How to make a Matte material in Cycles?

How to make a Matte material in Cycles?

“The Matte/Shadow material allows you to make whole objects (or any subsets of faces) into matte objects that reveal the current background color or Environment map.”



In which render engine?

In Cycles.

You can try experimenting with the Holdout shader, but it will never catch shadows like its Max counterpart. It’s just an alpha “hole” in your image for later compositing.

I think you need to do that in post; use a 100% white diffuse material for the areas that are gonna be the background, then in the compositor you get a mask for just those areas and multiply the image on that area by the same areas in the background image.

If the other objects in the scene got reflections, refractions or should be lit by the background, things get a bit more complicated, you might need two passes; one for the shadows and stuff that are gonna be applied to the background as described above, and one where the objects that are gonna be replaced by the background got an Emissive shader (I’m assuming you’re working with Cycles) with the background image hooked to the color input, and using something like the Window output of the Texture Coordinates node for the UV, and if you wanna make it even more realistic, also have a Difuse shader mixed with the Emissive (and glossy for the reflective areas in the background, if any) to include those bounces in the light calculation for the 3d objects. And then composite everything once it’s done.