2008

■ Large BSP. This method can perform better with large scenes and with
distributed bucket rendering.
You set the raytrace acceleration method on the Render Scene Dialog >
Renderer panel >
Rendering Algorithms rollout on page 6118 .
Ray-Trace Bias
On the right, increased map bias makes the dog appear to float.
A single parameter, Ray-Trace Bias, affects the generation of
ray-traced shadows
on page 7907 . You set this parameter in the Shadow Parameters rollout.
The Ray-Traced bias control in the Shadow Parameters rollout moves the
shadow toward or away from the shadow-casting object (or objects). By default,
this value is 1 unit.
Increasing the bias moves the shadow away from the object, and decreasing
the bias moves the shadow closer to the object. The Ray-Trace Bias value can
be any positive floating-point number.
For example, if a shadow-casting object intersects another object but its shadow
doesn't meet properly at the intersection, the bias is too high. This effect varies
with the angle of the spotlight to the object. Extremely shallow spotlight
angles usually require higher bias values.
Another purpose of bias is to avoid problems with objects that cast shadows
onto themselves. If you see streaks or moiré patterns on the surface of the
object, the bias value is too low.
7906 | Glossary