OTOY Forums

Analog to Render Layer IDs, you use Light Pass IDs:

OctaneRender Settings
Step 1: Check "Light Pass ID" in the "info passes" tab, to actually render the Light Pass IDs.
Step 2: Then select them as a preview pass to display.



Attribute Editor
Step 3: Select a light pass ID in for example the emission node of your diffuse material.



Result:

Cool, cheers for the info.

Just a quick question, do the ID's go:

1 Red
2 Green
3 Blue

4 Red
5 Green
6 Blue

7 Red
8 Green
9 Blue
etc.

nope...

Cheers.
Is there a way to make this R, G, B, R, G, B etc.
Makes things way easier for selecting and masking (when in RGB, of course ).

Cheers

well, just use light pass ID 73, light pass ID 18 and light pass ID 36, if you only want Red Green and Blue mask.

73 = Red
18 = Green
36 = Blue

But there must a misunderstanding here, "light pass ID" pass has a very few usage, it only creates color mask for the 8 groups of emitters respectively responsible of the 8 light passes...
(actually there is 10 light passes with ambient and sun pass , but only 8 with ID)

I am after multiple mattes (so sorry, this might not be the right thread), so let's say I have 20 objects which I want to mask, I would need 20 separate mattes.

The obvious choice would be the "Object ID" pass but it's broken at the moment ( I think K.A.Schubert is trying to take care of this ).

If you want to color correct objects but also depending on the shader, better to directly use the "shader ID" pass .

For unlimited number of mattes, use "render Layer ID" pass.
Though the primary purpose of the "render layer ID" pass is to easily control the contribution of the render layer dedicated passes ( Shadow and layer reflexion pass) .
But you can use "Render Layer ID" pass as a custom matte pass, assigning different render layer ID at whatever object you want.
And if you want only RED GREEN and BLUE mask, only use Render LAYER ID 73 , 18 et 36.

73 = Red
18 = Green
36 = Blue


It's a bit tricky to get a "render layer ID" pass, details here :
viewtopic.php?f=28&t=53027

Also for this workflow better to render this pass alone with the Info Kernel, render much quicker.

UPDATE: better to use the object layer colorpass now instead