GPU Arnold ShadowMatte render issue

[YellowZ]

Hello,

I am fairly new to Maya and Arnold overall, doing my first more serious animation project. I've been using CPU to render most scenes however after switching to GPU i noticed huge difference so I stick with it. Unfortunately most of my scenes require using ShadowMatte for rendering shadows of objects in scene with alpha channel (basically doing matte painting method to replace background and floor). There's no problem with it in CPU mode however when using GPU there's no alpha channel and can't obtain transparency effect. Is there something that has to be adjusted differently than when using CPU mode for Arnold? I looked up some old issues regarding this problem but last one was from GPU beta, documentation says now that ShadowMatte is supported with some limits. Is it even possible to obtain this effect with current version?

I'm using the latest Maya with Arnold version.

I'd appreciate any help, best regards.

[lee_griggs]

There are currently some GPU limitations with shadow_matte I am afraid.