<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta content="text/html;charset=UTF-8" http-equiv="Content-Type"></head><body ><div style='font-size:10pt;font-family:Verdana,Arial,Helvetica,sans-serif;'>Hi Simon,<br>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?<br><br>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).<br>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.<br><br>Cheers,<br>Jonathan<br><br><br><div class="zmail_extra"><div id="1"><br>---- On Fri, 06 May 2016 13:33:47 +0100 <b>simonc8<simoncrombie@onetel.com></b> wrote ---- <br></div><blockquote style="border-left: 1px solid #0000FF; padding-left: 6px; margin:0 0 0 5px"><div>I want to use QGIS to make measurements such as distances and angles on a<br>flat scaled image which I have as a georeferenced tiff. I don't want to use<br>any projection - just a straightforward orthogonal linear scale in metres.<br>QGIS seems to require that I choose a projection. What would be the best<br>choice for my needs? Can I make a custom projection with no ellipsoid or<br>datum?<br><br>If I import my geotiff and don't specify a projection QGIS assumes my units<br>are in degrees rather than metres, which will make measurement of distances<br>and angles inaccurate.<br><br>Grateful for assistance. <br><br><br><br>--<br>View this message in context: <a href="http://osgeo-org.1560.x6.nabble.com/QGIS-project-with-no-projection-tp5264924.html" target="_blank">http://osgeo-org.1560.x6.nabble.com/QGIS-project-with-no-projection-tp5264924.html</a><br>Sent from the Quantum GIS - User mailing list archive at Nabble.com.<br>_______________________________________________<br>Qgis-user mailing list<br><a subj="" mailid="Qgis-user%40lists.osgeo.org" href="mailto:Qgis-user@lists.osgeo.org" target="_blank">Qgis-user@lists.osgeo.org</a><br>List info: <a href="http://lists.osgeo.org/mailman/listinfo/qgis-user" target="_blank">http://lists.osgeo.org/mailman/listinfo/qgis-user</a><br>Unsubscribe: <a href="http://lists.osgeo.org/mailman/listinfo/qgis-user" target="_blank">http://lists.osgeo.org/mailman/listinfo/qgis-user</a></div></blockquote><br></div><br></div></body></html>