Got a small Problem, i am trying to render out the VRayZDepth Channel but all i got is a pitch black image…i am using 3dsmax9 and vray 1.5 rc3.
i was using the overpass scene from christopher nichols vray exterior dvd and simply added the vrayzdepth channel in the render elements dialog. on the dvd he can have a look at the channel with the vray frame buffer, some nice black/yellow image, but all i got is a pitch black image… is it a bug or am i am doing something wrong ?
Olli
Using the render elements you need to set a start and end range for the zdepth to tell vray over what distance you want the dept of the scene to be mapped - It’s the distance in units from the camera you want the depth to start from and end. If you’re using a target camera, try moving the target along its axis to the plane you want the depth to start at. Use the modify panel read what the target distance is - this goes into the start distance of the zdepth render element. Now move the target to the furthest point away (again along its axis so your camera doesnt reframe) and read the target distance again, this becomes your end distance in the zdepth - if you think about it, a zdepth is a simple grayscale image and in the case of a huge scene you could end up with white really far off into the distance and a tiny bit of black in the front - you need to tell the renderer what range you’re interested in.
its the same problem like with my r2t thing… with rc2 it works..
whee, its working, thanks joconnell. it never came into my mind to scroll down a bit in the render elements dialog - silly me :roll:
Strangely enough, It happenned to me too at first. That’s very common if you are using a lower res secondary monitor. That’s the result of using a “clamped” dual monitor setup :lol:
Also if you untick clamp output and save it as a float image then it doesnt matter so much what you put for the min and max 
Yes ! But then it would be kind of hard to get the element as you want.
Vlado told me, that NUKE can manipulate it somehow.
Best regards,
nikki Candelero
hmm good point.
So its still best to use the min max. And not rely on unclamped z-depth.
But dont forget you dont need to re-render the whole image to get a fixed up zdepth.
So remove all lights use a plan vray materrial and crap render settings that will still output a good zdepth map to use with your proper render.
Thanks Nikki 
good info there DaForce 
Why thank you
lenscare will do the same thing nuke does.
basically it’s like adding a brightness contrast in AE, but with controls that affect the image or doing DOF.