We compare a creased displaced catmull-clark subdivision surface with an equivalent polygon mesh.
Increasing the micropolygon length is equivalent to making the object's size smaller in the image. At 512, it is what RenderMan renders when this object fits into a single pixel !
- When the object is large, it is finely tesselated into milions of micropolygons, showing fine displacement detail.
- When the object becomes smaller than a pixel, only the base mesh remains.
Micropolygon Length works a bit like an "automatic level of detail" and preserves memory when an object is so small in screen that it doesn't need an fully detailed representation.
Notice that the subdiv degrades to a much lower number of faces, preserving memory and speeding up raytracing.
This is what we call Data Amplification, when a compact geometric representation can be augmented to create more detail on demand.