> What about an approach where the out-of-bound values are assigned the last > value only if reprojection is used (and if the layer does not have a null > value)?
My two cents, from a user perspective. We're facing this dilemma with Geotools, where reprojected color mapped rasters (thorugh SLD) result with borders having the lower color from the SLD rastersymbolizer. This is a big problem for many users, and we have to reproject the raster before serving it. It would be very important to be able to manage nodata values for out-of-border pixels, to be able to manage transparency and avoid those ugly borders... giovanni 2011/1/18 Marco Hugentobler <marco.hugentob...@sourcepole.ch> > > Agreed, int to double conversion could be optimal. > > oops, that should be 'Agreed, int to double conversion could be > problematic' > > Am Dienstag, 18. Januar 2011, um 09.19:23 schrieb Marco Hugentobler: > > > I thought that if data type of the source is integer the provider > > > could represent them as floating point. Byte can be represented as > > > integer. Bad solution however. > > > > Agreed, int to double conversion could be optimal. > > > > > > > This would be quite similar to your current approach, except that people > > will have the appropriate raster appearance if they don't use reproj. And > > if they do, they have an undesired border, but still the right colors in > > the raster area. > > > > Regards, > > Marco > > > > Am Montag, 17. Januar 2011, um 17.34:22 schrieb Radim Blazek: > > > On Mon, Jan 17, 2011 at 10:06 AM, Marco Hugentobler > > > <marco.hugentob...@sourcepole.ch> > Using NaN sounds like a good idea > > > and Qt has platform independent support for > > > > > > > it (qIsNan & co.). > > > > All other solutions I can think of seem to be more complicated (e.g. > > > > force a transparency value only if raster is reprojected). > > > > > > > >>float + NaN for byte/int? > > > >> > > > > This is not clear to me. Could you explain your approach for > byte/int? > > > > > > I thought that if data type of the source is integer the provider > > > could represent them as floating point. Byte can be represented as > > > integer. Bad solution however. > > > > > > Radim > > > -- > Dr. Marco Hugentobler > Sourcepole - Linux & Open Source Solutions > Churerstrasse 22, CH-8808 Pfäffikon SZ, Switzerland > marco.hugentob...@sourcepole.ch http://www.sourcepole.ch > Technical Advisor QGIS Project Steering Committee > _______________________________________________ > Qgis-developer mailing list > Qgis-developer@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/qgis-developer >
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