Roaming Ralph Tutorial
This tutorial shows a character walking on uneven terrain. He rises and falls with the contours of the terrain, stops when he runs into a tree or a rock, and won't walk off the edge. The camera follows him, also moving intelligently over the terrain, and you have some control over the camera angle. The character's body animates sensibly according to his motion.
Much of this is implemented using collision rays to detect the height of the terrain and the presence of obstacles.
The image below shows the tutorial in action.