Autodesk AUTOCAD 2006 Command Reference Manual page 1044

Maximum Depth
Defines the depth of the tree used by the Photo Raytrace renderer to track
reflected and refracted (transmitted) rays. The default value is 3. Greater
values give more accuracy but increase rendering time—it is recommended
that you not use a maximum depth greater than 10.
Medium
Renders with analytical horizontal anti-aliasing and nine multiple shading
samples per pixel. The more samples per pixel, the more time it takes to
render the image.
Minimal
Renders with analytical horizontal anti-aliasing only.
Minimum Bias
Sets the lowest value in the range. The default is 2.0. The valid range of
values depends on the scene to render, but it should usually be between
2.0 and 20.0.
Mip Map Sample
Averages bitmap pixels using the mip method—a pyramidal average based
on square sample areas.
Point Sample
Selects the nearest pixel within the bitmap.
Adaptive Sampling
Accelerates the anti-aliasing process within the bounds of the sample matrix
size. Given a contrast threshold that you supply, the program judges whether
it can process fewer samples than specified for the matrix and still get adequate
results.
Ray Tree Depth
Controls the ray tree.
Face Controls
Controls how RENDER treats the faces of 3D solid objects.
Depth Map Shadow Controls
Adjusts the shadow map bias, which moves a shadow relative to the
shadow-casting object to prevent self-shadowing or detached shadows.
1020 | Chapter 19