There is a bunch of factories for this stuff:
http://docs.geotools.org/latest/userguide/library/referencing/internal.html
I am used to handling this as a geometry processing task in other systems
(rather than a math transform)....
i.e. use either a process or a function that geometry in and a DEM in, and
"Drapes" the geometry over the DEM returning a new geometry.
- http://docs.geotools.org/latest/userguide/tutorial/function.html
- http://docs.geotools.org/latest/userguide/tutorial/process.html
Those are worth going over anyways as they introduce how geotools factories
work.
--
Jody Garnett
On Wed, Jun 18, 2014 at 4:06 AM, Eric W. Anderson <ander...@cs.cmu.edu>
wrote:
> What would I have to do to add this? Or, put slightly differently, what's
> the
> current process by which findMathTransform() looks for conversions, and
> how can
> I tell it about a new one?
>
> (I know I could just hack in some code to do what I want, but that would be
> ugly.)
>
> Thanks,
> Eric
>
> Thus spake Andrea Aime (andrea.a...@geo-solutions.it):
>
> > On Fri, Jun 13, 2014 at 10:36 PM, Eric W. Anderson
> > <[1]ander...@cs.cmu.edu> wrote:
> >
> > Hi All,
> >
> > I'm using Geotools, and I need to convert coordinates between 2D
> and 3D
> > coordinate reference systems. I recognize that there's no
> > universally-correct way to do this: 2D -> 3D means "making up" a Z
> > coordinate, and 3D -> 2D means losing information. But, is there
> some
> > way to teach Geotools that, in my particular context, I want to use
> a
> > specific transformation. E.g.:
> >
> > +-----+ +-----+
> > | | --- Z = 15 ---> | |
> > | 2D | | 3D |
> > | | <-- drop Z ---- | |
> > +-----+ +-----+
> > I know I can transform any particular coordinate manually this way,
> but
> > I'd like to integrate it so this Just Works. e.g. I can do
> > CRS.findMathTranform(a, b) and if a is convertible to my 2D CRS,
> and my
> > 3D CRS is convertible to b, it works.
> >
> > No. The 3D -> 2D path is normally supported, but the 2D -> 3D never
> is as
> > far as I remember.
> > That said, if all you want is adding an extra static ordinate, it
> should
> > not be too hard to do it yourself.
> > I guess it could be interesting to have some tooling in geotools that
> > given a 2D geometry and a helper object, would add the 3rd ordinate,
> where
> > the helper might look like:
> > interface ElevationProvider() {
> > double getElevation(DirectPosition2D pos);
> > }
> > which then the client would implement in different ways, e.g., fixed
> > value, or DEM sampling.
> > As usual, it's a matter of one having enough time/funding to discuss
> the
> > evolution in the dev mailing list,
> > implement it, and merge it.
> > Cheers
> > Andrea
> >
> > --
> > ==
> > GeoServer Professional Services from the experts! Visit
> > [2]http://goo.gl/NWWaa2 for more information.
> > ==
> > Ing. Andrea Aime
> > @geowolf
> > Technical Lead
> > GeoSolutions S.A.S.
> > Via Poggio alle Viti 1187
> > 55054 Massarosa (LU)
> > Italy
> > phone: +39 0584 962313
> > fax: +39 0584 1660272
> > mob: +39 339 8844549
> > [3]http://www.geo-solutions.it
> > [4]http://twitter.com/geosolutions_it
> > -------------------------------------------------------
> >
> > References
> >
> > Visible links
> > 1. mailto:ander...@cs.cmu.edu
> > 2. http://goo.gl/NWWaa2
> > 3. http://www.geo-solutions.it/
> > 4. http://twitter.com/geosolutions_it
>
> --
> Eric W. Anderson Computer Science Department
> ander...@cs.cmu.edu Carnegie Mellon University
> phone: +1-412-268-1908 Gates-Hillmann Center 6005
>
> PGP key fingerprint:
> D3C5 D6FF EDED 9F1F C36D 53A3 74B7 53A6 3C74 5F12
>
>
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