Zdepth and Transparency

[AdZanetti]

Guys, I have two FumeFx objects overlapping each other in my scene, one at foreground and the other one coming from background and moving to the front. My smoke is transparent and the Zdepth pass is not, any idea how to fix that, whether it's at compositing or at render time? I'm a bit reluctant to render out the Depth of field out of Max as it makes my workflow very rigid at compositing. Any Idea?

Thx

[Jordan]

Well, you cant really do a zdepth that is meaningful for transparent objects...
Thank about it... if black is 20m from the camera and white is 10m from the camera and you have a 50% transparent smoke at 10m, the zDepth would be giving you 50% gray (not white!), putting the smoke at 15m??? see, dosent make sense Then you have the problem that each pixel of smoke needs to represent different depths as you can see through the smoke.

The only real workaround is to render out deep pixel data. You can get a version of vray that supports saving out deep pixel data and comp it in the latest nuke that has deep pixel support. Chaos group has a nuke plugin to bring in the deep pixel data from vray.

[AdZanetti]

Thanks, didn't know about deep pixel data. Interesting, although i'm not willing to switch to Vray for the matter, nor invest in Nuke ...but ofr next time. FOr now, i just decided to split up my renders, background and foreground...

CHeers, A.