View Full Version : Render Y value as a mask?

03-09-2008, 05:03 PM
Is there any way to render a Y value mask of a scene the same way we can render the depth (distance from camera) mask of a scene? This would be useful for putting in ground fog into a render in post.

I wasn't sure if any of the render buffers let you do this. I looked through the image processing options and didn't find any.


Jim M
03-09-2008, 05:35 PM
One way is on a surface level.

03-09-2008, 06:06 PM
if you`ve got dponts NodePixelFilter, you can do this with a gradient set with the y coordinate input

03-09-2008, 07:28 PM
Thanks guys, I'll look into those. I'd rather not have to re-surface objects to render out the mask, and I think that plugin is win only. I know I can do the surface gradient solution if I have to, though. Thanks again for the assistance.

03-09-2008, 10:39 PM
here's an odd thought... and might take too long to render be usefull.

1) set all your objects to be white matte objects.
2) add a black plane (could also be set to matte) and set it at the base of your objects.
3) enable fractional keyframes
4) move the plane up in the Y axis on frame .5
5) go into the graph editor and set the Y channel to repeat
6) turn on motion blur, set AA and render
7) adjust the height of the plane as necessary

I'm thinking that should give you a black base that fades up to white.

03-10-2008, 01:19 AM
turns out you can do this in the normal image filter, use a gradient in the textured filter and one of the input options is image y

Jim M
03-10-2008, 03:17 AM
Resurfacing is pretty quick though Jeffrey, I mean all you do is apply a preset to all surfaces in one go and hit render...

03-11-2008, 02:37 PM
Thanks Dana; I'd probably just resurface the objects on a copy of the file before doing all of that. I appreciate the help though.

LightFreeze: I'll have to look into that. I haven't fooled with the normal image filters at all! Cheers!

Jim: Yes, you're totally right. I'll probably just do that if I have to. It just seems like there would be a simple way to render a Y buffer image. :)