[gdal-dev] Non-EPSG projections, esri_extra.wkt and best practices

[Jorge Arévalo]

Hello, 

Let say I want to warp this raster file https://dl.dropboxusercontent.com/u/6599273/gis_data/utm.tif

>From its original projection, EPSG:26711, to Robinson projection, not part of EPSG. So, I need to provide the correct frame of reference, and GDAL will be able to do it. 

I could download the OGC WKT definition from http://spatialreference.org/ref/esri/54030/ogcwkt/, and pass the downloaded file to gdalwarp, like:

gdalwarp -s_srs epsg:26711 -t_srs robinson_file.wkt utm.tif utm_warped.tif

The thing is I'm working with an app that uses GDAL to warp raster files. The information this app handles (and it's hard to change) related with non EPSG projections is something like ESRI:54030. I know this is something that GDAL doesn't accept. But I see, in GDAL_DATA directory, a file named esri_extra.wkt. This file contains a line like this:

54030,PROJCS["World_Robinson",GEOGCS["GCS_WGS_1984",DATUM["WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Robinson"],PARAMETER["False_Easting",0],PARAMETER["False_Northing",0],PARAMETER["Central_Meridian",0],UNIT["Meter",1],AUTHORITY["EPSG","54030"]]

This is the number of the ESRI projection followed by the WKT definition. So, my question is: Is there any "right" mechanism, maybe provided by GDAL, to make the warping operation? Something that gets ESRI:54030 as input, looks in this file (or where needed) and gets the wkt definition as output, that can be safely used with gdalwarp.

Many thanks in advance, 

-- 
Jorge Arevalo
Freelance developer

http://www.krop.com/jorgearevalo
http://about.me/jorgeas80

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