[GRASSLIST:6303] Re: California Albers and false northing

[Michael Barton]

Check out the Global Land Cover Facility
http://glcf.umiacs.umd.edu/index.shtml

You can download orthorectified landsat ETM data for anywhere in the world.
You can also download nice 30m SRTM data (90m outside the US) that you can
use for a base topographic layer. Both will import into GRASS using
r.in.gdal. They are in WGS84/UTM geotiff format. Once they are in grass, you
can r.proj to reproject them to nearly any other projection you might run
into. I just did this for one of my research areas today. I draped a band
7,5,2 rgb composite image over a 30m SRTM in NVIZ and it looked like we were
flying over it in a plane. Amazing.

Check out the VERY nice visual tutorial that comes with the current Mac OSX
binary release of GRASS.

Cheers,
Michael
____________________
C. Michael Barton, Professor of Anthropology
School of Human Evolution and Social Change
PO Box 872402
Arizona State University
Tempe, AZ  85287-2402
USA

Phone: 480-965-6262
Fax: 480-965-7671
www: <www.public.asu.edu/~cmbarton>


> From: Tim De Chant <dechant at nature.berkeley.edu>
> Date: Wed, 30 Mar 2005 14:30:35 -0800
> To: <GRASSLIST at baylor.edu>
> Subject: [GRASSLIST:6296] California Albers and false northing
> 
> I'm currently working on getting Landsat images for the Bay Area into
> GRASS 6.1cvs (Mac OS X) but I keep running into issues with the
> projection.  I've searched the list and came up with one solution,
> which was to manually edit the PROJ_INFO file into this:
> 
> name: Albers Equal Area
> proj: aea
> ellps: clark66
> a: 6378206.4000000004
> es: 0.0067686580
> lat_0: 0.0000000000
> lat_1: 34.0000000000
> lat_2: 40.5000000000
> lon_0: -120.0000000000
> y_0: -4000000
> 
> This returns an error saying the dataset PROJ_INFO doesn't match.
> Here's what the GeoTIFF contains:
> 
> name: Albers Equal Area
> proj: aea
> datum: nad83
> a: 6378137
> es: 0.0066943800
> lat_1: 34
> lat_2: 40.5
> lat_0: 0
> lon_0: -120
> x_0: 0
> y_0: -4000000
> no_defs: defined
> 
> I've tried modifying the PROJ_INFO file to match this to no avail.
> I've also tried to override the projection information in the dataset
> with no luck (under both variants of the PROJ_INFO file).
> 
> Does anyone have any advice for working with California Albers?  I'm a
> new user (so thanks for bearing with me).
> 
> Tim
> __________________________________________
> Tim De Chant
>      University of California, Berkeley
>      Environmental Science, Policy, and Management
>      137 Mulford Hall #3114
>      Berkeley, CA 94720-3114
>      (510) 643-3910