Arnold.Extract vertex color information question

#1

Hey guys, I’m wondering if there is a way to extract color information within the Arnold and render it as separate AOV. I’ve tried AiUserDataColor but without success. This video demonstrates what I’m looking for. From 7.31
//youtu.be/JyfIPlKGGi8

#2

So what you’re after is some data that bifrost creates via a certain MR shader ?
And you want to render that out with Arnold as a separate AOV ?

I do not use Maya 2015 or bifrost but first thing to know is does Arnold support bifrost yet ?

/Risto

#3

No, it isn’t created via MR shader. Basically it is a color per vertex information written in alembic cache file as ColoSets.

#4

If its written into an alembic color set, you just need to import the alembic using the -rcs flag. Not sure if this is integrated into the Alembic importer in 2015, it isnt in any previous versions. Just create your import string by hand (Meaning copy the command output in the script editor really) Then just add -rcs after -mode import or anywhere before the file name really. This will recreate the color sets. Then toggle on Export Vertex Color in the Arnold section of the Shape nodes that you are rendering and your aiUserData color should pull the info you need.
One good thing about color sets is that you can preview the data easily in the viewport. If its there then you are 90 percent of the way to success…if you aren’t seeing anything when you toggle the view port display of your color sets, then don’t even bother trying to render it!
Hope that helps.
~Ben

#5

Thanks Ben! That’s what I was looking for! Now I have color information render out. Is there a way to render only one channel and normalize it’s value?

#6

ok! Got it! RemapValue node does this.

#7

Glad you got it working!