Our treatment of patterns and textures was inspired by Perlin's flexible shading language [17], to which we have added the mapping of lookup functions for multi-dimensional data. Using this technique, it is possible to interpret tabulated or image data in any manner desired through the same functional language used for procedural patterns and textures.
Figure 12 shows a scene with many patterns and textures. The textures on the vases and oranges and lemons are procedural, as is the pattern on the bowl. The pattern on the table is scanned, and the picture on the wall is obviously an earlier rendering. Other patterns which are less obvious in this scene are the ones applied to the three light sources, which define their output distributions. The geometry was created with the generator programs included with Radiance, which take functional specifications in the same language as the procedural patterns and textures. The star patterns are generated using a Radiance filter option that uses the pixel magnitude in deciding how much to spread the image, showing one advantage of using a floating-point picture format [27]. (The main advantage of this format is the ability to adjust exposure after rendering, taking full advantage of tone mapping operators and display calibration [23][30].)
