ray casting


ray casting

(graphics)A simplified form of ray tracing. A ray is firedfrom each pixel in the view plane, and information isaccumulated from all the voxels in the volume data itintersects.

Each voxel is first given an associated colour and opacity.The ray is sampled at a fixed number of evenly spacedlocations and the colour and opacity are trilinearlyinterpolated from the eight nearest voxels. These are thencomposed linearly back to front to give a single colour forthe pixel.

Ray casting was invented by John Carmack for the gameWolfenstein 3D. It is faster and lower quality than raytracing, and is ideal for interactive applications. Itparallelises well, although random access is needed to thevoxels.