Scatter To

Object "Scatter To" method is set in the Scatter To section of the Object Properties window. The Object Properties can be reached by clicking the down arrow in the Object Properties bar above the NSC Editor.

A very large number of rays may need to be traced to find a relatively small number of scattered rays that strike an object of interest, such as a detector. There are two ways to improve the efficiency of the scattering analysis.

The first method is to scatter a ray according to the scatter distribution, but only trace the ray if the ray propagates towards an object of interest. This method may be implemented by defining a "Scatter To" list of objects. The Scatter To method works well for wide angle scatter (such as Lambertian scatter) and when the object of interest subtends a relatively large angle as seen from the scattering surface.

The second method is to always scatter the ray towards the object of interest, and then to normalize the energy the ray carries to account for the probability the ray would have actually scattered in that direction. This method is called "Importance Sampling". Importance Sampling is generally superior to the Scatter To method if the scatter is narrow angle or the object of interest subtends a relatively small angle as seen from the scattering surface.

Next:

• The Scatter To List
• Importance Sampling