[R-sig-Geo] spherical polygon

[Dylan Beaudette]

On Monday 08 February 2010, Karl Ove Hufthammer wrote:
> On Sun, 7 Feb 2010 17:30:23 -0800 Dylan Beaudette
>
> <dylan.beaudette at gmail.com> wrote:
> > How about an equal-area map projection?
> >
> > http://en.wikipedia.org/wiki/Map_projection#Equal-area
>
> Good idea. This will easily give you correct relative area measures,
> which will often be sufficient.
>
> But how to convert these into absolute measures, for example, the area
> in km²? Any known conversion factors for the equal-area projections
> available in 'spTransform'?

Most equal area map projections use meter as the linear unit of measure.

Cheers,
Dylan

-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341