Michael, I agree with all you said. I guess my statement there was regarding a particular type of CoordinateOperation.
Paul Michaël Michaud wrote: > Paul Austin a écrit : > > >> Landon, >> >> Agreed each CoordinateOperation class should only know how to go in >> either the direction Geographics->ProjectedSystem or >> ProjectedSystem->Geographics. It should not need to know about any other >> systems. >> >> >> > Coordinate operations are not just Geographics->Projected and > Projected->Geographics. This is only the projection part (first and last > operation of Stefan's transformation chain). > Many operations involve a datum change. When you go from a local datum > to wgs84 for example, you must consider that the new coordinate system > has another origin, another orientation, and the ellipsoid you will use > to calculate lon and lat has another shape ! This transformation has no > common point with a projection, but most people do not differentiate > both operations. > If you want to apply the pivot principle, you have to say : each > CoordinateReferenceSystem has to know how to go from and to Geocentric > WGS84, but again, it may be much calculations for cases where only one > local datum is involved. > > Michael > > >> Paul >> >> Sunburned Surveyor wrote: >> >> >> >>> Paul wrote: "My vision for end user code. >>> >>> JtsTransform transform = >>> JtsTransformFactory.createCoordinateConversion(3005, 26910);" >>> >>> I like it! >>> >>> My concerns are about how the layer underneath this works. I think a >>> system where the steps necessary for the transformation are left to >>> the implementer of a projection and not the code provided with the "to >>> and from" spatial reference systems is the best. >>> >>> Here is another way of saying it: In an ideal system the code >>> performing the actual transformation should have no idea of what the >>> eventual destination spatial reference system is. It should only need >>> to know how to get a coordinate from itself to the pivot spatial >>> reference system. >>> >>> SS >>> >>> On 9/10/07, Paul Austin <[EMAIL PROTECTED]> wrote: >>> >>> >>> >>> >>>> Landon, >>>> >>>> My vision for end user code. >>>> >>>> JtsTransform transform = >>>> JtsTransformFactory.createCoordinateConversion(3005, 26910); >>>> >>>> Paul >>>> >>>> ------------------------------------------------------------------------- >>>> This SF.net email is sponsored by: Microsoft >>>> Defy all challenges. Microsoft(R) Visual Studio 2005. >>>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >>>> _______________________________________________ >>>> Jump-pilot-devel mailing list >>>> Jump-pilot-devel@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >>>> >>>> >>>> >>>> >>>> >>> ------------------------------------------------------------------------- >>> This SF.net email is sponsored by: Microsoft >>> Defy all challenges. Microsoft(R) Visual Studio 2005. >>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >>> _______________________________________________ >>> Jump-pilot-devel mailing list >>> Jump-pilot-devel@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >>> >>> >>> >>> >> ------------------------------------------------------------------------- >> This SF.net email is sponsored by: Microsoft >> Defy all challenges. Microsoft(R) Visual Studio 2005. >> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ >> _______________________________________________ >> Jump-pilot-devel mailing list >> Jump-pilot-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >> >> >> >> >> > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2005. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Jump-pilot-devel mailing list > Jump-pilot-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel > ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
