The thickness baker is very similar to the ambient occlusion baker, but it casts the rays in the opposite direction of the surface normal. (So it's as if you were baking an AO with the normal inverted).
- The black values represent the thin parts of the model.
- The white values represent the thick parts of the model.
It can be used in a Sub Surface Scattering (SSS) shader or directly in the diffuse/albedo to fake a SSS effect.
Secondary Rays: amount of secondary rays (the higher will produce less noise)
Min Occluder Distance: minimum distance where the secondary rays will hit the high poly geometry
Max Occluder Distance: maximum distance where the secondary rays will hit the high poly geometry
Relative to Bounding Box:
- off: units used in "Max Frontal Distance" et "Max Rear Distance" are the ones defined when exporting your mesh (m, cm or whatever you did set up in your scene export)
- on: units are relative to the bounding box of the object, 1.0 being the diagonal length of the bounding box
Spread Angle: maximum spread angle of occlusion rays.
Distribution: angular distribution of occlusion rays.
Ignore Backface: defines if the rays should ignore hits on a backface (if the high poly normal faces the opposite direction as the low poly from where the ray is fired). You should want this option activated most of the time.
Automatic Normalization: defines if the thickness map should be auto-leveled to make sure the brightest point is set to pure white and the darkest point is set to pure black.