Hi,
When rendering shadow on a shadow catcher material Im getting some blotchy shadows, the scene is using a dome light with hdri.
Also the “blochynes” seems to be relevant to the camera position, if I move the camera the blotches change.
Here is the .max file.
Image on the right is with the issue, left is when I turn off matte object in the mtl wrapper.
The blotches seem to be produced by the Light Cache when sampling a shadow catcher behind an invisible to the camera object. Either increase the Light Cache subdivs or use Brute Force/Brute Force instead.
Thank you..