After Effects' Roto Brush - why it sucks

Professional roto artists are still using good old roto shapes, not After Effects' Roto Brush or anything like it. Watch this video to see why, although there are some situations where it might be useful. The book I refer to and use in my classes is Adobe After Effects CC Visual Effects and Compositing Studio Techniques by Mark Christiansen. It's a great resource. Buy it here: https://www.amazon.com/Effects-Visual-Compositing-Studio-Techniques/dp/0321934695/ref=sr_1_4?keywords=after+effects+visual+effects&qid=1551802462&s=gateway&sr=8-4