Ray tracing in 3D graphics




Bishop, Robert B.

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The purpose of the study is to analyze the properties and functions of ray tracing, and to describe realistic 3D graphics applications. Ray tracing can be described as a global illumination based rendering method. Rays of light trace from the eye back through the image plane into the scene. Then the rays are tested against all objects in the scene. The basic algorithm goes back to 1968, when Appel was attempting to solve the hidden surface problem when rendering 3D objects. The algorithm works in object space, where we visualize a point in the image plane and trace into the scene with color and intensity from that point. In 1637, René Descartes wrote a treatise, describing his experiments and observations, to explain the shape of the rainbow. Recursive ray tracing, the difficulties of geometrical calculation and the long run-times of early work are discussed. Ray tracing geometry can create a situation where rays spawn more rays. Direct illumination and global illumination are presented with examples. Shadows are created when objects interrupt the light source vector with an additional ray created, called the “shadow feeler.” There are difficulties in the reflection-illumination model, in aliasing, sharp shadows and signature problems. This is investigated as distributed ray tracing. Ray tracing and anti-aliasing are discussed, along with potential improvements. Recent references provide new techniques with promise for future systems, such as interpolation, video textures and a psychophysically-based light reflection model.



Applied sciences, Pure sciences, Recursive ray tracing