[OSGeo-Discuss] WCS/WMS accuracy tests?

Steven M. Ottens steven at minst.net
Mon Dec 7 09:56:41 PST 2009

On Dec 7, 2009, at 6:48 PM, Frank Warmerdam wrote:

> Steven M. Ottens wrote:
>> Hi all,
>> Working with Geoserver as a WCS we discovered that requesting a GeoTIFF in
>> the same projection as the original GeoTIFF produces a shifted dataset.
>> (http://jira.codehaus.org/browse/GEOS-3702) The shift is small, less than
>> one pixel of the original dataset, but with a coarse dataset of 100m/pixel
>> it can be 70meters. The Geoserver people are aware of the problem and at
>> some point in time will fix it I'm sure, but it prompted me to test other
>> OSS WCS servers (mapserver and deegree). Both of them showed a shift of the
>> data as well. Deegree has about the same error as Geoserver, while Mapserver
>> does a better job but is still off.
>> I know there have been speed tests between different WMS services, but I'm
>> wondering has there been any data-quality/accuracy test been done between
>> WMS and/or WCS services?
> Steven,
> I would appreciate your filing a detailed ticket on this issue against
> MapServer.  Please be specific about the exact request made, provide the
> data and mapfile, and explain why you think the results are wrong.

Will do once the tests are completed. Currently we overlay the original GeoTiff with the result of the request in QGIS. Other ways of testing are welcome. (I was thinking gdal-info output, overlay in uDig and ArcMap to rule out bias of QGIS)

> Best regards,
> -- 
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | Geospatial Programmer for Rent
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