For figuring out chess pieces, maybe determining the light source and looking for light/dark patterns in certain areas? The problem is, from top view, even a human would have a difficult time figuring out if a piece was a bishop or pawn.
At least there are a lot more pawns than bishops on the field, typically. So you could easily test if the correct number of pieces were identified with a particular pair of pawn/bishop signatures.
Get hold of one of those automated chess boards that move pieces around by magnets under the board. Set it to replay old games, and film or photograph it. That should give you unlimited photographs of known positions.
