| OCR Text |
Show 3 remain with the Catmull algorithm are that the computation time goes up roughly as the square of the resolution, and that the application of anti-aliasing techniques, for the surpression of some of the effects of sampling, is not straightforward. These problems are addressed by a new algorithm which generates the picture elements in the more conventional scan line (left to right, top to bottom) order. When a particular picture element is generated all information about what is visible near that element is available in the same place at the same time. This is a condition required for convenient application of anti-aliasing techniques. Computation time is reduced by requiring calculation at only a few visually important points along a scan line, and by interpolating intensities between them. The descr.iption of this algorithm is preceeded by Chapters 2,3, and 4 which lay the mathematical background necessary to understand the algorithm in Chapter 5. Surface Property Simulation Once the geometrical calculations have been performed, the second stage of picture synthesis, the calculation of intensities for the visible surfaces must be done. This process is essentially a simulation of light reflecting'off the surface. The view taken here divides this process into two categories: simulation of the micro-structure of the surface and simulation of the macro-structure. |
