[R] Accurate area map projections

[White.Denis@epamail.epa.gov]

Just catching up on r-help, ignore if you have already have moved on ...

I almost always use the Lambert azimuthal equal-area projection (called
"azequalarea" in the maps package).  Unless the study area is unusually
elongated this projection will give good performance.  In fact, it has
lower average distortion (but not lower extreme distortion) than the
standard projection used for the conterminous US, the Albers conical
equal-area.  See:  Kimerling AJ, Overton WS, White D. 1995. Statistical
comparison of map projection distortions within irregular
areas. Cartography and Geographic Information Systems 22(3):205-221,
(pdf available at http://www.epa.gov/wed/pages/staff/white/pubs.htm)

Denis White
   US EPA, 200 SW 35th St, Corvallis, Oregon, 97333 USA
   voice: 541.754.4476, email: white.denis at epa.gov
   web: www.epa.gov/wed/pages/staff/white/

> Hi,
> Could any one point me to the projection, and parameters if necessary,
that
> would show each country/continent with it's area accurately refelcted
on the
> plot? E.g. aitoff vs. albers vs. bonne vs. cylequalearea vs. guyou -
they
> don't all look the same to mee but some of the documentations suggests
they
> are equal area?  Of course this isn't my field, so I am largely
guessing and
> am prorbably making some naive assumptions :)
> I'm pretty sure this is on the R-help archive but I don't seem to be
able to
> access most of the posts that the search returns - I keep getting a
'file
> not found' page...
> TIA
> Mark