  What does bumping into things in a scene tell you about scene geometry? In
this paper, we investigate the idea of learning from collisions. At the heart
of our approach is the idea of collision replay, where we use examples of a
collision to provide supervision for observations at a past frame. We use
collision replay to train convolutional neural networks to predict a
distribution over collision time from new images. This distribution conveys
information about the navigational affordances (e.g., corridors vs open spaces)
and, as we show, can be converted into the distance function for the scene
geometry. We analyze this approach with an agent that has noisy actuation in a
photorealistic simulator.
