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Shadow Pass Problem
I am trying to do multi-pass render where the animation is tracked a shot in 3D space.
Basically, in the scene, there are several objects that are dropping onto the a floor object within Cinema that is matched to the actual floor in the footage that the whole scene is tracked to.
I currently hiding the floor within Cinema from the camera so it does not render out along with the rest of the scene, but when I do this, I lose the nice shadows that go along with the floor. I can get the shadows back in the render if I check the “Seen by Camera” box in the compositing tag that I am using on the floor in the scene, but then I, of course, can’t seen the floor in the footage that I am tracking the scene to.I need to find a way to render out the shadows of the floor while not actually rendering out the floor itself.
Any tips? -
4 Replies
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You should render the floor. Just give it a compositing tag and check the “compositing background” option.
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That does work and I have done that before.
What I forgot to mention in my original post is that I am trying to get all of my multi-pass renders done in a single render.
If I leave the floor on and hit compositing background, then I have to do two renders in order get all of the proper elements in place for my compositing program.
In other words, I have to render the entier scene once for shadows, with the floor on, then render the whole thing over again, with the floor off and just my 3D objects in the shot.The real problem I am dealing with is that I am using the objects in my scene as ridged bodies and the dynamics engin is giving me slightly different results every time I am a render, so it is critical that I render everything at once.
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I’m still not sure why you can’t use the compositing BG option. Is it because you want an alpha for everything, and no floor? If so you can put everything but the floor in a null and then render an object buffer pass for the null.
Also, you might want to cache your dynamics objects so you can get consistent results in the editor/picture viewer.
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Awesome!
Thanks, man.
That did it.
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