant task in any intelligent video surveillance system, as it provides the fundamental information for semantic understanding of the video footages. It has an obvious extension to automotive applications due to the potential for improving safety systems. Many car manufacturers (e.g. Volvo, Ford, GM, Nissan) offer this as an ADAS option in 2017. Challenges Various style of clothing in appearance Different possible articulations The presence of occluding accessories Frequent occlusion between pedestrians Existing approaches Despite the challenges, pedestrian detection still remains an active research area in computer vision in recent years. Numerous approaches have been proposed.
Holistic detection Detectors are trained to search for pedestrians in the video frame by scanning the whole frame. The detector would “fire” if the image features inside the local search window meet certain criteria. Some methods employ global features such as edge template , others uses local features like histogram of oriented gradients descriptors. The drawback of this approach is that the performance can be easily affected by background clutter and occlusions. Part-based detection Pedestrians are modeled as collections of parts. Part hypotheses are firstly generated by learning local features, which include edgelet and orientation features. These part hypotheses are then joined to form the best assembly of existing pedestrian hypotheses.
Though this approach is attractive, part detection itself is a difficult task. Implementation of this approach follows a standard procedure for processing the image data that consists of first creating a densely sampled image pyramid, computing features at each scale, performing classification at all possible locations, and finally performing non-maximal suppression to generate the final set of bounding boxes. Patch-based detection In 2005, Leibe et al. proposed an approach combining both the detection and segmentation with the name Implicit Shape Model (ISM). A codebook of local appearance is learned during the training process. In the detecting process, extracted local features are used to match against the codebook entries, and each match casts one vote for the pedestrian hypotheses.
Final detection results can be obtained by further refining those hypotheses. The advantage of this approach is only a small number of training images are required. Motion-based detection When the conditions permit (fixed camera, stationary lighting conditions, etc. ), background subtraction can help to detect pedestrians. Background subtraction classifies the pixels of video streams as either background, where no motion is detected, or foreground, where motion is detected. This procedure highlights the silhouettes (the connected components in the foreground) of every moving element in the scene, including people. An algorithm has been developed, at the university of Liège, to analyze the shape of these silhouettes in order to detect the humans.
Since the methods that consider the silhouette as a whole and perform a single classification are, in general, highly sensitive to shape defects, a part-based method splitting the silhouettes in a set of smaller regions has been proposed to decrease the influence of defects. To the contrary of other part-based approaches, these regions do not have any anatomical meaning. This algorithm has been extended to the detection of humans in 3D video streams. Detection using multiple cameras Fleuret et al. suggested a method for integrating multiple calibrated cameras for detecting multiple pedestrians. In this approach, The ground plane is partitioned into uniform, non-overlapping grid cells, typically with size of 25 by 25 (cm).
The detector produces a Probability Occupancy Map (POM), it provides an estimation of the probability of each grid cell to be occupied by a person. Given two to four synchronized video streams taken at eye level and from different angles, this method can effectively combine a generative model with dynamic programming to accurately follow up to six individuals across thousands of frames in spite of significant occlusions and lighting changes. It can also derive metrically accurate trajectories for each one of them. Related seminal work Histogram of oriented gradients Integral channel feature See also Human presence detection Human sensing References External links Code for POM – Pedestrian Detection from multiple cameras using Probabilistic Occupancy Map Pedestrian detection system for heavy equipment – Example of pedestrian detection system Blaxtair pedestrian detection system for mobile plant Category:Surveillance Category:Applications of computer vision
Lake Victoria supports Africa's largest inland fishery, with the majority of the catch being the invasive Nile perch, introduced in the Lake in the 1950s. History In 1927-1928 Michael Graham conducted the first ever systematic Fisheries Survey of Lake Victoria. The dominant species in the 1927/8 survey catches were two, now critically endangered tilapia species, the 'Ngege' or Singida tilapia (Oreochromis esculentus) and Victoria tilapia (O. variabilis). Other commonly observed species included: Marbled lungfish (Protopterus aethiopicus), Elephant-snout fish (Mormyrus kannume), Ripon barbel (Labeobarbus altianalis), African sharptooth catfish (Clarias gariepinus), silver butter catfish (Schilbe intermedius) and Semutundu (Bagrus docmak). The most common Haplochromis species were suggested to be Haplochromis guiarti and Haplochromis cinereus.
In his official report of the survey, Graham wrote that "The ngege or satu Tilapia esculenta, is the most important food fish of the lake, whether for native or non-native consumption. No other fish equals it in the quality of the flesh. It is convenient size for trade, travels well and is found in much greater numbers than other important fish, such as semutundu (Luganda), Bagrus sp.''''. Furthermore, Graham noted that the introduction of the European flax gill-net of 5 inch mesh had undoubtedly caused a diminution in the number of ngege in those parts of the Kavirondo Gulf, the northern shore of the lake, the Sesse Islands and Smith's Sound that were conveniently situated close to markets.
Before 1954, Lake Victoria's ecology was characterised by enormous biodiversity. It was inhabited by over 500 species of fish, 90% of which were cichlids belonging to the haplochromines. They are thought to have evolved in Lake Victoria within the last 15,000 years.Verheyen, Salzburger, Snoeks, and Meyer (2003). Origin of the Superflock of Cichlid Fishes from Lake Victoria, East Africa. Science 300: 325—329. They are known for their extraordinary ability to evolve rapidly to suit extremely localised and diverse environments, a characteristic termed 'evolutionary plasticity'. This ability has made the cichlid species of Lake Victoria an extremely successful fish. Haplochromine species accounted for some 80% of the fish biomass of the lake, an abundance which led Graham to believe that this species flock could support a trawler fishery of up to 200 boats.
It also meant that Lake Victoria at one time boasted one of the most diverse fish environments on earth. With such diversity, the cichlids of Lake Victoria managed to exploit virtually every food source available, including most detritus, zooplankton and phytoplankton. Haplochromine species are relatively small and bony, and were generally not favoured in catches. Riparian populations preferred the lake's two endemic species of tilapia (Oreochromis esculentus and O. variabilis). Hence, by the late 1940s, British colonial authorities were debating the overall ecological efficiency of the lake. For many authorities at this time, the lake needed a large and efficient predator to turn haplochromine fish stocks into something more economically valuable.
The prime candidate was the Nile perch (Lates niloticus). Arguments in favour of introducing a predator was as follows: Evidence from other African lakes suggested that the Nile perch could do well commercially, and if the fish were introduced into Lake Victoria, it would no doubt eat the haplochromines, and hence improve the overall value of the fishery. In addition, it was suggested that by introducing such a fish, fishers might turn their attentions to catching it, so easing some of the pressure on tilapia stocks. Because the Nile perch can weigh as much as , it was argued, fishers would be encouraged to use large mesh-sizes to capture it.
Furthermore, the perch was said to prefer off-shore habitats, and this would serve to relieve pressure on the in-shore tilapia fishery. In those lakes where the Nile perch was a native it co-existed with tilapia species, and therefore it posed no great danger to commercially important tilapia stocks in Lake Victoria. The potential size of the perch made it a fine sports fish, and this might attract sports fishers and tourists to the lake region. Finally, archaeological findings close to Lake Victoria suggested that an ancestor of the Nile perch had been native to the Miocene predecessor of Lake Victoria, Lake Karunga.
It was reasoned, then, that if the perch had once been native to the lake, there was little reason why it could not be a native again. The arguments against its introduction were as follows: Predators can never be as abundant as non-predators because of their nutritional requirements. In other words, the amount of fish a Nile perch has to eat to produce a kilogram of flesh is far greater than the amount of vegetative matter a tilapia has to eat to produce an equal amount of flesh. In ecological terms, the Nile perch is inefficient. As mentioned above, the fertility of tropical waters depends on the rate at which nutrients (mainly detritus) are brought back into solution.
The Nile perch, however, does not eat this detritus, and it was argued that its introduction would do little to improve the over-all ecological efficiency of the lake. If any fish should be introduced, it should be a herbivore or a detritivore. It would be wishful thinking to suppose that the Nile perch would exclusively consume haplochromines. Given the complexity of tropical ecosystems, it is impossible to predict what might happen should the Nile perch be introduced. While the argument continued, it was agreed that tilapia stocks needed bolstering largely as a result of increasing fishing pressure on indigenous species, associated with the expansion of the market for fresh fish in the 1940s.
Tilapia introductions started in the early 1950s with Oreochromis leucostictus from Entebbe, and followed by Tilapia zillii (Winam Gulf, 1953), T. rendalli (Winam Gulf 1953/54), O. niloticus (Kagera River 1954) and O. mossambicus (Entebbe 1961/62). Because tilapia are detritivores and herbivores, these introductions were regarded as less threatening than the introduction of any carnivore. Nevertheless, while the argument over the introduction of the Nile perch raged throughout the early 1960s, it seems that it had already been surreptitiously introduced in 1954 from Uganda. Once it had been discovered to be in the lake, further official introductions occurred in 1962 and 1963.
Introduced tilapia species were unable to establish themselves in the lake between the 1950s and 1963. Following unusually heavy rainfall in the early 1960s, however (the so-called 'Uhuru Rains'), the lake-level rose considerably, flooding large areas of shore-line, and opening up new breeding areas to fledgling tilapia stocks, so creating the opportunities for these exotic species to compete with indigenous stocks. Of the six exotic species introduced, two – Oreochromis niloticus and O. zillii – were to firmly establish themselves in the lake, so that by the early 1980s, these two species comprised the mainstay of tilapia catches. Of the indigenous species, O. esculentus was extirpated from the lake as a consequence of competition with introduced tilapiids, while O. variabilis populations declined significantly.
The Nile perch is a substantial predator. One specimen, preserved at the Kisumu Museum in Kenya, weighed when landed. Populations of the fish established themselves in a clockwise motion around the lake, starting in Uganda, followed by Kenya and ending in Tanzania. Initial catches were minimal, but grew rapidly in the 1980s, heralding the start of the so-called 'Nile perch boom'. "On the face of it...the lake after the debut of Lates [Nile perch] has turned into a fish producer that can only be described in Gargantuan terms". The introduction of the Nile perch had a decisive impact on haplochromine stocks which it favoured as its prey, affecting both their abundance and diversity.
It is believed that the contribution of this species flock to the fish biomass of the lake has decreased from 80% to less than 1% since the introduction of the Nile perch, and that some 40% of the haplochromine species were driven to extinction in the process.Lowe-McConnell, R. (2009). Fisheries and cichlid evolution in the African Great Lakes: progress and problems. Freshwater Reviews 2: 131-151. This may well represent the largest extinction event amongst vertebrates in the 20th century and has been called the "most dramatic example of human-caused extinctions within an ecosystem". Freed from their evolutionary predators, populations of the diminutive endemic silver cyprinid Rastrineobola argentea ( in Luo, in Ganda and in Swahili), flourished, developing into huge shoals.
In turn, pied kingfisher (Ceryle rudis) populations, that had hitherto fed on haplochromines, exploded in response to this new food source. Similar and other impacts have propagated throughout the ecosystem. Given its 'evolutionary plasticity', it follows that haplochromines should adapt rapidly to the new environmental conditions generated by the Nile perch 'boom' and eutrophic conditions. Evidence from studies on the lake does suggest that this is happening. One haplochromine, H. (Yssichromis) pyrrhocephalus, a zooplanktivore, was almost driven to extinction by the Nile perch. This species has recovered alongside increased exploitation of the Nile perch, at a time (the 1990s) when water clarity and dissolved oxygen levels had declined as a consequence of eutrophication.
Over a period of just two decades, H. pyrrhocephalus responded to raised hypoxia (oxygen deficiency) by increasing its gill surface area by 64%. Head length, eye length, and head volume decreased in size, whereas cheek depth increased. The former morphological changes may have occurred to accommodate this increased gill size. Other morphological changes suggest adaptations in response to the availability of larger and tougher prey types. By the end of the 1940s, fish stocks were under severe pressure. The market for fish grew since railways were available to carry fish to the coast and settlements in between. Improved fishing boats and nets were introduced.
British colonial authorities set out to remedy this through the introduction of exotic species, including tilapia and the Nile perch. These introductions had five main impacts. The first of these was the rise of the Nile perch. The fish took some time to establish itself, and only began to appear catch statistics in the mid-1970s. By the 1980s, the 'explosion' of this species was being referred to as the Nile perch 'boom'. Catches climbed from about 335 mt in 1975, to a peak of 380,776 mt in 1990. The second impact was the Nile perch's devastation of the haplochromine species flock, its main food source.
Catches of this species crashed. The third impact related to the lake's diminutive endemic silver cyprinid, the . Freed from competition (with haplochromine species) for food sources, this species thrived. It was not the main target of the Nile perch, and catches increased spectacularly from 13,000 mt in 1975, to an all-time high 567,268 mt in 2006. The fourth main impact of the introductions related to the exotic tilapia species. One of these, the Nile tilapia (Oreochromis niloticus), was to establish itself firmly in the fishery. Tilapia catches from the lake rose from about 13,000 mt in 1975, to an all-time high of around 105,000 mt in 2000.
There can be little doubt that these introductions saved the fishery from collapse. With such increases, so too the entire production system on the lake changed, the fifth and final key change. Prior to the arrival of the colonial administration, the fishery was dominated by fishermen (mainly, although certain fishing techniques were reserved for women) who owned their labour and their fishing gear. Contributing to the near-collapse of the fishery in the 1940s and 1950s was the reorganisation of the fishery into fleets drawing on hired labour and much improved gear. The Nile perch 'boom' was to accelerate and massively expand this process.
It coincided with an emerging European market for high-quality white fish meat, prompting the development of industrial fish processing capacity along the lake's shores in Kisumu, Musoma, Mwanza, Entebbe and Jinja. The export of Nile perch has since expanded away from the European Union (EU) to the Middle East, the United States and Australia, and now represents large foreign exchange earnings to the lake's riparian states. In Uganda, indeed, its export is second only to coffee in the rankings of export earnings. In 2006, the total value of Nile perch exports from the lake was estimated to be US$250 million.
The main market for the perch remains the EU, and the industry is, therefore, subject to the worries of EU health and safety inspectors. The EU has frequently closed its doors to the export for reasons ranging from unsatisfactory hygiene at factories to cholera outbreaks on the lake shores. Economic impact With such high demands for Nile perch, the value of the fishery has risen considerably. Labour inflows into the fishery have increased along with growing demand. In 1983, there were an estimated 12,041 boats on the lake. By 2004, there were 51,712, and 153,066 fishermen. The fishery also generates indirect employment for additional multitudes of fish processors, transporters, factory employees and others.
All along the lakeshore, 'boom towns' have developed in response to the demands of fishing crews with money to spend from a day's fishing. These towns resemble shanties, and have little in the way of services. Of the 1,433 landing sites identified in the 2004 frame survey, just 20% had communal lavatory facilities, 4% were served by electricity and 6% were served by a potable water supply. The impact of perch fishing on the local economy is the subject of the 2004 documentary Darwin's Nightmare. Controversy The Nile perch fishery has proved controversial, not least between conservationists keen to see the preservation of the lake's unique ecology; and others who recognise the fish's importance to regional economies and poverty alleviation.
In the 1990s, one group of thinkers argued that the export of this fish represented a net loss of fish proteins to riparian fishing communities, hence explaining high incidences of malnutrition amongst them. 'Empirical evidence ... vividly show that the growing export of the Nile perch and the commercialisation of the '' are undermining the survival of households'. Malnutrition amongst these communities are indeed high; one study estimates that 40.2% of children in fishing communities are stunted. Rates of childhood malnutrition are, however, lower around the lake than they were in the agricultural hinterland. At fish landing sites, 5.7% of mothers were found to be chronically malnourished.
The three countries bordering Lake Victoria – Uganda, Kenya and Tanzania – have agreed in principle to the idea of a tax on Nile perch exports, proceeds to be applied to various measures to benefit local communities and sustain the fishery. However, this tax has not been put into force, enforcement of fisheries and environmental laws generally are lax, and the Nile perch fishery remains in essence a mining operation so far. Notes References External links Lake Victoria Fisheries Organisation Kenya Marine and Fisheries Research Institute Tanzania Fisheries Research Institute Uganda National Fisheries Resources Research Institute Category:Lake Victoria * Lake Victoria
Pollyanna is a 1960 live action drama Walt Disney Productions feature film, starring child actress Hayley Mills, Jane Wyman, Karl Malden, and Richard Egan, in a story about a cheerful orphan changing the outlook of a small town. Based on the novel Pollyanna (1913) by Eleanor H. Porter, the film was written and directed by David Swift. The film won Hayley Mills an Academy Juvenile Award. It was the last film of actor Adolphe Menjou. Pollyanna was Hayley Mills' first film in the series of six for Disney. Plot Pollyanna, a 12-year-old orphaned daughter of missionaries, arrives in the small town of Harrington to live with her rich and strict aunt, Polly Harrington, in the 1900s.
Pollyanna is a very cheerful, talkative and radically optimistic youngster who focuses on the goodness of life and always finds something to be glad about, no matter the situation. In doing so, Pollyanna's positive outlook on everything results in her making a wide variety of friends in the community, including the hypochondriac and grouchy Mrs. Snow and the acidic recluse Mr. Pendergast. Aunt Polly's wealth controls most of the town. When the citizens want a derelict orphanage razed and rebuilt, Aunt Polly opposes the idea, arguing that her father donated the building to the town and, as such, it is an important landmark.
The townspeople defy her by planning a carnival to raise funds for a new structure. Because of the control Aunt Polly asserts over every facet of the town, however, many people feel reluctant to show their support. A group of citizens led by Dr. Edmond Chilton, Aunt Polly's ex-boyfriend, tries to persuade the town's minister, Rev. Ford, to publicly declare his support for the bazaar by reminding him that "nobody owns a church." Rev. Ford is reminded of the truth of that statement when Pollyanna delivers a note from Aunt Polly with recommendations to his sermon content. At church the following Sunday, having gained the gumption to defy Aunt Polly, Rev.
Ford first reads one of the so-called "Glad Passages" of the Bible stating that a young member of the congregation pointed out how many such passages there are. He intends to read one a week from now on, and then declares his support for the bazaar and encourages all to attend. Aunt Polly becomes furious about their audacity, forbidding Pollyanna to participate. On the evening of the carnival, Pollyanna is locked in her attic bedroom by Aunt Polly, but is "rescued" by playmate and fellow orphan Jimmy Bean, who reminds her that she will lead "America the Beautiful" at the high point of the event.
With Jimmy's help, she slips away and has a wonderful time at the carnival, winning a doll. Upon returning home, she avoids Aunt Polly by climbing a tree to her attic bedroom. When trying to reach her bedroom window, she drops her new doll; Pollyanna then falls out of the tree, screaming and is knocked unconscious before being discovered by Aunt Polly and her maids. After realizing her legs are paralyzed and that she may not walk again, Pollyanna develops severe depression, jeopardizing her chance of recovery. Meanwhile, Aunt Polly feels extreme guilt when she realizes how her behavior has isolated her from the town and Pollyanna.
While talking to Dr. Chilton, she admits that her niece needed love and it was something she never gave her. Dr. Chilton tells Aunt Polly that they can give Pollyanna the love together and help mend the isolation she put on the townsfolk. When the townspeople learn of Pollyanna's accident, they arrive at Aunt Polly's house with outpourings of love. Dr. Chilton carries the reluctant girl downstairs, where, one by one, the neighbors wish her health. Pollyanna's spirit gradually returns to its usual hopefulness and love of life, and she also learns that Jimmy has been adopted by Mr. Pendergast.
Pollyanna is embraced by her aunt before they leave Harrington with Dr. Chilton for an operation in Baltimore, which will correct her injury. Cast Hayley Mills as Pollyanna Whittier Jane Wyman as Polly Harrington, Pollyanna's aunt Kevin Corcoran as Jimmy Bean, an orphan who is eventually adopted by Mr. Pendergast Richard Egan as Dr. Edmond Chilton, Polly Harrington's ex-boyfriend Karl Malden as Reverend Ford, the church minister Agnes Moorehead as Mrs. Snow, a hypochondriac Jenny Egan as Mildred Snow, Mrs.
Snow's daughter Adolphe Menjou as Mr. Pendergast, a recluse who eventually opens his heart and adopts Jimmy Reta Shaw as Tillie Lagerlof, the cook Mary Grace Canfield as Angelica, the upstairs maid Nancy Olson as Nancy Furman, the downstairs maid and Pollyanna's new best friend James Drury as George Dodds, Nancy's boyfriend Leora Dana as Mrs. Ford, Reverend Ford's wife Gage Clarke as Mr. Murg, the town mortician Donald Crisp as Mayor Karl Warren, Dr. Chilton's uncle Edward Platt as Ben Tarbell, Amelia Tarbell's husband Anne Seymour as Amelia Tarbell Ian Wolfe as Mr. Neely Nolan Leary as Mr. Thomas Edgar Dearing as Mr. Gorman Director David Swift cameos as a fireman in an early scene.
Production notes Development The novel had been filmed before, notably with Mary Pickford in 1920 and by the late 1950s was still selling 35,000 copies a year. In June 1959 Disney announced he would make the film with Hayley Mills, Jane Wyman and Karl Malden, with David Swift to write and direct. Swift was best known at the time for his work in television. "It was the first time anyone would take a $2.5 million chance on me," he said. "Trust Disney to do it." Casting Disney cast Mills after seeing her in Tiger Bay. He watched this because he wanted to see the most recent performance by John Mills, who was going to be in Swiss Family Robinson for Disney; Hayley was also in the film, and Disney ended up offering her the lead in Pollyanna.
Her accent was explained by turning Pollyanna's parents into missionaries from the British West Indies. Disney said the cast was the most important in the studio's history, including names such as Wyman, Malden, and Richard Egan. "The cast scared me," said Swift. "Veterans of scores of movies, some of them. I was afraid they'd say 'TV man, go home'. But they didn't. It was a happy set; everybody worked his head off for me." Script Swift said in working on the script, in order to work against the "saccharine" nature of the material, he would spent a few hours every day first working on a horror play called The Deadly.
He would then work on Pollyanna. Swift said "in the book Pollyanna was so filled with happiness and light that I wanted to kick her. In the old days she came on like Betty Hutton. Now she is shy. We have an adult drag advice out of her." Swift also decided to remove a key plot point of the book, where Pollyanna was hit by a car and had to learn how to walk. He called this "too coincidental. Too pat." Swift added, "instead of making her the 'glad girl' of the book we've simmered her cheerfulness down to merely emphasize the things-could-be-worse attitude."
Shooting Filming started in August 1959. Pollyanna was filmed in Santa Rosa, California with the Mableton Mansion at 1015 McDonald Avenue in Santa Rosa serving as the exterior and grounds of Aunt Polly's house. Other California locations include Napa Valley and Petaluma. Interiors were filmed at the Walt Disney Studios in Burbank, California. Although the movie was filmed in California, in the book (written by Eleanor Porter) Harrington was set in Vermont. However, in the Disney movie, Harrington is located in Maryland as Baltimore is mentioned several times throughout the script. At the end of the film, Aunt Polly and Pollyanna take the train to Baltimore, probably headed to Johns Hopkins Hospital due to the delicacy of the operation needed.
(Johns Hopkins opened in 1889 and the story takes place in the 1900s.) Reception Box office In 1960, Disney reported that the film made a profit "but not nearly what we expected." Jerry Griswold of San Diego State University wrote in the New York Times of October 25, 1987: "An attempt was made to resuscitate Pollyanna in 1960 when Walt Disney released a movie based on the book. Time, Newsweek and other major reviewers agreed that such an enterprise promised to be a disaster – a tearjerker of a story presented by the master of schmaltz; what surprised the critics (their opinions were unanimous) was that it was his best live-action film ever.
But few had reckoned the curse of the book's by-then-saccharine reputation. When the movie failed to bring in half of the $6 million that was expected, Disney opined: 'I think the picture would have done better with a different title. Girls and women went to it, but men tended to stay away because it sounded sweet and sticky'". Awards and honors Hayley Mills won the 1960 Academy Juvenile Award for her performance, and also received a BAFTA nomination for Best Actress. The film is recognized by American Film Institute in these lists: 2006: AFI's 100 Years...100 Cheers – Nominated Merchandise The film generated a trickle of juvenile merchandise including a Dell comic book, a paper-doll collection, an LP recording, an illustrated Little Golden Book, and a 30" Uneeda character doll in a red and white gingham dress, pantaloons, and boots.
As part of a merchandise promotion, Disney was selling photo lockets with the quote claiming to be from Abraham Lincoln on them: "If you look for the bad in mankind expecting to find it, you surely will." Discovering the necklace in a gift shop while on vacation with his family, director/screenwriter David Swift called the studio to have the item recalled immediately, as it was not a quote from Lincoln, but actually a paraphrasing of a line from Eleanor Porter's original 1913 novel that was written for the film.
See also List of American films of 1960 Pretty Polly (film) References External links Category:1960 films Category:English-language films Category:1960s drama films Category:American films Category:American children's films Category:American comedy-drama films Category:Walt Disney Pictures films Category:Films based on American novels Category:Films based on children's books Category:Films directed by David Swift Category:Films produced by Walt Disney Category:Films about orphans Category:Films shot in California Category:Films set in the 1910s Category:Films set in 1912 Category:Films scored by Paul Smith (film and television composer) Category:Films adapted into comics Category:Films produced by Bill Anderson (producer) Category:1960 directorial debut films
Loud music is music that is played at a high volume, often to the point where it disturbs others and/or causes hearing damage. It may include music that is sung live with one or more voices, played with instruments, or broadcast with electronic media, such as radio, CD, or MP3 players. Playing loud music that can be heard from outside of the property from where it is being played (such as a house, apartment, hotel room, or motor vehicle) is considered to be rude by many people and societies. Among those opposed to the practice, it may result in the loss of respect and possible legal action.
But in certain contained settings, such as clubs or concerts, music is often played very loudly, but is viewed as acceptable. Consequences Criminal Many jurisdictions have laws defining loud music as a criminal offense, typically a misdemeanor. The exact definition of what constitutes a loud music violation varies by location, either at a certain volume (measured in decibels) or the distance from the source at which the music can be heard. The time of day is also often a factor in the law, with the restrictions in some places applying only to specified nighttime hours (e.g. 11 PM-7 AM). The amount of effort put forth by law enforcement members in dealing with loud music also varies by location.
The most common punishment for a conviction is a fine or some other small sanction. But on rare occasions, loud music may be grounds for imprisonment. In May 2008, a United Kingdom woman was sentenced to 90 days in jail for violating a court order not to play music that disturbed her neighbors eleven times. Police have also at times discovered other crimes, such as illegal drug usage, when investigating loud music complaints. Many public transportation services have rules against the use of sound-producing devices without earphones, or even with earphones if the music can be heard by others. Since mass transit agencies are frequently government-operated and/or subsidized, these rules can be legally enforced, and violation may result in prosecution.
In 2014, software engineer Michael Dunn was convicted of first-degree murder after fatally shooting 17-year-old Jordan Davis in an altercation over the loud music Davis was playing. Civil In many settings, loud music is not tolerated by property owners, and may be grounds for certain civil actions, such as eviction from rented property. Property owners at locations where patrons visit temporarily, such as hotels, campgrounds, or businesses, may order those who play loud music to leave the property. Health Continual exposure to loud music may result in hearing loss. The National Institute for Occupational Safety and Health (NIOSH) has developed a set of recommendations aimed at protecting the hearing health of musicians and those who work in music and entertainment venues.
Depending on the music sound levels and duration of exposure, as well as hearing protection used if any, the risk of hearing damage can vary significantly. Music played at 85 decibels, or level of sounds, for prolonged periods of times can cause hearing damage, for instance, sound levels at some rock concerts can reach 110-120 A-weighted decibels, and at those levels, the maximum daily limit set by most standards and regulations can be reached in less than one minute of exposure. Continual exposure to loud music can also lead to tinnitus. It is predicted that exposure to loud music will cause as many as 50 million Americans to suffer hearing loss by 2050.
Excessive drinking A study conducted by French scientists showed that loud music leads to more alcohol consumption in less time. For three Saturday evenings researchers observed customers of two bars situated in a medium-sized city in the west of France. Participants included forty males aged between 18 and 25, who were unaware that they were subjects of a research. The study featured only those who ordered a glass of draft beer (25 cl. or 8 oz.). The lead researcher, Nicolas Guéguen, said that each year more than 70,000 people in France die from an increased level of alcohol consumption, which also leads to fatal car accidents.
See also Earmuff Earplug Hearing impairment Loudest band in the world Music torture Noise induced hearing loss Noise regulation Sound Sound power level Soundproofing Tinnitus References Category:Anti-social behaviour Music Category:Psychological torture techniques
Optic nerve sheath meningiomas (ONSM) are rare benign tumors of the optic nerve. 60–70% of cases occur in middle age females, and is more common in older adults (mean age 44.7 years). It is also seen in children, but this is rare. The tumors grow from cells that surround the optic nerve, and as the tumor grows, it compresses the optic nerve. This causes loss of vision in the affected eye. Rarely, it may affect both eyes at the same time. It is typically a slow growing tumor, and has never been reported to cause death. However, there is concern that the tumor can grow into the brain and cause other types of neurological damage.
In some patients, the tumor grows so slowly that treatment is not necessary. Standard treatments are observation, surgery, radiation therapy, and combinations of the above. Symptoms The most common symptom of ONSM is a gradual loss of vision in one eye. In a minority of patients this may be intermittent, at least to begin with. Less common symptoms include pain in the affected eye, protrusion of the eye, or double vision. Natural history ONSM does not improve without treatment. In many cases, there is gradual progression until vision is lost in the affected eye. However, this takes at least several months to occur, and a minority of patients remain stable for a number of years.
Diagnosis Clinical examination will show an abnormal optic disc, either swollen or atrophic. Optociliary shunt vessels may be seen; the combination of these with progressive visual loss and optic disc atrophy is known as the Hoyt-Spencer triad. Visual acuity is usually but not always reduced. When ONSM is suspected, MRI of the brain or orbits should be performed. This will usually show characteristic findings and confirm the diagnosis. Treatment Most ophthalmologists will not advocate any treatment unless visual loss is present and ongoing. Reports of patients with ONSM having no change in their vision for multiple years are not uncommon.
If loss of vision occurs, radiation therapy will improve vision in about ⅓ of cases, and preserve vision in about ⅓ of cases. Surgery has traditionally been associated with rapid deteroriation of vision. However, newer surgical techniques may prove better for the treatment of ONSM. Incidence About 1–2% of all meningiomas are optic nerve sheath meningiomas. Meningiomas have an incidence of ~4.18/100,000 persons each year. Thus, ~10,000 meningiomas are diagnosed in the US each year; corresponding to ~100 cases of ONSM each year in the US. The actual number of meningiomas is likely much higher as it is very common in elderly women.
ONSM comprises about 2% of orbital tumors, and about 10% of optic nerve lesions. Neurofibromatosis type II (NF-2) affects around 9% of ONSM patients, where the incidence in the general population is around 0.03–0.05%. Thus NF-2 is felt to be a risk factor for the development of ONSM. References Category:Ocular neoplasia Category:Brain tumor
The ArcelorMittal Orbit (often referred to as the Orbit Tower or its original name, Orbit) is a 114.5-metre-high sculpture and observation tower in the Queen Elizabeth Olympic Park in Stratford, London. It is Britain's largest piece of public art, and is intended to be a permanent lasting legacy of London's hosting of the 2012 Summer Olympic and Paralympic Games, assisting in the post-Olympics regeneration of the Stratford area. Sited between the Olympic Stadium and the Aquatics Centre, it allows visitors to view the whole Olympic Park from two observation platforms. Orbit was designed by Turner-Prize winning artist Sir Anish Kapoor and Cecil Balmond of Arup Group, an engineering firm.