Volume Z-Depth Front - Back

[Snt]

Hello everyone,
I need to render z-depth for my volumes. I created a fogy and smokey environments for my client and it will be comp in Nuke. Compositing team asking me to render a z-depth. I know volume couldnt generate a z-depth on info channels. But when i select volume z-depth back and front, it rendering completely black. I'm using octane volume for general haze and VDB loader for smokes. I couldnt find any info about these render passes so i'm stuck

Thank you.

[Jengo_1]

Have you played around with the black and white values of the pass inside Nuke? Usually when it happens (in AE's EXtractoR plugin), I mess with the white/black point till the image starts to reveal itself, then I dial it in according to what I see. Sometimes I'll play with the levels to get more precise black/white adjustments.

[annisnaeem]

To answer your question; you need the Zdepth pass, not the volume front and back. You use the volume front and back when you have placed an actual volume in your scene. When not using a volume, and you're just trying to get some faint fog in your scene with the depth pass, that's all you need. Make sure you render 16 bit or 32 bit, and either tonemap in octane, or tonemap in Nuke. Either way, you'll initially see a pure white image in some cases and you simply have to use an exposure node to control it.