Ambient Shadow Map with Alpha

radiancef0rge

Im looking for a way to bake out an ambient shadow map but have it respect the alpha of the meshes it's baking. 
I know you used to be able to do this in mental ray batch bake and Max may support it with the 'complete map'
However I am on Maya 2016 so mental ray is not an option, and I would prefer not to use Max. 

Has anyone successfully done this?

chrisradsby

It's always quite an issue rendering out alpha properly. I've managed to do some work with it in Modo. Maybe it's applicable on Max/Maya as well?

In modo I used stencils to be able to Bake out alpha cards properly. In all other software I've tried before I end up with issues with alpha sorting when trying to bake things down to a plane. When I tried it, even baking out AO/Depth worked with the alpha cards.

http://christofferradsby.com/blog/2016/12/20/modo-shenanigans-baking-down-alpha-cards

radiancef0rge

Thanks Chris, I ended up doing this with Mental Ray and Occlusion Deep which allowed the rays to pass through surface transparency when using an mia shader. 

kwyjibo

There is a kind of obscure attribute in the raytracing options for your material called shadow attenuation. Set it to zero and then you can bake out ambient occlusion and light maps that respect alpha.