I have a series of tif-format maps that have long-lat fiducial markings only along the map borders. There no internal fiducial 'crosses' marked on the interior, as do most USGS topo maps. The border marks do not sit at the map corners either. Using Didger I can find the x,y coordinates of a border mark, but actually I only have, say, the x-coordinate for a specific longitude on the northern map border. I can also find the x,y value for a corresponding latitude value, corresponding to the y-value of a specific latitude on the western map border. But Didger requires a mouse click on the map interior location to calibrate the long-lat value at that location. Does any version of Didger provide for this situation for map calibration?
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