I have an intense scene with several million polygons and in order to render it without crashing I use the Vray frame buffer and save it as a vrimg file which I then convert into exr using the tool that came with Vray( Vrimg2exr converter).

In the picture you can see I used the "-info" command to find out what channels the vrimg file had and there it is written that the ZDepth channel is available but when I try to extract it but the text states that it's not available. What is the deal here?

Alpha, for example, is extracted just fine.

probabaly better to ask on a forum like evermotion or cgarchitect. not many people use vray around here.

i pretty sure you can open a vrimg in the image viewer in max and look at each channel and save it but not sure. its a long time since i used vray

If I remember correctly, Z-Depth just doesn't work with VRIMG.
You have to render it seperately.Not such an issue if it's for animation. You could even do the Z-Depth with gray unlit material on everything, so it renders fast. Z-depth is unrelated to any light or material properties, it's just geometry.

BTW dude, I see you just registered, but keep in mind this is mainly a game-art forum. For high-end rendering specific stuff, there's better places to ask. Not that i mind helping you, but it's just a remark.

I saw a tutorial a while back where as long as you're keeping it as a 32-bit float and not dropping it to 16 then you can just change the .vrimg extension to .exr when saving - no need to convert.

Thanks for the help guys, but I just figured out I made a really dumb mistake. You see, I used "Alpha" to extract the alpha channel and I thought that I had to type out the alias to get the channel. I typed "-channel ZDepth" when I actually had to type out "-channel VRayZDepth"!

Also, I will be posting some game art soon, but I also do high-end 3D stuff, because sometimes I don't want to be limited by texture map sizes and polycounts. Thanks again for your time.