Thanks Adrian. Will I find the test code in the GeoTools SVN?
I've been digging around some more and I think I'm on the right trail. The CRS.findMathTransform method led me to the CoordinateOperationFactory interface. I'm guessing that a Plug-In like the EPSG WKT Wiki mentioned in the Referencing Wiki implements this interface and actually contains the logic for the transformation. So I probably need to look there for the actual code in the CoordinateOperationFactory that generates the CoordinateOperation that is wrapped to the MathTransform and delivered to the CRS class. I hope I have this all correct. The Sunburned Surveyor P.S. - I'm wondering where I might find the code for the ESPG WKT Plug-In. I didn't see it in the referencing module of the SVN. On 9/4/07, Adrian Custer <[EMAIL PROTECTED]> wrote: > Look at the test code in the referencing module. That's undoubtedly the > best place to start. Martin is Mr. Referencing but he's busy enough that > he hides as much as he can afford to. > > --adrian > > > On Tue, 2007-09-04 at 16:15 -0700, Sunburned Surveyor wrote: > > Jody, > > > > I took a quick trip through the wiki for GeoTools Reprojection. It > > seems simple enough to use. > > > > However, I am one of those really sick people that needs to see how > > things work under the hood. Could you tell me where I would look in > > GeoTools to find out more about how the MathTransforms are calculated > > for the source and target CoordinateReferenceSystems. > > > > All I really know at this point is that you provide the GeoTools API > > with two ESPG codes and it "magically" returns a MathTransformation. > > > > What if I wanted to add support for a custom or new Map projection? > > What if there was a mistake in the generated MathTransformation that I > > wanted to fix? > > > > >From the perspective of a "potential" maintainer it would be good to > > know how things are working at a lower level. I'm fairly familiar with > > geodetic calculations, so I'm not really scared of this (yet). > > > > I wonder if any of the GeoTools developers can give me a brief (two or > > three minute) overview of how GeoTools gets from two (2) ESPG codes to > > a MathTransform object. If I can get this overview I'll dig into the > > Javadoc and source code for more details. > > > > SS > > > > Thanks for indulging my curiousity. > > > > On 9/4/07, Sunburned Surveyor <[EMAIL PROTECTED]> wrote: > > > We had talked a little the other day about a incorporating third-party > > > reprojection code into OpenJUMP. I sent a post to the UDig list, since > > > I know they support "on-the-fly" reprojection. > > > > > > I know we don't necessarily want to mess with "on-the-fly" > > > reprojection in OpenJUMP, but maybe we couls use the reprojection code > > > from UDig for a stand-alone utility or for a OpenJUMP plug-in. > > > > > > Jody Garnett put a section on the wiki for us that talks about this: > > > > > > http://docs.codehaus.org/display/GEOTDOC/Welcome+to+JUMP+Developers > > > > > > The Sunburned Surveyor > > > > > > > > > > > > ---------- Forwarded message ---------- > > > From: Sunburned Surveyor <[EMAIL PROTECTED]> > > > Date: Sep 4, 2007 3:27 PM > > > Subject: Re: [udig-devel] Transformation/Reprojection > > > To: User-friendly Desktop Internet GIS <[EMAIL PROTECTED]> > > > > > > > > > Jody wrote: "Since this question is asked every couple of months by a > > > jump developer it has made its way into the geotools user guide..." > > > > > > I really apologize about that. I'm sure that I'm the jackass that > > > keeps asking the same question. UDig, GeoTools, GeoAPI, Kosmo, SIGLE, > > > SkyJUMP, DeeJUMP... > > > > > > I have a hardtime keeping track of it all sometimes. Please be patient > > > with me. > > > > > > The section you added to the wiki will be very helpful. I will look it > > > over and will also forward this message to the JPP Developer List. > > > > > > Thanks for all of your help. I look forward to trying out UDig on my > > > GIS project. :] > > > > > > SS > > > > > > > > > On 9/4/07, Jody Garnett <[EMAIL PROTECTED]> wrote: > > > > Sunburned Surveyor wrote: > > > > > We were discussing options for reprojection/transformation code on the > > > > > OpenJUMP development list the other day. I know that UDig offers on > > > > > the fly reprojection, which is why I'm currently trying to download it > > > > > and get it running. > > > > > > > > > > I was curious, is the ,low-level reprojection code something UDig gets > > > > > from the GeoTools library, or is it code unique to UDig? Does the > > > > > low-level reprojection code work with GeoTools features, or does it > > > > > transform individual coordinates? Is it possible to access the API for > > > > > transformation of individual coordinates? > > > > > > > > > It is from the GeoTools library; you can use the "referencing module" > > > > with out depending on any GeoTools feature stuff. It is suitable for > > > > OpenJUMP etc... > > > > > > > > Since this question is asked every couple of months by a jump developer > > > > it has made its way into the geotools user guide: > > > > - http://docs.codehaus.org/display/GEOTDOC/Welcome+to+JUMP+Developers > > > > > It seems to me that it would make sense to share reporojection code > > > > > between OpenJUMP and UDig, especially if we can transform individual > > > > > coordinate and don't need to deal with the feature model problem. > > > > > > > > > Yes it makes sense to share; interfaces via geoapi and implementation > > > > via geotools, and hopfully swing widgets and swt widgets as well ;-) > > > > > > > > Don't worry about stealing worry about forking; if you see anything you > > > > want out of udig lets make sure we can place it in a common library so > > > > we can share maintence cost. > > > > > > > > Cheers, > > > > Jody > > > > _______________________________________________ > > > > User-friendly Desktop Internet GIS (uDig) > > > > http://udig.refractions.net > > > > http://lists.refractions.net/mailman/listinfo/udig-devel > > > > > > > > > > > ------------------------------------------------------------------------- > > This SF.net email is sponsored by: Splunk Inc. > > Still grepping through log files to find problems? Stop. > > Now Search log events and configuration files using AJAX and a browser. > > Download your FREE copy of Splunk now >> http://get.splunk.com/ > > _______________________________________________ > > Geotools-devel mailing list > > Geotools-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/geotools-devel > > ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Geotools-devel mailing list Geotools-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
