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? 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