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.
A On Nov 2, 2014, at 11:46 PM, Paolo Cavallini <[email protected]> wrote: > Il 31/10/2014 17:54, Aaron Racicot ha scritto: >> We played with something just like this last year (called projfinder): >> >> http://projfinder.com/ >> >> 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. >> >> I gave a presentation on it at FOSS4G-NA 2013 (you can reference it here): >> >> http://reprojected.com/blog/2013/05/28/foss4g-na-2013-was-a-home-run/ >> >> 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. > > Thanks Aaron for this. IMHO an even better option would be to explicitly add > to > EPSG/proj.4 db the bounding boxes of validity for each projection: in this > way, > client GIS could show only valid projections for a given map area, and this > would be > a major usability improvement for all. > All the best. > > -- > Paolo Cavallini - www.faunalia.eu > Corsi QGIS e PostGIS: http://www.faunalia.eu/training.html > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev -- Aaron Racicot Z-Pulley Inc. [email protected] 360-221-2441
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