[gdal-dev] Querying Geographic Coordinate System from an existing image file.

[Kyle Shannon]

Jim,

On Mon, Jun 8, 2015 at 10:11 AM, Tilton, James C. (GSFC-6063)
<james.c.tilton at nasa.gov> wrote:
> I seem to be missing some key point in understanding the use of OGR
> Projections.
>
>
>
> The OGR Projections Tutorial (www.gdal.org/osr_tutorial.html) very clearly
> describes how to set up a new OGRSpatialReference,
>
> but does not tell how to determine and query the OGRSpatialReference from an
> existing image data set (e.g. and GeoTiff image).
>
>
>
> Could someone please point me to examples/instructions on how to do this?

See gdalsrsinfo:

http://www.gdal.org/gdalsrsinfo.html

and the source:

https://trac.osgeo.org/gdal/browser/trunk/gdal/apps/gdalsrsinfo.cpp

For a geotiff, it'd be something like:

GDALDatasetH hDS = GDALOpen("mytiff.tif", GA_ReadOnly);
const char *pszWkt = GDALGetProjectionRef(hDS);
OGRSpatialReferenceH hSRS;
hSRS = OSRNewSpatialReference(pszWkt);

using the C API (and not doing error checking, obviously).

>
>
>
> Thanks.
>
>
>
> Jim Tilton
>
> ________________________________
>
> Dr. James C. Tilton                                               Voice:
> 301-286-9510
>
> NASA Goddard Space Flight Center                   FAX:     301-286-1776
>
> Mail Code 606.3                                                    E-Mail:
> James.C.Tilton at nasa.gov
>
> (Computational & Information Sciences and Technology Office)
>
> Greenbelt, MD 20771
>
> URLs:
> http://science.gsfc.nasa.gov/sed/index.cfm?fuseAction=home.main&&navOrgCode=606
>
> and . http://geography.wr.usgs.gov/science/croplands/index.html
>
>
>
>
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-- 
Kyle