R help - Jul 2009 - Map projections - converting latitude/longitude to eastings and northings

I am trying to set up a Grass project and need to set up the region so
that I can view the map.  I can look at a map and find the lat/lon,
but the map projection is in UTM NAD38 WGS84 and I need to set the
eastings and northings.  Is there a package that will help me
calculate this in R.
thanks

-- 
Stephen Sefick

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

								-K. Mullis

Wouldn't grass-users, or maybe R-sig-geo be a more appropriate list? Given
points in geographical coordinates, use project() or spTransform() in rgdal.
The former will not do datum transformation, the latter will. NAD83 is a US
datum specification based on WGS84, UTM is a projection but is useless
without the zone number. If you can find the datum of your input data:

in_crs <- CRS("+proj=longlat +datum=<whatever>")
out_crs <- CRS("+proj=utm +zone=<#> +datum=NAD83
+ellps=WGS84")
utm_bbox <- bbox(spTransform(SpatialPoints(ll_crds, proj4string=in_crs),
out_crs)

will get from one matrix of coordinates to the other. Note that for obvious
reasons a rectangle on one side will only rarely be a rectangle on the
other, so I've just taken a bounding box.

Roger Bivand


stephen sefick wrote:
> 
> I am trying to set up a Grass project and need to set up the region so
> that I can view the map.  I can look at a map and find the lat/lon,
> but the map projection is in UTM NAD38 WGS84 and I need to set the
> eastings and northings.  Is there a package that will help me
> calculate this in R.
> thanks
> 
> -- 
> Stephen Sefick
> 
> 
> 
> 
-- 
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