[GRASSLIST:5924] newbie trying to get started with a USGS DEM

GRASS GRASS user
,
1

I am working with Debian/unstable's GRASS 6.0.0beta2. I've looked at
the tutuorials, but they don't give much guidance on how to display
USGS DEMs, in particular since the DEM files themselves seem to be
somewhat opaque. I get lots of mismatches, particularly since I don't
know what I am doing. For example, I try:

I've imported the DEM, e.g.:

  $ r.in.gdal input=A145121.DEM output=A145121

which seemed to go okay. Then:

  $ nviz elevation=A145121
  Error: Raster A145121@russell is outside of current region
  Load Failed.

Guidance appreciated.

--
Russell Senior ``I have nine fingers; you have ten.''
seniorr@aracnet.com

2

I am working with Debian/unstable's GRASS 6.0.0beta2. I've looked at
the tutuorials, but they don't give much guidance on how to display
USGS DEMs, in particular since the DEM files themselves seem to be
somewhat opaque. I get lots of mismatches, particularly since I don't
know what I am doing. For example, I try:

I've imported the DEM, e.g.:

  $ r.in.gdal input=A145121.DEM output=A145121

which seemed to go okay. Then:

  $ nviz elevation=A145121
  Error: Raster A145121@russell is outside of current region
  Load Failed.

Guidance appreciated.

Zoom to the geographic extents of your map before trying to display them:

g.region rast=A145121

also, it might be better to start with a simpler 2D view before trying NVIZ.

d.mon x0
d.rast A145121

Hamish

3

"Hamish" == Hamish <hamish_nospam@yahoo.com> writes:

Hamish> Zoom to the geographic extents of your map before trying to
Hamish> display them:

Hamish> g.region rast=A145121

Hamish> also, it might be better to start with a simpler 2D view
Hamish> before trying NVIZ.

Hamish> d.mon x0
Hamish> d.rast A145121

Excellent! Thank you, that's got me off to a start. The DEMs are in
7.5-minute chunks. When I try to combine them, e.g.:

  $ g.region rast=C645121,D645121
  $ nviz elevation=C645121,D645121

There is a small gap between the two rasters. How can I stitch them
together? Also, is there an easy way to draw on a long/lat grid so
that I can orient myself more easily?

Thanks!

--
Russell Senior ``I have nine fingers; you have ten.''
seniorr@aracnet.com

4

try r.patch, and v.mkgrid

-Ian

On Feb 27, 2005, at 10:31 PM, Russell Senior wrote:

"Hamish" == Hamish <hamish_nospam@yahoo.com> writes:

Hamish> Zoom to the geographic extents of your map before trying to
Hamish> display them:

Hamish> g.region rast=A145121

Hamish> also, it might be better to start with a simpler 2D view
Hamish> before trying NVIZ.

Hamish> d.mon x0
Hamish> d.rast A145121

Excellent! Thank you, that's got me off to a start. The DEMs are in
7.5-minute chunks. When I try to combine them, e.g.:

  $ g.region rast=C645121,D645121
  $ nviz elevation=C645121,D645121

There is a small gap between the two rasters. How can I stitch them
together? Also, is there an easy way to draw on a long/lat grid so
that I can orient myself more easily?

Thanks!

--
Russell Senior ``I have nine fingers; you have ten.''
seniorr@aracnet.com