Hide objects, but leave shadows on

lzh35925

Hi,

I have a scene of a room where there is a floor, walls, objects, characters and I want to render everything separately and put it together in a software, but if I hide something, it will also hide the shadows. When I put everything together, it just doesn't look real. Is it possible to somehow exclude items from the render, but keep their shadows on ? 
I tried this solution https://www.daz3d.com/forums/discussion/comment/4035871/#Comment_4035871 using the Create Advanced Iray Node Properties script, which adds an Iray Matte to the object, and then set the cutout opacity to 0.001, which hides the object and keeps the shadow on. It works pretty well for some objects, but not all objects cast shadows in the same way as when they are visible. In particular, hiding the walls with this solution will absolutely change the lighting of the room (it's much brighter) or objects change the cast shadows on the floor and then it doesn't look natural when I put it together in the software.

Are there any other tricks or dedicated asset I could try?

Richard Haseltine

You could simplify materials and do a shadow pass like that, getting rid of (or greatly downsampling) textures may reduce resources enough without having to remove objects.

lzh35925

I'm not sure what you mean. If I just lower the quality of the texture, the item will still be visible in the scene, it will just look like a smudge. And if I do anything else with the textures the light just changes and no longer works as intended. The problem is not the rendering time, I need all the items to be rendered separately, but lit exactly the same as if everything was in the scene.