Render layers problem maya 2018 and Arnold

[cyril.fassiau]

Hello guys, I have a little question for you :

I am trying to render a scene where smoke follows a car along a dirty road. The smoke taking a hell lot of time to render, I was wondering if I could render the smoke and the rest separatly.
But, as you can see in the screens, from the render camera (1st pic), the smoke goes right in the middle of the road, so when I render the environment, and then the smoke, I cant composite them together. (3rd and 4th pic)

Is there a way, in Maya 2018 with Arnold, to render them one by one and be able to compose them well? Thanks !

[lee_griggs]

Have you tried the Shadow Matte shader?

[cyril.fassiau]

Not yet, how should I use it to get the result I want?

[lee_griggs]

Try assigning it to the surrounding geo.

[Andrew_Wilkins1]

Not sure if you've gone through the Maya render setup docs?

https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2018/ENU/Maya-Ren...