[R-sig-Geo] Good projection for N/S America?

[Tim Keitt]

Thanks. My application is not that demanding. Really, I just want it
to look reasonable. My plan is to lay out the postings in the
projected coordinates and then back transform into geographic
coordinates for analysis. I tried lots of projections and found
Lamberts Azimuthal Equal Area to be quite good. I like the look of the
Azimuthal Equidistant better, but figured equal area was a good
choice.

THK

On 4/4/07, White.Denis at epamail.epa.gov <White.Denis at epamail.epa.gov> wrote:
> Tim,
>
> It depends on which kind of distortion is of most concern.  For many
> types of extensive data, especially counts, for example, the equal area
> property is desirable.  We used the Lambert cylindrical equal area
> projection with standard parallels of +/- 30 degrees for some western
> hemispherical work, see reference below.  (The center longitude could be
> -80 west, but that is less important than the choice of parallels.)
>
> Before falling back on the Lambert as an easy to use projection, I tried
> to get several ESRI products to implement an interrupted projection
> using the sinusoidal projection, in part for reasons given in the second
> reference.  I used a separate center longitude for north and south of
> the equator and the appearance is certainly more satisfactory than the
> Lambert in my opinion.  I'll attach a PDF of an illustration of this
> approach generated in R that I hope you will get but not the rest of the
> list unfortunately.  I can send PDFs of the references also if needed.
>
> Denis
>
> Lawler JJ, White D, Neilson RP, Blaustein AR.  2006.  Predicting
> climate-induced range shifts: model differences and model reliability.
> Global Change Biology 12:1568-1584.
>
> White D.  2006.  Display of pixel loss and replication in reprojecting
> raster data from the sinusoidal projection.  Geocarto International
> 21(2):19-22.
>
> (See attached file: whemi.sinus.pdf)
>
> r-sig-geo-bounces at stat.math.ethz.ch wrote on 2007-04-04 12:17:39:
>
> > Anyone know of a particularly good map projection for showing all of
> > North and South America without too much distortion?
> >
> > THK
> >
> > --
> > Timothy H. Keitt, University of Texas at Austin
> > Contact info and schedule at http://www.keittlab.org/tkeitt/
> > Reprints at http://www.keittlab.org/tkeitt/papers/
> > ODF attachment? See http://www.openoffice.org/
> >
> > _______________________________________________
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> > R-sig-Geo at stat.math.ethz.ch
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>


-- 
Timothy H. Keitt, University of Texas at Austin
Contact info and schedule at http://www.keittlab.org/tkeitt/
Reprints at http://www.keittlab.org/tkeitt/papers/
ODF attachment? See http://www.openoffice.org/