<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">The bounding boxes (from EPSG) are in our database (at projfinder) and the SQL query checks the map center point against those boxes to then only do the distance calculation against those valid candidates.<div><br></div><div>A<br><div><br></div><div><br><div><div>On Nov 2, 2014, at 11:46 PM, Paolo Cavallini <<a href="mailto:cavallini@faunalia.it">cavallini@faunalia.it</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Il 31/10/2014 17:54, Aaron Racicot ha scritto:<br><blockquote type="cite">We played with something just like this last year (called projfinder):<br><br><a href="http://projfinder.com/">http://projfinder.com/</a><br><br>That is just a simple demo application that was a proof of concept. Center the map where you think your data is from, enter in a sample X,Y from your dataset and it tries to guess what projection your data is in. Nothing fancy like parsing arbitrary file formats etc… just simple X,Y from your data.<br><br>I gave a presentation on it at FOSS4G-NA 2013 (you can reference it here):<br><br>http://reprojected.com/blog/2013/05/28/foss4g-na-2013-was-a-home-run/<br><br>If you are interested in the code I can point you to it. In the end it is basically a simple web-service built around a PostGIS SQL query that does the distance calculations to percolate up likely projections against the EPSG database.<br></blockquote><br>Thanks Aaron for this. IMHO an even better option would be to explicitly add to<br>EPSG/proj.4 db the bounding boxes of validity for each projection: in this way,<br>client GIS could show only valid projections for a given map area, and this would be<br>a major usability improvement for all.<br>All the best.<br><br>-- <br>Paolo Cavallini - <a href="http://www.faunalia.eu">www.faunalia.eu</a><br>Corsi QGIS e PostGIS: <a href="http://www.faunalia.eu/training.html">http://www.faunalia.eu/training.html</a><br>_______________________________________________<br>gdal-dev mailing list<br><a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><br>http://lists.osgeo.org/mailman/listinfo/gdal-dev<br></blockquote></div><br><div>
-- <br>Aaron Racicot<br>Z-Pulley Inc.<br><a href="mailto:aaronr@z-pulley.com">aaronr@z-pulley.com</a><br>360-221-2441
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