On Fri, Feb 11, 2011 at 9:40 PM, Ariel Nunez <[email protected]> wrote: > Hello list, > > We recently hit a roadblock while writing unit tests for an > application that uploads data to GeoServer, the problem we > encountered was that there were important differences between the data > uploaded to GS and then downloaded via WCS. > > Specifically: > The bounding box by something in the order of 10% > The number of rows and columns of the array (i.e. the shape) by +/- 1. > This means that the original array cannot be compared directly to the > downloaded array as they are not aligned. > The origin and pixel size by a few % (This means that the > georeferencing of the grid is changed) > The grid values themselves are also not exact showing some quite large > spikes in some places although viewing the TIF files (before and after > passing through GeoServer) shows that they are overall qualitatively > similar. > > I submitted a bug report [1], but I am raising the issue here to get > input from people familiar with the WCS codebase, first to verify if > it's a real limitation in GeoServer, and second to ask for pointers > about places in the code to inspect for possible optimizations.
For sure one of the differences is the half a pixel shift that happens because of the different pixel interpretation (area vs point, OGC mandates point, GDAL uses area). That is a GDAL bug that has been fixed in 1.8.0: http://trac.osgeo.org/gdal/wiki/rfc33_gtiff_pixelispoint The issue with the different number of pixels might be of different nature, but WCS on 2.0.x won't be touched anymore since the code base on 2.1.x is quite a bit different (making any back port an expensive time sink) so I suggest you first try out 2.1RC1 and eventually update the bug report with your findings Cheers Andrea -- ------------------------------------------------------- Ing. Andrea Aime GeoSolutions S.A.S. Tech lead Via Poggio alle Viti 1187 55054 Massarosa (LU) Italy phone: +39 0584 962313 fax: +39 0584 962313 mob: +39 333 8128928 http://www.geo-solutions.it http://geo-solutions.blogspot.com/ http://www.youtube.com/user/GeoSolutionsIT http://www.linkedin.com/in/andreaaime http://twitter.com/geowolf ------------------------------------------------------- ------------------------------------------------------------------------------ The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE: Pinpoint memory and threading errors before they happen. Find and fix more than 250 security defects in the development cycle. Locate bottlenecks in serial and parallel code that limit performance. http://p.sf.net/sfu/intel-dev2devfeb _______________________________________________ Geoserver-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geoserver-devel
