I am trying to render a normal and position pass in Mantra. When I render to Mplay, everything works fine. I can even export from Mplay, all working.
But when I choose "Render to Disk", the Normal and Position Passes show up black in Nuke.

I've made a video illustrating the issue:
https://youtu.be/06fQwJOwj4o [youtu.be]

.hip file: https://drive.google.com/file/d/1817ltQxa3hq4T8rJ2ziqZRhDwvnmAlIc/view?usp=sharing [drive.google.com]

There may be an issue with the shop_materialpath that gets added in the pyro solver or the pyro bake. I think since you convert the vdb to a polygon that throws it off? I opened your shot and put down an Attribute Delete to get rid of that materialpath and it seems to work alright on my side.
Other issues may exist but that's where I would start.

Thanks for the answer Anthony!

I tried what you mentioned, I also tried exporting and re-importing the whole geo as .obj files, to make sure no unnecessary information is kept. It did not fix the issue.

However, experimenting a bit more I found out, that the "Shading Normal (N)" checkbox on the mantra node, as well as a custom Image Plane with "N" as VEX Variable and Channel Name both created a black "N" pass in Nuke. (In combination and by themselves)

Replacing the "N" channel name with a different string, eg. "Nr", it worked fine and I could view the Normal pass as "Nr" in Nuke.
This works with the "Shading Normal (N)" checkbox enabled or disabled.

I dont really now what to make of this...

This is the updated hip file: https://drive.google.com/file/d/1bkViAZW98HPo9EKj-WlIYFZINfDweo4X/view?usp=sharing [drive.google.com]

Anthony Morrelle
There may be an issue with the shop_materialpath that gets added in the pyro solver or the pyro bake. I think since you convert the vdb to a polygon that throws it off? I opened your shot and put down an Attribute Delete to get rid of that materialpath and it seems to work alright on my side.
Other issues may exist but that's where I would start.