[R-sig-Geo] requesting 3D spTransform()

[Tom Roche]

https://stat.ethz.ch/pipermail/r-sig-geo/2012-December/017099.html
>> Is there packaged code to convert geographical coordinates (e.g.,
>> longitude, latitude, elevation) to Cartesian coordinates in 3-space?

https://stat.ethz.ch/pipermail/r-sig-geo/2013-January/017110.html
> [In] the C code underlying spTransform(), you'll see that the call to
> pj_transform() sets z to zero, that is to the datum surface, and the
> returned values are discarded.

ISTM "The Better Way" would be to add a boolean argument: e.g.,
spTransform(..., 3d=false, ...)

* make the current behavior the default
* for 3d=true, don't discard the elevations

Am I missing something?

> The most robust route forward might be to permit 3D SpatialPoints to
> be transformed directly, and choose a geo-centric target projection.

Is there a way to request this? I note package=sp allows FRs

https://r-forge.r-project.org/tracker/?atid=4032&group_id=1014&func=browse

but I'm not seeing equivalent UI for package=rgdal.

TIA, Tom Roche <Tom_Roche at pobox.com>