Matte object shadow Question/Problem

[Guest]

Hello Everyone.

I always have problems with matte object shadows that are overlapping with other shadows. It is difficult for me to explain my problem, but I hope you can see what I mean with the attached Images:

The Final Image:


I rendered the Environment (Road with Trees and the Car is hidden)


Then I unhide my car, select the Trees and the Road and in the Vray properties I do Matte -1 and check the "Shadows" & "Affect alpha":

this is the alpha.


If I put this together the result will look like that:


What I did in the past, I rendered the Environment with the shadow of the car: (See the next Post because I only can attach 5 images)

[Guest]

In a second pass I rendered the Car without shadows and this looks fine then:


And my question now is if there is any way to render the Environment without the Cars shadow. So I can change the movement of the car and do not need to render the Environment again.
I know in my case I can only render the road with the shadows again and put in on top of the Environment, but I hope I can stay with 2 Layers.

I have a Max 2014 and Max 2016-File attached

[Svetlozar Draganov]

I don't think there is a way to do that. The problem is that the shadows of the trees cannot be clipped by the car when the car is missing.
The easiest option maybe would be to use V-Ray Sphere Fade feature and render the car along its shadow, that approach will preserve the 2 layers setup and will allow you to change the path of the car without having to recalculate the environment layer.

[Guest]

Ok, so you mean i will render the Environment without car and shadow and in the 2nd pass i render again everything + the Car but i have to link a V-Ray Sphere Fade to the Car. So i only render the Car with the sphereregion around the car and the shadow. Right?

[Svetlozar Draganov]

Yes, that is exactly what I meant.
Another option would be to remove the overlapping shadows by using lighting/shadows render elements and matte-shadow masks but this will require additional render passes and the end result might have some artifacts.