I am trying to create a VFX compositing workflow, but am hitting a wall with the Shadow Matte shader. Pretty sure I'm having some fundamental misunderstanding here..
I can't figure out a way to generate accurate reflections through the Indirect Specular settings. When the scene's background image is visible, only the highlights are reflecting on the floor and not the dark values, creating a glowy/additive look. Dark objects totally disappear.
My set-up is simple: a floor (with shadow matte), a few primitives sitting on top, a light source, and a background object. The Shadow Matte is mostly default, with Indirect Specular Intensity set to 1, and IOR set to 0.
Look at where the objects touch the floor - the black cylinder disappears completely, the red sphere is practically glowing, and the green sphere's reflection doesn't have any of the shadowing from the underneath part.
With the background disabled, you can see how the problem goes away. Which to me implies that the shadow matte is getting blended in an additive way on top of the background image, completely cutting out all black values.
Here's my bad photoshop attempt to show what it should look like (or at least close to it, realistically the reflections wouldn't be that sharp)
Can someone explain what i'm missing? Is the solution to export everything as AOVs and composite them in AE/Nuke? I'm really trying to avoid that and get everything looking right in the viewport. Please help, thanks!
Here's the project file: