Second test of a QR-code driven paper georeferencing system, now using two QR codes for more accurate positioning. See this page for information on decoding the georeferencing and this page for the earlier single-point system. This arrangement results in much lower geometric error, however if the bottom right QR code is clipped in scanning or otherwise rendered unreadable, the decoder could still fall back to using a single QR code for postioning. The layer "Scanned Map" is a scan of a printout produced by the link below. The paper map was then scanned and then automatically georeferenced. Currently I use ZXing to decode the QR code position, a Python script to generate the georeferencing, and Mapserver to render the tiles.