Ruppel is a concept artist and production designer for games and animated films in addition to being a teacher.
I discovered Ruppel at one of my favorite blogs, Muddy Colors. This review of Ruppel's "Graphic LA" sold me on the book immediately. And the book does not disappoint.
I haven't yet fully applied Ruppel's methods but I'm confident that once I dedicate the time to his teachings, my painting will dramatically improve.
Check out Graphic LA and Ruppel's other work.