[Gdal-dev] Which tool to add an offset?

Miller, Craig craig.miller at spatialminds.com
Tue Dec 22 13:41:03 EST 2009

Sounds to me like it has the incorrect datum set.  E.g. it says it's NAD83
but in reality is NAD27.

On Tue, Dec 22, 2009 at 8:12 AM, NopMap <ekkehart at gmx.de> wrote:

> Hi!
> I am building a map with several layers containing OSM geometry and
> hillshading+contours. The rendering chain for the hillshading is
> SRTM GeoTiff -> gdal_merge -> gdal_warp -> hillshading.exe -> mapnik
> Now I have the problem that the hillshading and the geometry do not
> quite match. It seems the hillshading is offset some constant distance
> to the north and west. I suspect as the offset looks like some 100m that
> this is a result of the sample size of the SRTM data and the particular
> hillshading algorithm.
> Now I am looking for a way to correct this offset, so that optically the
> shading rests in the expected position relative to the geometry. But I
> don't
> know how to do this. I have tried modifying the projections for gdal_warp
> with some false northing, but the results always remains the same.
> Any idea on how to move the hillshading 100m to the south?
> thank you
>    Nop
> --
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Craig Miller
Geospatial Software Architect
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