[R-sig-Geo] Datum/CRS for the worldHires map data

[Karl Ove Hufthammer]

On Fri, 8 Jan 2010 11:40:57 +0100 Karl Ove Hufthammer <karl at huftis.org> 
wrote:
> The reason is obviously that the worldHires map is not in the WGS 84 
> datum (which is reasonable, considering the age of the data). But which 
> datum is it in? I could find no information on this in the helpfile, or 
> on the referenced Web page? Does anybody on this list know, and perhaps 
> have a ready-made CRS strings I can use to project it?
> 
> Also, does there exist any other R map packages with maps of this 
> resolution (plain shoreline data without any additional metadata would 
> be OK), preferably with the maps actually included in the package, and 
> not downloading them from the Internet on demand?

Reading the ASDAR book (which I'm slowly working my way through), I 
discovered the 'Rgsshs' function in the 'maptools' package, which 
provides maps from the very nice Global Self-consistant Hierarchical 
High-resolution Shorelines database. The data have to be downloaded 
separately.

The data is in the WGS84, and does not suffer from the same problem as 
the worldHiresdata (even though it looks like parts of it is based on 
the same source).

My only issue with it is that using 'Rgshhs' is quite slow at the 
highest resolution, since, for example, selecting a tiny island in 
Norway will import the entire shoreline for the Eurasia continent, which 
is treated as one big polygon. Clipping this to the chosen xlim + ylim 
takes several minutes and much memory (as documented in the help file). 
Turning of clipping makes the import much faster, but it's still slow, 
and of course the resulting object takes up much memory (and uses a bit 
more time to render).

-- 
Karl Ove Hufthammer