<html><head></head><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:13px">Hi,<br><br><div id="yui_3_16_0_1_1449683769002_6382" class="" style="font-family:tahoma,sans-serif;display:inline"><div id="yui_3_16_0_1_1449683769002_7048" dir="ltr">I am downloading an open source .asc elevation files from <a class="" id="yui_3_16_0_1_1449683769002_6384" href="http://opentopo.sdsc.edu/raster?opentopoID=OTSRTM.042013.4326.1" target="_blank">opentopography.org</a>. I attached one of them in this email. Once downloaded .asc elevation file need to be projected from WGS84 datum (<a class="" id="yui_3_16_0_1_1449683769002_6386" href="http://spatialreference.org/ref/epsg/4326/" target="_blank">EPSG 4326</a>) to Universal Transverse Mercator. Here is an example of how this looks like in python GDAL for <a id="yui_3_16_0_1_1449683769002_6583" class="edited-link-editor" href="https://www.google.rs/maps/place/Barcelona,+Spain/data=!4m2!3m1!1s0x12a49816718e30e5:0x44b0fb3d4f47660a?sa=X&ved=0ahUKEwjv4relsc_JAhXEBiwKHe1BBVgQ8gEIejAO">Barcelona Spain</a> downloaded elevation model:</div><br class="" id="yui_3_16_0_1_1449683769002_6390"><div class="" id="yui_3_16_0_1_1449683769002_6392" style="margin-left:40px"><div id="yui_3_16_0_1_1449683769002_6894" dir="ltr">gdalwarp -s_srs EPSG:4326 -t_srs EPSG:32631 -r cubic BarcelonaWGS84.asc projectedToUTM.tif</div></div><br class="" id="yui_3_16_0_1_1449683769002_6396"></div><div id="yui_3_16_0_1_1449683769002_6398" class="" style="font-family:tahoma,sans-serif">So in this case the <a class="" id="yui_3_16_0_1_1449683769002_6400" href="http://spatialreference.org/ref/epsg/32631/" target="_blank">EPSG:32631</a> has been used as a projection (it hasn't been picked by me), it was googled.<br class="" id="yui_3_16_0_1_1449683769002_6402"><br class="" id="yui_3_16_0_1_1449683769002_6404"></div><div id="yui_3_16_0_1_1449683769002_6412" class="" style="font-family:tahoma,sans-serif"><div id="yui_3_16_0_1_1449683769002_6634">But how do I know which projection to pick, depending on the location for which the elevation data is downloaded?</div><div id="yui_3_16_0_1_1449683769002_6635"><br></div><div id="yui_3_16_0_1_1449683769002_6636">I googled a bit, and there are <a id="yui_3_16_0_1_1449683769002_6842" class="edited-link-editor" href="https://source.opennews.org/en-US/learning/choosing-right-map-projection/">few articles</a> online, which suggest picking the right EPSG projection based on UTM zone to which the downloaded elevation model belong to:</div><div dir="ltr" id="yui_3_16_0_1_1449683769002_6638"><a id="yui_3_16_0_1_1449683769002_6639" href="https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system#/media/File:Utm-zones.jpg">https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system#/media/File:Utm-zones.jpg</a><br></div><a class="" id="yui_3_16_0_1_1449683769002_6416" href="https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system#/media/File:Utm-zones.jpg" target="_blank"></a><br class="" id="yui_3_16_0_1_1449683769002_6426"></div><div id="yui_3_16_0_1_1449683769002_6464" dir="ltr">But I am not sure I understand how to choose the EPSG projection based on UTM zone.<br><br>How can this be done?<br><br>Thank you for the reply.<br><br>Kind regards,<br>Djordje Spasic<br></div></div></body></html>