Matte shader for integrating CG with backplate

[xtimmyx]

In both VRay and mentalray as well I believe, there is a really handy shader for having mutual contribution of light between a CG object and a backplate projected onto geometry.

Essentially what I'm after is a way of rendering for example a teapot on a table, where the table is just a grid with a photo of the table projected on to it, and have the teapot cast shadows, reflections and indirect lighting onto the table, as well as having the table occluding, being reflected in and casting indirect light back onto the teapot. And here comes the trickiest part. Preferably this would be using PBR and work with the built in AOV:s.

Picture F below illustrates perfectly what I'm after:

http://www.buzzbox.eu/content.aspx?pid=37

So far I've found that if you disable diffuse, and plug the backplate into the emission of the surface model and multiply that with a shadow matte you end up with pretty much that result. However that obviously doesn't produce any diffuse AOV for the table, and the table backplate is being included in the beauty.

Sure there are workarounds for this and perhaps it impossible due to the nature of PBR. But if there is in fact a solution to this it would make integrating objects with backplates so much easier without having to separate all these things separate layers and so forth.

Cheers

[3dbeing]

I think if you check phantom in the object render tab, this will calculate it as if it was there but not render it.

[xtimmyx]

I think if you check phantom in the object render tab, this will calculate it as if it was there but not render it.

That's true. But will also remove the shadows, reflections and secondary light cast on the table.