Ten particles move linearly at random speeds. For each pixel, sort the set of distances from the pixel to each particle. Determine the minimum difference between these distances. Color the pixel a grey level that is an increasing function of this minimum difference.

The primary structure seen in this video is the black lines which are each the set of point equidistant to a pair of particles (that is, the perpendicular bisector of the line segment connecting a pair of particles). With 10 particles, there are 45 such lines.

Occasionally, the frame goes black; this happens when two particles collide, so that the distance from any pixel to those two particles is (essentially) equal, so every pixel gets colored black.

Made with Processing ( processing.org ).