This is a caustic directional map of a teapot. Each layer represents light from a different latitude: The inner layer is at 90 degrees, the next at 75, then 60, 45, 30, and 15. Then each image within the layer represents a different longitudinal angle. The images are arranged roughly corresponding to where the caustic would shine for light hitting from that specific direction; thus, an image at the top left corresponds to light coming in nearly horizontally from the bottom right.

This is a result of non-interactive pre-processed ray tracing that presents a designer with a wide array of possible directional caustics all at once, in an intuitive manner.