This page describes the use of shadow maps on Max lights within V-Ray.
The VRayShadowMap plugin can be used to achieve mapped shadows with standard 3ds Max lights and V-Ray. It will cast correct shadows from all V-Ray geometric objects, including Proxy Objects | VRayProxy, Procedural Fur | VRayFur, and objects with V-Ray displacement. The VRayShadowMap can be useful to avoid flickering on objects like VRayFur in cases where true area shadows are too slow to calculate. Note that the actual shadows are still calculated with ray tracing, but the results are cached in a rectangular shadow buffer that is used to speed up the calculations.
UI Path: ||Create a standard 3ds Max light|| > Modify panel > General Parameters rollout > choose VRayShadowMap from dropdown
mode – Controls the calculation mode for the shadow map when rendering animations:
Single frame – Calculates a new shadow map at each frame of an animation.
Fly-through – Reuses the same shadow map at each frame of the animation. This option is only suitable for static fly-through scenes, where the only moving object is the camera.
resolution – Determines the resolution of the shadow map. Lower values will lead to faster rendering times and less RAM usage, but the shadows may be blocky and not very precise. Higher values increase the shadow quality, but take more RAM and time to calculate.
bias – V-Ray can compute the shadows at a point that is slightly displaced above the actual surface being shaded. This may be useful to prevent "surface acne" (black spots on the surface because of incorrect self-shadowing).
filter – Specifies the size of the filter used to reconstruct shadows from the shadow map. Larger values blur the shadows and may help to reduce flickering or blocky artifacts, but may be slower to calculate.
filter method – Determines the way in which the shadow reconstruction filter is calculated:
Exact – Produces smooth results but may be slow to calculate, particularly for large Filter values.
Fast – Calculates an approximate filter; this is faster than the Exact option for large Filter values, but may introduce noise in the rendering depending on the Filter subdivs value.
filter subdivs – When the filter method is set to Fast, this determines the number of samples that will be used to calculate the shadow filter. Lower values render faster, but may introduce noise in the rendering.