Have you checked the spatial stats task view on CRAN? http://cran.r-project.org/web/views/Spatial.html
-- Bert On Sun, Dec 30, 2012 at 6:49 PM, Tom Roche <tom_ro...@pobox.com> wrote: > > Is there packaged code to convert geographical coordinates (e.g., > longitude, latitude, elevation) to Cartesian coordinates in 3-space? > I can see how to do this using > > 1. a spherical-to-Cartesian conversion like pracma::sph2cart(tpr) > > http://cran.r-project.org/web/packages/pracma/ > > 2. a geographical-to-spherical conversion. This seems to involve (in > roughly increasing order of difficulty or error-prone-ness) > > * converting longitude (units=°) to an azimuthal angle (units=rad) > > * converting latitude (units=°) to a polar angle (aka inclination) > (units=rad) > > * converting elevation (usually, distance above mean sea level) to > radial distance (i.e., distance from earth center). Ideally this > should be done using a user-chosen coordinate reference system and > ellipsoid/geoid (i.e., PROJ.4-style), hence my hope that some package > (of which I'm currently unaware) has already coded this The Right Way. > For now, for the atmospheric model with which I need to work, I > believe I can just assume a spherical earth with r=6370 km, and just > add that to the elevation. > > 3. composition of the two (e.g., sph2cart(geo2sph(lat.lon.elev))), > noting that package=pracma uses the mathematics convention that > azimuth=Î and polar angle=Ï (vs the reverse physics convention). > > Net: the task seems straightforward enough, but there's certainly scope > for error, so I'd prefer to use tested, well-used code if available. > Am I missing something? > > TIA, Tom Roche <tom_ro...@pobox.com> > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm [[alternative HTML version deleted]]
______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
