Author Topic: Custom frame buffer bitmap?  (Read 1336 times)

2020-06-16, 09:46:32

joonior1985

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Hi there,

sometimes it comes to render an element of the scene separately (via "viewport selection" or by Gbuffer ID) and combine it with pre-rendered image. The  problem is that when doing such thing renderer samples the boarders of particular scene object on a black CFB background which gives an annoing black fringe around it. In some cases "defringe" option in Photoshop doesnt work properly (glossy or refractive surfaces, not mentioning hair, grass or any object with high frequency of it's detail). Is it possible anyhow to swap black CFB background to a custom bitmap so it could sample fringes with it?

Cheers!

2020-06-17, 17:20:00
Reply #1

maru

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How exactly are you saving and loading your images? If you are rendering one object against black background, you should not be getting black fringes.
Here is an example:
- full.jpg - full render from 3ds Max
- bird-selection.jpg - viewport selection mode
- bird-compo.jpg - viewport selection saved in EXR format with alpha channel, then background replaced with PS with a white solid color

2020-07-01, 16:09:58
Reply #2

joonior1985

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Hi,

sorry for late reply but was busy recently. In the attached images is an explanation. Once merged in Photoshop fringing appears. That's obviously because of black background is sampled when rendering via "viewport selection" or "Object Gbuffer ID". VRay solved that with easy VFB background swap option. Small and rarely used feature but how convinient in scenarios like mine.

Cheeeers!

2020-07-02, 13:51:30
Reply #3

maru

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In your example, there is a bright border around the object, not black. And this is because in the image Background.jpg the flower is rendered against white background. The issue is not because you are rendering the sofa against black background. It is because you are rendering the plant against white background.

Another thing is that PROPER COMPOSITING SOFTWARE (aka NOT PHOTOSHOP) would be able to correctly blend such images. So try Fusion instead (it is free).