R help - Dec 2012 - code to convert 3D geographical coordinates to Cartesian?

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=? and polar angle=? (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_Roche at pobox.com>

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_Roche@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=Θ and polar angle=φ (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_Roche@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

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https://stat.ethz.ch/pipermail/r-help/2012-December/332658.html
>> Is there packaged code to convert geographical coordinates (e.g.,
>> longitude, latitude, elevation) to Cartesian coordinates in 3-space?
...
>> 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.
https://stat.ethz.ch/pipermail/r-help/2012-December/332666.html
> Have you checked the spatial stats task view on CRAN?
> http://cran.r-project.org/web/views/Spatial.html
I have, and can't believe that functionality this fundamental is not
API. But I have looked at several packages and am not seeing it. I
suspect that either it's so low-level that it's just not exposed as API,
or just that there is API but I'm not seeing it in the package docs
("hidden in plain sight"). Hence I ask
>> Am I missing something?
TIA, Tom Roche <Tom_Roche at pobox.com>