[R-sig-Geo] suggestion for projection

[Alex Mandel]

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
http://spatialreference.org/ref/esri/102010/
South American Equidistant Conic
http://spatialreference.org/ref/esri/102032/

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.

Alex


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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