This must have been covered before, but I can’t find a post.
I need to render out a whole sequence of multimatte elements (5 of them) but I don’t want to re-render the actual rgb frame - just the multimatte elements.
Is this possible as presumably it would be much quicker than re-rendering everything?
Not as such but if you turn off lights and shadows and put on a flat black material in the override slot it’ll whip through quite quickly. Unfortunately the render elements are a consequence of the full render so you can’t render just one aspect of the final image.
Check the RenderMask script. Has saved me days of rendertime when I just need to make masks. If you uncheck the “Use VRay Render” it uses the scanline instead and it is just lightning fast.
Absolutely - only thing is it won’t support vray dof or motion blur so your mattes won’t line up.
No, not with the scanline but with the VRay it does. Tyhe nice thing is it doesn´t render the whole image, just the mask, which is a great timesaver in some cases.
Yes, I’ve used RenderMask on many occasions and it is great. I just had all my 5 3-channel MultiMattes set up, so thought it would be nice just to re-render from there rather than using RenderMask.
Also, scanline AA won’t match up correctly, so although lightening fast (I sometimes miss scanline!), it isn’t ideal.
I know that render elements are a consequence of the rgb beauty pass, but I had hoped MultiMattes were different as they are referring to the IDs of the objects only, and so they *could* be rendered independantly. Oh well.
I am resorting to an overide black material, but it does have its drawbacks: materials etc are still all loaded at rendertime, even though there is an overide on everything - this takes time. Also, I need to save each black-overide rgb-beauty image somewhere in order for it to save the MultiMatte images. This is a pain and can easily lead to mistakes with files being overwritten.
Mind you that you might get non-matching AA/Moblur when not rendering the actual RGB as the sampling might be a lot different. Esp with black there wont be any oversampling i’d guess.
Regards,
Thorsten