[GRASS-user] importing dem files: projection details?

[Markus Neteler]

hi Tyler,

On Sun, Mar 14, 2010 at 7:19 AM, Tyler Smith <tyler.smith at eku.edu> wrote:
> Hi,
>
> It's been a while since I used GRASS, and I'm having trouble getting my data
> into the system. The data I'm working on is available here:
>
> http://kymartian.ky.gov/demwebusgs/har/index.html
>
> It's USGS format DEM data. The meta data is found here:
>
> http://kymartian.ky.gov/demwebusgs/DEM_dem.xml
>
> Apparently, the metadata is not available in the data files, so I had to
> enter the details by hand in setting up a new location. I'm working from
> Neteler and Mitasova 3rd ed., but otherwise have very limited GIS
> background. My attempt at the projection is listed below. It appears that
> I'm using two different systems here, with the actual raster file in units
> of meters, while the default region is measured in degrees. I'm not sure how
> to convert the easting/northing into degrees, or the degrees into meters.
> I've also tried this with State Plane System and Lat-Long, but haven't
> figured out what I'm doing wrong. Please help!

The rule is that you can have only one projection in a location.
If you have several projections you need several locations and
to reproject data between them (r.proj, v.proj).

GRASS can generate locations directly from metadata.

Cheers
Markus

> Thanks,
>
> Tyler
>
>
> -PROJ_INFO-------------------------------------------------
> name       : Lambert Conformal Conic
> datum      : nad83
> nadgrids   : TN
> proj       : lcc
> ellps      : grs80
> a          : 6378137.0000000000
> es         : 0.0066943800
> f          : 298.2572221010
> lat_0      : 36.3333333300
> lat_1      : 38.6666666670
> lat_2      : 37.0833333330
> lon_0      : -85.7500000000
> x_0        : 1500000.0000000000
> y_0        : 1000000.0000000000
> -PROJ_UNITS------------------------------------------------
> unit       : meter
> units      : meters
> meters     : 1.0
>
>
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