[R-sig-Geo] suggestion for projection

Alex Mandel tech_dev at wildintellect.com
Tue Apr 7 22:45:14 CEST 2009

I'm no expert here but I poked around spatialrefernce.org a bit and
found some stuff that might get you going in the right direction.

North American Equidistant Conic
South American Equidistant Conic

Any chance you could run the study using great circle distances, there
is support for such distance measuring in R using spDistsN1 in the sp
package. That way all you'd have to do is pick a spheroid to standardize on.


Kamran Safi wrote:
> Dear list,
> I am in search of a good projection with which I could run habitat
> utilization models on a continental scale. The projection I am looking
> for should preserve distances between points as good as possible and the
> map units should be meters. I think from what I have explored so far
> from the implementations of movement in habitat use models, preserving
> distance is the most important factor. Most solutions I found ready made
> were fine if you are working on a small scale of a few hectares or even
> a couple of square kilometers. The projection I am looking for should
> optimize "truth" in distances and be in meters (at least for the time
> being) for almost all of North-America and large stretches of
> South-America. I am aware that there is no single real solution out
> there for this large area, but there should be some projections with a
> minimal amount of error given the extent (so to speak an optimum). I
> quite often used spTransform, but never dealt with other things than
> longlat into moll or aitoff sometimes in utm and vice versa. I have no
> experience whatsoever with map units (and wouldn't know how to set or
> change them), as this wasn't an issue up to now, and only scratched the
> surface of oblique projections (sorry I am a biololgist in the first
> place trying to avoid making all too many mistakes in geography). I
> appreciate some expert opinion on this.
> The bbox (in longlat) of the area for which I am looking for a good
> projection is:    min   max
> x1 -127.2 -46.8
> x2  -19.7  48.6
> Many thanks in advance,
> Kami
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