There are just 32 pieces on a chessboard, but the number of patterns in which those pieces can move in the course of an individual game are astronomical. Still, as these maps show, despite all those different possibilities, each piece has a pretty clear pattern behind it.
The maps, which track the most common trajectories of each chess piece, are the works of Steve Tung. Tung explained the process behind the maps to io9, noting that each map represents condensed data from over 2 million individual games of chess:
I downloaded the Million Base chess database of ~2.2 million chess games http://www.top-5000.nl/pgn.htm (click the link ‘Million Base 2.2’). Then I ran the ~1.5GB database through a program called pgn-extract to reformat the data and a custom Python program to make a list of moves and the total number of times they take place for each chess piece.
For each entry on that list, a node.js program draws a faint line for every 500 times (rounding up) that the move occurs. Each curve’s start and end points correspond to the move, and its middle point is offset to give the curve both direction and height, with a little bit of noise added in so the curves don’t clump up too much.
You can check out the maps below, one for every category of piece, or see the full set right here.