AJ R wrote: > Now coming to the issue we are facing. When the layers are rendered on > the map due to some weird inexplicable reason > the 'ez' layer and 'mapBackGround' layer do not seem to be aligning > properly. There is a slight difference in the > rendering of the two layers. In addition as we move from top left hand > side of the screen to the bottom right hand, > the deviation increases. At higher zoom levels, the layers line up > almost exactly but not perfectly. Interesting. > Has any one ever faced a similar situation. I got a report of a similar problem (feature data and a MRSID file not lining up) three weeks ago - until I am able to reproduce the problem I was not going to annoy anyone. > If yes could you take a guess at where in the whole (PostGRes - WMS > server - GeoTiff renderer - PostGIS renderer - Mapbuilder/OpenLayer) > hierarchy could the problem lie? I suspect the raster resample code code - but that is only because it is how the problem was first reported to me. When we do a "resample" we actually take the inverse of the transform used by the feature data... DATA WORLD SCREEN Geometry -transform-> Geometry -transform-> Shape Image <-transform-> GridCoverage <-transform- pixel
The Data to World MathTransform is based on the referencing moodule, and usually the EPSG database; you are using epsg-hsql or something? epsg-wkt may not be quite as accurate. So the kind of error you are talking about could be due to MathTransform.inverse() not being quiet as accurate as the origional. To test try setting up a MathTransform in each direction and see how close the transformation is in one of the areas you are having problem. The World to Screen is usually an AffineTransform and is going to be of similar accuracy in both direction. > Also could you let me know if there is a more effective way to render > geotiff files as compared to the general mechanism i suggested in the > Rendering section above You are using the resample operation right? > In case the above information is not helpful I would be glad to > provide more information. I would appreciate any help with this issue. We should report the bug; and if your data is not private some screen snaps showing the problem would be helpful. All the best, Jody ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Geotools-gt2-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
