Mental Ray/After Effects/White Ring around objects (Help)

#1

Hey Everyone,

I am having a major issue with my project here, and not really anyone to help. We have to create an animation, which is no problem. I am using Mental Ray to Render, but due to the size/length and render time, I have to render the background seperate from the animation. That part is no problem, I created render layers and rendered the bg and the animation separately. When I bring them into After Effects a problem occurs. I put in the background, then bring in the targa files (of the animation itself), when I put the two layers down, there is a white line, or edge over the animation layers. The background looks fine, but, like I said, there is this ugly ring around stuff. Screen shot taken to show you what I mean:

As a note: I am using physical sun and sky, I have gamma corrected everything.

#2

You need to refine your alpha channel cutout. I can’t recall the command in AE precisely, but “clamp” comes to mind. In Photoshop, you’d simply refine your selection.

#3

Hrm…

I’ll take a look for that. Maybe I can find it.

Thanks

#4
  1. make sure your rendering on a black background
  2. Make sure “premultiply” is on in mental ray
  3. Make sure you set your alpha to “premultiply” in after effects
#5

Thank you, I’ll try that. One question though; if I am using mental ray’s physical sun and sky… how would I render the animated part on a black background if a sky is created automatically?

#6
  1. Make sure you set your alpha to “premultiply” in after effects
    You may also choose the color you premult with in AE. Does work with solid backgrounds only of course.

Thank you, I’ll try that. One question though; if I am using mental ray’s physical sun and sky… how would I render the animated part on a black background if a sky is created automatically?
Try rendering out the background as a seperate image sequence, use it with mr’s background switcher shader for lighting and reflections on the objects in scene but keep the background black.

#7

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