"John W. Blue via QGIS-User" <[email protected]> writes:
> I have downloaded historical highway maps in .png format that I would > like to georeference. Very cool; consider publishing the georeferenced versions. > Around the perimeter of the map are a few lines indicating lat and > long making it easy to be able to add a layer to draw straight lines > from left to right and from top to bottom. Which I was able to do. > From there I was able to get QGIS to find the intersections. > > And now I am stuck because I cannot save the intersections with > lat/long coordinates it only allows x,y. > > I am sure I am most likely doing something wrong out of the gate but > this seems like the logical direction to go in. The old maps have "lat and long", but what datum? Depends on where and how old. Basically pre-80/90s coordinates were different enough from modern ITRF that it is likely to be noticeable. I would just use the georeferencer in qgis against either imagery or openstreetmap and find a bunch of intersections. That throws away the original lat/long information but avoids "it is in NAD27" or "it is in the New England Datum" or however that is for where you are looking at. _______________________________________________ QGIS-User mailing list [email protected] List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
