Zdepth render element

[SonyBoy]

Two questions about the zDepth pass:

1) Is there some reason by default this pass renders black as nearest to camera and white as farthest away? I'm not sure which is more common, but I've always rendered my depth passes the other way around, with white closest and black farthest away. This seems more intuitive and when dialing in depth settings makes it easier to "read" your farthest depth point as it places black objects (at maximum depth for blurring purposes) against the black background.

2) If I wanted to get the above result, you'd think that just setting the black and white points in reverse would achieve it, but when I do this the pass comes out with a white background, not black. This also seems unintuitive and still results in difficulty reading depth settings. Is this intentional and if so what is the rationale behind this?

Thanks!

[sharktacos]

Two questions about the zDepth pass:

1) Is there some reason by default this pass renders black as nearest to camera and white as farthest away? I'm not sure which is more common, but I've always rendered my depth passes the other way around, with white closest and black farthest away. This seems more intuitive and when dialing in depth settings makes it easier to "read" your farthest depth point as it places black objects (at maximum depth for blurring purposes) against the black background.

FWIW, Nuke assumes that far is white (when zdefocus is set to "depth"). Arnold works the same way.

2) If I wanted to get the above result, you'd think that just setting the black and white points in reverse would achieve it, but when I do this the pass comes out with a white background, not black. This also seems unintuitive and still results in difficulty reading depth settings. Is this intentional and if so what is the rationale behind this?

There is currently a bug in V-Ray that will cause the background to be black even though the far value is white. As a workaround you can create a sphere for the background:

1. In the Maya scene create a primitive sphere and scale it to be super gigantic. If you can't see it in the clipping planes, don't worry. V-Ray still can see it.
2. Apply a Surface material to it and set the matte color to black (so it wont affect the alpha)
3. Create a Vray Object Properties for it, and uncheck the following:
   • Visible to GI
   • Visible in reflections
   • Visible in refractions
   • Cast Shadows
   • Receive Shadows
   
   Leaving only "primary visibility" checked. This will cause the sphere to affect the zdepth, but not block the lights or environmental GI and so on.

[SonyBoy]

I guess Nuke friendiness is the reason for white being the far point then, although the comp lead here tells me it doesn't make any difference beyond the default settings on the zdefocus node.

Good to know it's a bug -- this makes a bit more sense.