[GRASS-user] SRTM data, postgis and topographic maps

GRASS GRASS user
,
1

Hello Grass users,

I'm hoping to find somebody who understands SRTM data and wouldn't mind
sharing a few pointers.

I've downloaded various data sets, GTOPO30, SRTM30, SRTM3 and SRTM1 and
have tried to understand the various DEM formats (geotiff, DEM, binary
rasta etc)

Is it possible to import the data into a PostGIS database as data rather
then a BLOB? I was hoping there was coordinate/height data which I could
use.

My goal is to have grass generate a topo map given a specified
location/scale and perhaps have a crack at generating movie fly overs.
My Grass is compiled with FFmpeg.

Any pointers much appreciated.

Cheers
Bruce

2

Dnia czwartek, 4 stycznia 2007 18:15, Bruce Bushby napisał:

Hello Grass users,

I'm hoping to find somebody who understands SRTM data and wouldn't mind
sharing a few pointers.

I've downloaded various data sets, GTOPO30, SRTM30, SRTM3 and SRTM1 and

what you mean SRTM30?

have tried to understand the various DEM formats (geotiff, DEM, binary
rasta etc)

Is it possible to import the data into a PostGIS database as data rather
then a BLOB? I was hoping there was coordinate/height data which I could
use.

POSTGIS use geometric (vector) data formats like points or poligons not raster
data.
For my best knowlede:
- grass didn't support Postgis (yet) in write mode, i.e. grass cannot write
data to Postgis, QGIS can
- BLOB is type of mySQL rateher than PostgreSQL/Postgis and is used to large
binary text obiects, rather to rasters
-MS Acess, SQL Server and db2 (porbably oracle too) (with ArcGIS's
geodatabase) can store rasters in database tables
- Raster can be stored in postgreSQL databases, pixel by pixel (but not
directly from grass). This operation have very limited sense

My goal is to have grass generate a topo map given a specified
location/scale and perhaps have a crack at generating movie fly overs.

simply: use NVIZ

My Grass is compiled with FFmpeg.

Any pointers much appreciated.

Cheers
Bruce

In fact grass (with bash script, awk and the like) is very powerful programing
tool, you can do what you need without databases

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3

On Thursday 04 January 2007 09:15, Bruce Bushby wrote:

Hello Grass users,

I'm hoping to find somebody who understands SRTM data and wouldn't mind
sharing a few pointers.

I've downloaded various data sets, GTOPO30, SRTM30, SRTM3 and SRTM1 and
have tried to understand the various DEM formats (geotiff, DEM, binary
rasta etc)

Is it possible to import the data into a PostGIS database as data rather
then a BLOB? I was hoping there was coordinate/height data which I could
use.

Not currently, but ask on the postgis list for the most recent updates on
raster storage.

My goal is to have grass generate a topo map given a specified
location/scale and perhaps have a crack at generating movie fly overs.
My Grass is compiled with FFmpeg.

If this is your goal, then the route is fairly simple:

r.in.gdal in=yourfile out=dem
r.contour map=dem ...

or, if you would like slightly nicer output, use GMT for the contouring and
final map preparation. Here is one such example of overlaying contours on an
aerial photo:
http://169.237.35.250/~dylan/grass_user_group/map1.html

an image of simple contours with GMT can be found here:
http://169.237.35.250/~dylan/grass_user_group/elev.eps.png

For fly-overs try nviz

Any pointers much appreciated.

Cheers
Bruce

good luck!

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341