The Ray Tree

When ray tracing a scene, reflected or transmitted rays may strike other reflective or transparent objects. Further reflected or transmitted rays will be spawned, and so on. Taken together, such a family of rays is termed the <#202#>ray tree<#202#>. Care must be taken to control the depth of this tree: If it is allowed to grow too deeply, one may spend a great deal of time computing rays that contribute little to the final picture; if it is not allowed to grow far enough, this premature tree pruning may be evident in the image.

<#203#><#1791#>Rayshade<#1791#><#203#> provides two complementary methods for controlling the depth of the ray tree. One method sets an absolute maximum for the tree. The other allows one to adaptively prune a tree as it grows so that ``unimportant'' rays are not spawned.

<#4635#><#4635#>

<#1194#>maxdepth<#1194#> <#1195#>level<#1195#>
Do not spawn rays deeper than those at the given <#207#>level<#207#>.

<#4636#><#4636#>

<#1198#>cutoff<#1198#> <#1199#>threshold<#1199#>
Do not spawn rays whose contribution to the final color of the eye ray is less than <#214#>threshold<#214#> for each color channel. Threshold may be given as a single floating-point value, or as a red-green-blue triple.