<!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;'>There have been some more knowledgeable responses than mine, but they do make me ask:<br>Why doesn't QGIS have a generic Coordinate System for X/Y in meters (and maybe one in feet for the less developed nations ;-) )? It would be particularly useful for non-geographical datasets and would open QGIS up to being used more readily in other fields.<br><br>Similarly, it could have generic projections for equal area and equal distance calculations too. I know these are all possible because FME has all these features.<br>After all, there's no reason spatial data has to be GEOspatial data.<br><br>Cheers,<br>Jonathan<br><br><br><div class="zmail_extra"><div id="1"><br>---- On Fri, 06 May 2016 16:28:45 +0100 <b>Lee Hachadoorian<Lee.Hachadoorian+L@gmail.com></b> wrote ---- <br></div><blockquote style="border-left: 1px solid #0000FF; padding-left: 6px; margin:0 0 0 5px"><div><div>Simon,<div><br></div><div>You *must* specify a projection, but within some limits, the projection doesn't matter. Basically, if the GeoTIFF uses units of meters and you want your distances in meters, you can load the GeoTIFF in *any* projected CRS that uses meters. An example would be to use any of the UTM zones. You cannot use a lat-long CRS such as the default WGS 84, because QGIS will convert (naively, *not* using great circle distances) from decimal degrees to meters.</div><div><br></div><div>Once the layer is loaded, all geometry calculations are done in a Cartesian plane.</div><div><br></div><div>I answered a similar question on <a href="http://GIS.SE" target="_blank">GIS.SE</a> regarding someone who wanted to use QGIS to map indoor location data.</div><div><br></div><div><a href="http://gis.stackexchange.com/questions/187699/how-to-create-a-qgis-map-of-unprojected-data" target="_blank">http://gis.stackexchange.com/questions/187699/how-to-create-a-qgis-map-of-unprojected-data</a><br></div><div><br></div><div>Best,</div><div>--Lee</div></div><div><br><div>On Fri, May 6, 2016 at 10:12 AM, Jonathan Moules <span><<a subj="" mailid="jonathan-lists%40lightpear.com" href="mailto:jonathan-lists@lightpear.com" target="_blank">jonathan-lists@lightpear.com</a>></span> wrote:<br><blockquote style="margin: 0 0 0 0.8ex;border-left: 1.0px rgb(204,204,204) solid;padding-left: 1.0ex;"><u></u><div><div style="font-size: 10.0pt;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><div><br>---- On Fri, 06 May 2016 13:33:47 +0100 <b>simonc8<<a subj="" mailid="simoncrombie%40onetel.com" href="mailto:simoncrombie@onetel.com" target="_blank">simoncrombie@onetel.com</a>></b> wrote ---- <br></div><div><div><blockquote style="border-left: 1.0px solid rgb(0,0,255);padding-left: 6.0px;margin: 0 0 0 5.0px;"><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></div></div><br></div></div><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><br></blockquote></div><br><br><div><br></div>-- <br><div>Lee Hachadoorian<br>Asst Professor of Geography, Dartmouth College<br><a href="http://freecity.commons.gc.cuny.edu/" target="_blank">http://freecity.commons.gc.cuny.edu/</a></div> </div> </div></blockquote><br></div><br></div></body></html>