Hey folks, I was curious: I often times find myself using the "difference matte" filter to pull a rough key, or get started on a roto job. However, it's sophistication is nowhere near the awesome software power of a tool like Keylight, for example.
My question is, are there any 3rd party tools that are more geared towards difference keys than color keys? In other words, any tools that are geared towards isolating objects on a complex background?
That's a darned good question.
AE's difference matte needs the backgrounds in both shots to be precisely the same to do any good. So no moving the camera, no messing with the iris & focus, no mixing codecs, etc. You'd think there'd be a better one, but I'm at a loss come up with any.
Using a difference matte, any difference matte that I've ever tried, requires identical exposure, no camera movement, no compression artifacts (which rules our 99.999% of all footage from DSLR's and proSumer cameras) absolutely no change in focus, and nothing around the subject you want to matte out can be moving, like leaves in the wind or water. In other words, unless you have uncompressed footage that's perfectly shot you won't be able to pull much of a matte. Like you, sometimes I have been able to pull kind of a garbage matte, but most of the time roto was my best option.
The biggest hint I can give you with roto is that you only need to do accurate roto where objects actually overlap. I've seen so many roto projects where careful attention was paid to an entire body when only the left arm and shoulder needed to be accurately masked.