CGTalk - How to use Gradient Backdrop for GI while keeping the Backdrop black?

View Full Version : How to use Gradient Backdrop for GI while keeping the Backdrop black?

earwax69

10-10-2010, 12:44 AM

Hi, this cause me trouble since a while...

Using the gradient backdrop is nice for achieve fast Global Illumination without having to load a HDRI or make a background map but it automatically become my backdrop while rendering. Normally it would not be a problem but if the background is not black, I cannot use pre-multiplied alpha in After Effects. The quality of my alpha is greatly reduced...

???
thanks

earwax69

10-10-2010, 02:17 AM

Ok, got the solution. I just need to go in the Compositing windows and add a black frame as Background Image. It keep my radiosity from the Gradient but show the black frame as backdrop.

thanks!

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10-10-2010, 02:17 AM

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