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Render Engine

Select the render engine used for primary rays. This can be either REYES or the path tracer. For interactive re-rendering only the path tracer will work (REYES will re-parse the entire scene at each render).

Progressive

Shading Rate

When using the REYES render engine, the shading rate is a fundamental quality control parameter and formally speaking, it defines the rate (or frequency) at which a surface is shaded. From The RenderMan Companion, page 214: " ... [The Shading Rate] controls the frequency of shading a surface. size is specified as an area in pixels: if size is 1, a surface is shaded about once per pixel. Large values of size cause cruder but faster shading. "

In 3Delight, the shading rate actually controls how finely surfaces are tessellated. Since the shading rate is specified in "area of pixels", micro-polygon renderers simply tessellate surfaces so that each micro-polygon is of the specified area. And since every micro-polygon is an atomic unit of shading , we automatically obtain the desired shading rate. There is an important implication to this:

Higher shading rates (such as 20) not only make objects look blurrier (less frequent shading), but also make surface silhouettes look less smooth. This is because the shading rate and the tessellation are interconnected in a micro-polygon based renderer.

Note however that shading rate has absolutely no effect on edge anti-aliasing, which is controlled through the filtering parameters described next.

In practice, the following shading rate values are common: