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Topic: Ray tracing


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  Ray tracing
Ray tracing's popularity stems from its realism over other rendering methods (such as scanline algorithms); effects such as reflections and shadows, which are difficult to simulate in other algorithms, follow naturally from the ray tracing algorithm.
The main drawback of ray tracing is that it can be an extremely slow process, due mainly to the large numbers of light rays which need to be traced, and the larger number of potentially complicated intersection calculations between light rays and geometry (the result of which may lead to the creation of new rays).
Ray tracing has also shown itself to be very versatile, and in the last decade ray tracing has been extended to global illumination rendering methods such as photon mapping and Metropolis light transport.
www.ebroadcast.com.au /lookup/encyclopedia/ra/Ray_tracing.html   (522 words)

  
 The Recursive Ray Tracing Algorithm
Ray tracing is a method of generating realistic images by computer, in which the paths of individual rays of light are followed from the viewer to their points of origin.
Ray casting is a method in which the visible surfaces of objects (those parts of the scene that are immediately visible to the camera) are found by throwing (or casting) rays of light from the viewer into the scene.
Because the standard ray tracing algorithm actually follows the path of light from the eye of the viewer backward to the light source, it is, in that sense, often referred to as backward ray tracing.
www.geocities.com /jamisbuck/raytracing.html   (4225 words)

  
 Volume Graphics - Discrete Ray Tracing   (Site not responding. Last check: 2007-10-13)
Ray tracing [2] is an image generation technique that simulates light behavior in a scene by following sight rays from the observer's eye as they interact with the scene and the light sources.
Unlike conventional ray tracing algorithms, in which analytical rays are intersected with the object list in order to find the closest intersection, in RRT 3D discrete rays (which are essentially voxelized lines) are traversed through the 3D raster in order to find the first surface voxel.
In conventional ray tracing, computation time grows with the number of objects, and performance is greatly influenced by the type of objects comprising the scene; intersection calculation between a ray and a parametric surface is significantly more complex than intersecting the ray with a sphere or a polygon.
www.cs.sunysb.edu /~vislab/projects/volume/Papers/Discrete.html   (917 words)

  
 Ray Tracing
Ray tracing provides several basic features that are unavailable in a standard scanline renderer: accurate reflections, refractions, and soft shadows.
If the ray hits this sphere as well, we are forced to construct the actual static triangle at the ray's moment, by spline-interpolating the positions of its vertices.
By distributing the rays evenly over space and time, using a jittering approach that evenly spreads out the samples while adding a modicum of random noise to reduce aliasing, we are able to achieve high quality motion blur with our ray tracer.
www.rhythm.com /~ivan/ray.html   (1330 words)

  
 Category:Ray Tracing - DmWiki
Ray tracing is a very elegant algorithm to synthesize an image from a geometric scene description.
For that reason the name ray tracing is often synonymously used to describe a certain class of rendering algorithms that are based on the original method (which is often called classic or Whitted ray tracing).
In contrast to ray tracing or rasterizing these algorithms are concerned only with that one problem which, central as it may be, does not entirely solve what rendering tries to accomplish.
www.devmaster.net /wiki/Category:Ray_Tracing   (624 words)

  
 Ray Tracing: Graphics for the Masses
The two rays will be identical, except for their direction: if the original ray came directly from the light source, then the backwards ray will go directly to the light source; if the original bounced off a table first, the backwards ray will also bounce off the table.
The final color of the ray (and therefore of the corresponding pixel) is given by the colors of the objects hit by the ray as it travels through the scene.
If a ray intersects an object, the object's intersection routine returns the distance of the intersection point from the origin of the ray, the normal vector at the point of intersection, and, if texture mapping is being used, a coordinate mapping between the intersection point and the texture image (discussed later in Texture Mapping).
www.acm.org /crossroads/xrds3-4/raytracing.html   (3861 words)

  
 Ray tracing - Wikipedia, the free encyclopedia
Ray tracing is a general technique from geometrical optics of modelling the path taken by light by following rays of light as they interact with optical surfaces.
Ray tracing describes a method for producing visual images constructed in 3D computer graphics environments, with more realism than either ray casting or scanline rendering techniques.
The first ray casting (versus ray tracing) algorithm used for rendering was presented by Arthur Appel in 1968.
en.wikipedia.org /wiki/Ray_tracer   (2759 words)

  
 Ray tracing - Uncyclopedia
Things were very different back in the ancient Rome where ray tracing was viewed as one of the highest goals of mankind.
Ray tracing was practiced in this form for centuries to come and people were generally happy, until the reneissance came and suddenly everyone realized that ray tracing was all gay.
The infidels still thinking ray tracing as cool were hunt down and drowned into guinea pigs or something.
uncyclopedia.org /wiki/Ray_tracing   (502 words)

  
 GRACE++ - Ray Tracing Introduction
After pointing out the advantages of ray tracing over current z-buffering technologies, a rough estimation of the processing requirements of real-time ray tracing is given.
The difference between the current methods and ray tracing is the ability to calculate the graphical models of shadows, reflections and refraction, whereas current rendering engines only try to simulate these effects by painting shadow pictures or reflection pictures (so called textures) onto objects.
The influence of all secondary rays are superposed.
www.ert.rwth-aachen.de /Projekte/grace/raytracing.html   (576 words)

  
 Ray Tracing in C# and .NET   (Site not responding. Last check: 2007-10-13)
The sphere is the simplest object to ray trace, because the sphere can be described in one simple formula, where other shapes such as a cube need to be described as the combination of several planes.
For the nearest intersection with the solid object, determine a shade corresponding to the distance of the ray to the object.
Ray tracing is a very powerful demonstration of what a computer is capable of graphically purely through mathematics.
www.c-sharpcorner.com /code/2002/oct/RayTracing.asp   (1502 words)

  
 Ray Tracing   (Site not responding. Last check: 2007-10-13)
Ray tracing is especially useful for rendering images which contain reflective surfaces and transparent or translucent objects.
Lines, or rays, are projected from the observer's viewpoint through the "camera" or window through which the 3D scene is viewed, one ray for each pixel in the window.
At each stage, the colour of the object that the ray strikes is noted and the eventual result is a colour value which is plotted to the relevant screen pixel.
www.meko.co.uk /raytracing.shtml   (410 words)

  
 Thin Lens Ray Tracing Program
Rays are then drawn one segment at a time, waiting for a key press to continue.
As you change the object height, you are magnifying the paraxial ray situation in the vertical direction, and rays "refract" at the lens plane.
The ray through the center is drawn first, then the incident parallel ray, and finally the incident ray which (if extended) passes through the appropriate focal point.
www.lhup.edu /~dsimanek/scenario/raytrace.htm   (3672 words)

  
 Ray Tracing Overview
Ray tracing is a method of rendering a visual scene by tracing simulated rays of light in reverse from a camera or eye location, through each pixel of a user-defined image plane, into a three-dimensional scene (also user-defined), and then back to the originating light source.
Because ray tracing is an estimation of processes occurring in nature, resulting images appear very photorealistic.
This is done by substituting the ray equation into the object equation (for a simple case) and solving the resulting quadratic equation for real values of 't'.
www-viz.tamu.edu /students/jaf/viz616/ray.htm   (1309 words)

  
 Ray Tracing Images by Henrik Wann Jensen
Ray tracing is particularly good at simulating sharp shadows, mirrors and glass while other effects such as caustics and colour bleeding are neglected.
An advantage of ray tracing based rendering approaches compared to radiosity is that they handle procedural models and complex objects that do not need tessellation.
This is a 3D ray traced rendering of a 4D Julia fractal (evaluated as the standard 2D version except this one uses 4D quaternions).
graphics.ucsd.edu /~henrik/images/raytrace.html   (340 words)

  
 Ray tracing primitives
To intersect a ray with this, substitute Equation 24 in Equation 36.
To intersect a ray with this, substitute Equation 24 in Equation 47.
In order to ray trace one of these primitives in an arbitrary location we have two alternatives: (1) find general intersection algorithms between a ray and the arbitrarily located versions of the primitives; or (2) use geometric transforms to scale, rotate, and translate these primitives into the desired locations.
www.cl.cam.ac.uk /Teaching/1999/AGraphHCI/SMAG/node2.html   (2111 words)

  
 Ray Tracing
For a rectangular plate of glass the emerging ray travels a path parallel to the incident ray, but for glass curved inward (concave) or out ward (convex) rays are either diverged (spread out) by concave lens or converged (focused to a point) by a convex lens.
The ray tracing apparatus will produce a single beam or a series of parallel rays which will be affected by the mirrors or lenses placed in their paths.
If a ray inside an optical device is incident on the exit surface at some angle C beyond that which is limited by the sine function, the ray will be completely reflected off the surface better than any mirror could reflect it.
www.ccphysics.us /henriques/PS112/raytrace1.htm   (766 words)

  
 2A) Ray tracing primitives
We can thus write a routine to intersect an arbitrary ray with an axis-aligned box and then transform the ray under consideration in exactly the same way as we transform the box which we are trying to intersect with it.
This is achieved by intersecting the ray with the appropriate infinitely long cylinder and then ascertaining where along the cylinder the intersection lies.
The disc is not a common ray tracing primitive, but is necessary in ray tracers which implement cones and cylinders without end caps.
www.cl.cam.ac.uk /Teaching/2000/AGraphHCI/AG/p2a.html   (1039 words)

  
 Introduction to Ray Tracing
Ray tracing is a very popular rendering technique, which consists of studying the path taken by light by following rays of light as they interact with optical surfaces.
For each ray that is casted into the scene, it is followed through the entire scene until it's either shone into infinite and empty space, or it hits a light source.
If however, the ray hits a light source, then the path that the ray has taken, in addition to the light source that it hits will all be used to calculate what colour that rays corresponding pixel will be.
www.expertsrt.com /articles/Darkins/RayTracing.shtml   (918 words)

  
 An introduction to ray tracing
Ray tracing is perhaps one of the most straightforward ways to get a computer to model our 3-D world on a 2-D monitor.
Ray tracing is quite possibly the most used technique in film and television to achieve computer special effects, because it is so precise.
These rays hit the back of the eye, the retina, which is equipped to detect the photons hitting it.
www.mit.edu /~danz/marti/intro.html   (1929 words)

  
 [No title]
What puts ray tracing out of reach for most rendering applications is the sheer amount of processing power that it takes to determine the correct behavior of the billions of beams of light that can illuminate a large, complex scene.
The Intel paper isn't focused on real-time ray tracing, and the numbers in the paper show it to be just beyond the reach of desktop processors at the time of publication (2005).
Because ray tracing's performance scales so well with the the number of threads of execution, I think that Scientific American is right when they claim that we're on the cusp of a new wave of major graphics improvements.
arstechnica.com /news.ars/post/20060805-7430.html   (929 words)

  
 Vulnerability / Survivability Ray-Tracing Tool
Modern vulnerability and survivability codes simulate the path of threat projectiles through a target using a technique known as "ray tracing." Rays, also known as shotlines, are described mathematically by an origin, a direction, and a length.
Rays are "traced" by finding intersections between the ray and the target geometry as the length of the ray is increased from zero.
In addition to finding efficient algorithms for intersecting rays with surfaces and solids, much of the science of ray tracing has focused on reducing the number of ray-geometry intersections that must be examined.
www.thermoanalytics.com /products/muses/survivability.html   (2164 words)

  
 Interactive Ray Tracing Project   (Site not responding. Last check: 2007-10-13)
This project, done in collaboration with the sci group, explores of an interactive ray tracing system designed for current multiprocessor machines.
The ray tracing system is interactive in part because it runs on a high-end machine (SGI Origin 2000) with fast frame buffer, CPU set, and interconnect.
ray tracing allows a wide range of primitives and user programmable shading effects.
www.cs.utah.edu /vissim/projects/raytracing   (290 words)

  
 Ray Tracing Example   (Site not responding. Last check: 2007-10-13)
While the ray tracing web application can serve multiple users at once (notwithstanding that the application is limited by its heavy CPU load), one can also imagine that the web interface is intended for use by a single user on the local machine.
Once the defsys.lisp file is loaded into lisp the basic ray tracing application can be compiled (or recompiled) by executing the form (excl:compile-system :ray-trace) and then executing the form (excl:load-system :ray-trace) to ensure that the current compiled files have all been loaded.
The ray tracing algorithm would be modified so that instead of finding the closest intersection of each a ray with any object, each ray trace would collect all intersections.
www.dynamiclearningcenter.com /samples/ray-tracing/description.html   (3185 words)

  
 What is ray tracing? - A Word Definition From the Webopedia Computer Dictionary
Ray tracing software works by simulating the path of a single light ray as it would be absorbed or reflected by various objects in the image.
To work properly, the artist must specify parameters of the light source (intensity, color, etc.) as well as all the objects (how reflective or absorbent the materials are).
Ray tracing requires enormous computational resources, and is supported by only the most advanced graphics systems.
www.webopedia.com /TERM/R/ray_tracing.html   (188 words)

  
 Ray Tracing
It's called ray tracing because the method used is for the computer to project a ray into the scene from each pixel in the image area.
The ray is traced back through all the reflections to identify the locations of all the shadows, highlights, etc.
A ray tracing seemed just the ticket since it allows total control and some degree of simplification, making for a better graphic.
webpages.charter.net /wb8rcr/raytrace.html   (506 words)

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