[GRASS-user] <sigh>Not this pest again!

Hi all,

It seems to be my burden lately to burden the list ...

... Having given up on the Australian Communications & Media Authority
DEM because it won't import into Grass-GIS (there seems to be some
fiddling to keep the DEM hidden behind a silly Windows app), I'm turning
to other DEMs.

The NASA SRTM seems as if it would suit my purposes, except that using
r.in.srtm I get a lovely image with no elevation data. So r.what comes
up with latitude, longitude, and null, eg:
150 | -34 | | *

QGIS imports and displays the HGT file okay, but misinterprets the
elevation data as band data (so for Katoomba, 1000m above sea level,
QGIS says the band is 1004).

There aren't that many options in r.in.srtm, so I don't think I could
have gotten any of them wrong...

Richard Chirgwin

Richard Chirgwin wrote:

... Having given up on the Australian Communications & Media Authority
DEM because it won't import into Grass-GIS (there seems to be some
fiddling to keep the DEM hidden behind a silly Windows app),

with the exact file size, expected rows & columns, and possibly byte info
and geographic extent known about it we still might be able to give some
guesses about how to get around that. Or is it known for sure that they've
taken steps to encrypt it?

I'm turning to other DEMs.

The NASA SRTM seems as if it would suit my purposes, except that using
r.in.srtm I get a lovely image with no elevation data. So r.what comes
up with latitude, longitude, and null, eg:
150 | -34 | | *

It probably worked, you just need to run g.region.

I just tried:
wget ftp://e0srp01u.ecs.nasa.gov/srtm/version2/SRTM3/Australia/S34E150.hgt.zip

r.in.srtm in=S34E150
r.info -r S34E150
min=-32
max=1360

g.region rast=S34E150
r.univar S34E150
..
..
..
d.mon x0
d.rast S34E150

r.fillnulls in=S34E150 out=S34E150.filled

and it all seemed to work ok.

Another way is get the data from Geoscience Australia's WMS server,

g.region n= s= w= e= res=...
r.in.wms -l -g mapserv="http://www.ga.gov.au/wms/getmap?dataset=national&&quot;

I imagine GA are much more GIS friendly than the media censors.

If you still have trouble with obtaining datasets, you might ask for help
on the OSGeo Aust-NZ mailing list.

QGIS imports and displays the HGT file okay, but misinterprets the
elevation data as band data (so for Katoomba, 1000m above
sea level, QGIS says the band is 1004).

no idea.

There aren't that many options in r.in.srtm, so I don't think I could
have gotten any of them wrong...

probably it worked ok you just have to adjust the zoom with g.region.

Hamish

Hamish wrote:

Richard Chirgwin wrote:
  

... Having given up on the Australian Communications & Media Authority
DEM because it won't import into Grass-GIS (there seems to be some
fiddling to keep the DEM hidden behind a silly Windows app),
    
with the exact file size, expected rows & columns, and possibly byte info
and geographic extent known about it we still might be able to give some
guesses about how to get around that. Or is it known for sure that they've
taken steps to encrypt it?
  

I will, perhaps, contact you offlist on that angle...

I'm turning to other DEMs.

The NASA SRTM seems as if it would suit my purposes, except that using
r.in.srtm I get a lovely image with no elevation data. So r.what comes
up with latitude, longitude, and null, eg:
150 | -34 | | *
    
It probably worked, you just need to run g.region.

I just tried:
wget ftp://e0srp01u.ecs.nasa.gov/srtm/version2/SRTM3/Australia/S34E150.hgt.zip

Eeek. Yes, you're right, I forgot to run g.region at the end of the
import. All is fine, and excuse the coming snip...

[snip]

Another way is get the data from Geoscience Australia's WMS server,
if you look in the capabilities XML file you will see that geotiff is conspicuously missing from the available image formats:
http://www.ga.gov.au/wms/getmap?dataset=national&request=capabilities

g.region n= s= w= e= res=...
r.in.wms -l -g mapserv="http://www.ga.gov.au/wms/getmap?dataset=national&&quot;

I imagine GA are much more GIS friendly than the media censors.
  

However, you may recall that the DEMs that GA served up weren't true
DEMs - from an earlier conversation:

if you look in the capabilities XML file you will see that geotiff is conspicuously missing from the available image formats:
http://www.ga.gov.au/wms/getmap?dataset=national&request=capabilities
  

(as you remarked to me back in April)

Cheers and thanks for tolerating the dummy...

Richard C

If you still have trouble with obtaining datasets, you might ask for help
on the OSGeo Aust-NZ mailing list.

QGIS imports and displays the HGT file okay, but misinterprets the
elevation data as band data (so for Katoomba, 1000m above
sea level, QGIS says the band is 1004).
    
no idea.

There aren't that many options in r.in.srtm, so I don't think I could
have gotten any of them wrong...
    
probably it worked ok you just have to adjust the zoom with g.region.

Hamish

Richard,

The NASA SRTM seems as if it would suit my purposes, except that using
r.in.srtm I get a lovely image with no elevation data. So r.what comes
up with latitude, longitude, and null, eg:
150 | -34 | | *

also consider the option to import ASCII SRTM data usign r.in.gdal in GRASS.
the projection is lat/long (WGS84, epsg id = 4326), while the elevation data are in meters.

Regards,

Marco