Shadow render pass in MR

#1

Hi guys,
I’m having problem rendering Shadow pass using “Render pass” features inside Maya (Mental Ray). My objective is to render the diffuse and shadow pass separately using render pass in MR. But it seems the shadow render pass kept giving me problem.

Combining (ADDING) Shadow pass or Shadow RAW with Diffuse No shadow IS NOT EQUAL TO Diffuse. This confused me a lot. Shouldn’t adding those to passes give me the exact color/images of Diffuse pass ?

Here’s the render passes that I rendered:

Ambient

Diffuse

Diffuse Material Color

Diffuse No Shadow

Direct Irradiance

Direct Irradiance No Shadow

Indirect

Shadow

Shadow RAW

Master Beauty

The only time I managed to match exactly to Beautypass is when I render Diffuse+Shadow altogether in 1 renderpass. Is this a bug or perhaps limitation in render pass ?

Thank you.

#2

Bump. Could anyone help please ?

#3

You shouldn’t work with shadow passes at all, because shadows aren’t really “a thing”. Shadows are just the absent of light.
(It is possible to combine those raw passes with multiply I believe, but it’s always difficult to get back to your original beauty.)

The physically correct render pass recipe for mia in mental ray goes like this:
diffuse
indirect
specular
reflection
refraction

If you add all these passes you’ll get back to your beauty. :slight_smile:

#4

Hi Actinidia,
Thank your for post.
So is that mean we don’t separate the Diffuse and Shadow as a separate pass ?
But what if, for examples the shadow is too dark and we want to lighten it up ? Having Diffuse + Shadow together as a single layer, would be difficult to edit right?

Thank you.

#5

You can for example increase your gamma in post. This will mainly lighten up dark areas. With a clown matte you can do that per object.