Hi Simon, If you know the real-world width and height of the area covered on the image, could you not geo-reference it to have lower-left at 0,0, and then the top-right at the applicable location in the projection of your choice, and then work from there?
The problem is picking an applicable projection. I can't see any generic "X,Y" projection, let alone one that is suited to equal-area or equal-distance in the projections list. They may exist, I'm just failing to find them. They all seem to assume they're "somewhere" in the world (which can be a problem if the data is spatial but not geographical). Personally if it's a relatively small area (a few km across), I'd probably just use a standard Mercator for the applicable part of the world probably. Cheers, Jonathan ---- On Fri, 06 May 2016 13:33:47 +0100 simonc8<[email protected]> wrote ---- I want to use QGIS to make measurements such as distances and angles on a flat scaled image which I have as a georeferenced tiff. I don't want to use any projection - just a straightforward orthogonal linear scale in metres. QGIS seems to require that I choose a projection. What would be the best choice for my needs? Can I make a custom projection with no ellipsoid or datum? If I import my geotiff and don't specify a projection QGIS assumes my units are in degrees rather than metres, which will make measurement of distances and angles inaccurate. Grateful for assistance. -- View this message in context: http://osgeo-org.1560.x6.nabble.com/QGIS-project-with-no-projection-tp5264924.html Sent from the Quantum GIS - User mailing list archive at Nabble.com. _______________________________________________ Qgis-user mailing list [email protected] List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
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