Most of the tut's don't cover basic stuff, or they're some guy mumbling into the mic whilst clicking around trying to comp a specific scene - there's nothing to tell you what keyers to use when or what a n alpha is other than black=transparent. i don't grasp what all this premult and rgba.alpha is (ie. whats the difference between rgba and rgba.alpha..?)
Are alpha channels specific to one image, or can they operate on a number of images (ie. can I have a 'hole' in the middle of the scene, and have that hole cut through two or more images layed over each other? or do i have to assign the alpha 'hole' to both images. if the latter is so, what if I already have an alpha on that image, how do i keep the two separate?
In my frustration, I've tried to do a simple comp with a grass field as a bg, a car cut from a street scene over that, with a figure shot against a greenscreen for the fg. with the car moving across the field and behind the figure... and i can't even do that. I've fluked the roto round the car, and animating it across the field was easy. but i can't key the greenscreen. I just don't understand the principles of the rgba, the mask pipes, premults... I just don't get it!
I desperately need a helping hand on a few basic questions, the tutor in class was an industry guy - the lessons were ok when he was there and telling you what to click when things weren't right, but he's gone now so I've got no help to finish this comp. help!!
i understand this seems like a garbled rant but I'm running out of time and options and it's driving me insane!!