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?
I wonder if this is the difference between pixel as a point versus pixel
as an area. Mapserver uses gdal to handle GeoTiff files and Frank has
put a lot of effort in Gdal to handle this correctly.
Also, I'm surprised that there is any shift in mapserver because I do
not think mapserver reprojects data if the in and out projections are
the same. I can speak for the other services as I don't know how they work.
-Steve W
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