Thanks for the offers of help. The task is a very "on again, off again" affair so expect quiet times and busy times! (Depending on availability of new scans.) The steps are as follows:
1) Load map into gimp or similar. The images are 17000 by 21000 pixels which can be a strain on computer memory. 2) Resize to 50% of orginal. This seems sufficient and makes later stages faster to process. 3) Save as jpg 4) Note 9 calibration points that are appoximately evenly placed in a 3x3 grid. The map corners are used as calibration points. Each point has a map reference and pixel position. 5) Save that information in a text file as specified here: http://wiki.openstreetmap.org/wiki/Warp-gbos#Calibration_of_Sheets 6) To check the calibration, the calibration file can be used with the warp-gbos tool to create a KML file. The warp-gbos tool needs to be compiled from source. Details at the above link. 7) This can be compared to google-earth as a sanity check. 8) Send me the calibration file :) I will send people who have expressed an interest a link to download a map sheet to play with. Regards, Tim _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
