Render mask is really invaluable to update images for material, lighting changes etc it would be very useful to have a feature to expand the selected mask in pixels to allow for those occasions when the geometry has also changed.
I don’t get it. Can you explain an actual use case and what in that use case VRay would do exactly?
Okay say your rendering an kitchen interior and the client has asked you to replace all of the cupboard handles and they have now changed from a small round knob to something larger.
Using the selected mask you render the handle but miss the shadow because its beyond the size of the new geometry this is where expanding the mask would help saving time on having to render lots of regions or re-rendering the whole image.
Phew. Okay I see what you intend to do. Depends on the actual effort needed on the coding side, since this is an issue easily solved by doing the same in photoshop.