Wireless short-distance identification of passive components

I am looking for a way to wirelessly identify chess pieces on a chess board. RFID would match if it would give me a location of pieces...Dose anybody has any idea?

Have you seen this one:- http://www.andreadrian.de/schach/#Selbstbau_Schachcomputer_SHAH

RFID would work but you need a reader under each square. Possible but either expensive or a lot of work.

Optical - Video Camera under the glass board looking at markings on under side of pieces.

Dead reckoning - you know where the pieces are to begin with, a hall sensor in each square and a magnet on each piece would detect a new square being occupied and one being vacated, so you know what went where.

Thank you for ideas. We can add to this calibrated weight sensors at each square in case different pieces has different weight (and then we need to recognize color ..)