[OSGeo-Discuss] WCS/WMS accuracy tests?

Steven M. Ottens steven at minst.net
Mon Dec 7 09:50:33 PST 2009

On Dec 7, 2009, at 5:47 PM, Stephen Woodbridge wrote:

> Steven M. Ottens wrote:
>> 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.
That's our feeling as well. Andrea mentioned that there's an issue with different interpretations on the location of a pixel (centre vs. top-left).

> 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.

I'll be doing more detailed tests tomorrow and will post an overview then with the exact versions and configurations and results if people want to reproduce them. I f people have suggestions for specific tests or configurations I'm happy to apply those if possible.

Going to test with the latest Geoserver nightly, Mapserver 5.6.0-rc1, Deegree 2.3 rc1 on a windows 2003 machine. With two different GeoTIFFs (one in epsg:4326 and one in epsg:3035)


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