Bryce L Nordgren wrote: > > I did a preliminary overview. I think it works this way: > > + RasterSymbolizer really doesn't do anything other than hold data for the > properties defined by SLD. It's just a data structure. > + There's a renderer implemented specifically for Grid Coverage 2Ds which > interprets these settings (like any colormaps, etc.) and produces a > portrayed image. > > I have to verify this (gotta run out the door soon), but I would bet that > it requires a GridCoverage2D because it knows it's backed by Java 2D > graphics objects. (e.g., Raster, SampleModel, ColorModel, etc.) No one > actually "extracts" data from a coverage to portray it, they just make a > ColorModel and blammo, Bob's your uncle. > I came to a similar conclusion - see separate email. > If we make a different coverage implementation backed by Multiarray2, we're > going to have a different rendering process (or an adapter to GridCoverage2D). > Perhaps a processing chain that results in something RasterSymbolizer can use (unless someone can sweet talk OGC into some funding). >> So for my question; if not using Expression how do you extract values >> from a coverage? >> > According to 19123: Coverage.evaluate(DirectPosition) will return a tuple > of values valid at a specific location. Coverage.list() returns a Set of > all of the Domain-Range associations in the coverage. > Coverage.select(GM_Object, TM_Period) subsets a coverage. > Coverage.find(DirectPosition) returns a list of Domain-Range associations > in order of increasing distance from the supplied point. > Coverage.evaluateInverse(Record) will return a Set of DomainObjects > (positions/geometries) which are associated with matching values in the > Range. > > In the OGC model? Dunno. > Agreed; cool well now we are in the clear then. >> Yes it does, you can use xpath to grab out values: ie VALUES[12] or >> VALUES[X] or [EMAIL PROTECTED] VALUES[X*43+Y]. Of course if a coverage is >> defined by an operation then raster symbolizer must have a way to let us >> get at that information .... >> > I think RasterSymbolizer just needs to hold information about how data > should be portrayed. The renderer needs to get at the data (or use some > library which can.) > I did expect to see something; aka for each channel I expected to see expression working against that tuple you get back from the ISO Coverage.
Cheers and thanks for taking the time on this. Jody ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
