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Why dont difference mattes work properly? Ever?
I love the idea of difference mattes but I have never, EVER got one to work properly in Premiere. After Effects isnt so bad but its still incredibly ropey. I’ve shot my background (my office floor) with manual focus, then rolled a green ball across the floor. I exported the first empty frame and used that as the difference matte. But it doesnt work! I dont understand why such a simple concept just never works. Is it me, or is the technique dodgy? If I could get this working it would be fantastic and really open up possibilities in my film making, but as it stands, I cant get it working at all. Any help much appreciated.
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3 Replies
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The problem is that the tripod is not as steady as we might want. Every pixel must be the same in both clips except for the ball. This is not easy with compression.
I suggest investing in a green screen.
Steven
https://www.stevengotz.com -
Yeah…I thinking compression is a horrible culprit when it comes to difference mattes.
It may look the same to you, but mathematically to the cpu…not the same…
ugh…
Alex
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Sorry to necro a thread but it seemed to make more sense than to create an entirely new one about this.
I just tried using a difference matte on CGI renderings. The avi is uncompressed, so this test case is as perfect as could possibly be. The difference matte still fails to locate the moving object.
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