On Thu, Apr 3, 2008 at 1:32 PM, Martin Desruisseaux <[EMAIL PROTECTED]> wrote: > Simone Giannecchini a écrit : > > > but still there can be some > > combinations for the RasterSymbolizer elements for which we can get > > images that have like 7 bands or images with just one band but with > > negative values. > > > > I see two distinct cases here: > > * Images with just one band (with or without negative values) are > usually backed by IndexColorModel. As long as the values stand > in no more than 16 bits, it can work even if there is negative > values (using complement-by-2 integer arithmetic). So in this > case it is not clear to me why we don't apply the color palette > associated with the image? >
I am not talking about raster with IndexColorModel, I should have probably pointed that out. Typical exmple would be elevation data, which is most part of the time store in rasters with single band of type short which cannot be visualized direclty. > * Images with more than 3 bands can be splitted in two case: > > a) They have a ColorModel (this is possible even if we have 7 bands, > provided that the guys who created the image was disciplined enough > for building a - maybe custom - ColorModel), in which case we should > be able to inspect the ColorModel in order to detect what seems closer > to gray, RGB or whatever bands. > > b) They have no ColorModel. This one is an open issue. But I wonder: do > we control the processing chain that produced the image, and if so can > we revisit it and try to figure out why they don't have a ColorModel, > instead than applying arbitrary choices? > Same above, if the image has a "nice color model" there are not so many problems, but for example I have some landsat geotiff coverages with 7 bands and it is not straightforward to decide which is the color model for them. Users should use raster symbolizer to pick out the RGB or Gray bands via the RasterSymbolizer but if they do not do that (this seems more like an error to me) we need to decide what to do (much like the visible band approach). It is not clear to me what you mean about the second part of the last paragraph, but here I am talking about doing some default manipulation of raster data which does not have intrinsic visualization info attached in the case where the users give us no clue how they want them to be rendered or the users gives us erroneous information. In such a case instead of throwing an error we should try to render something meaningful, much like openev, qgis or arcmap do. Simone. > > Martin > > -- ------------------------------------------------------- Eng. Simone Giannecchini President /CEO GeoSolutions S.A.S. Via Carignoni 51 55041 Camaiore (LU) Italy phone: +39 0584983027 fax: +39 0584983027 mob: +39 333 8128928 http://www.geo-solutions.it ------------------------------------------------------- ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
