[GRASS-user] gdal_translate

[Sandile Gumede]

Hi

Below is a step-by-step of what I have done but I'm getting an error when
running v.rast.stats vector=catchments raster=rainfall layer=1
colprefix=area.


GRASS 6.4.0RC5+39438 (SRTMDEM):~ > r.in.gdal
in=/home/tgumede1/grassdata/Cape_Town/TRMMLast1day.tif out=rainfall

Projection of input dataset and current location appear to match
 100%
r.in.gdal complete. Raster map <rainfall> created.
GRASS 6.4.0RC5+39438 (SRTMDEM):~ > g.region rast=rainfall -p
projection: 3 (Latitude-Longitude)
zone:       0
datum:      wgs84
ellipsoid:  wgs84
north:      33:30S
south:      33:45S
west:       18:15E
east:       19E
nsres:      0:15
ewres:      0:15
rows:       1
cols:       3
cells:      3
GRASS 6.4.0RC5+39438 (SRTMDEM):~ > r.in.gdal
in=/home/tgumede1/grassdata/Cape_Town/Dem_CF.tif out=dem target=SRTMDEM


Projection of input dataset and current location appear to match
 100%
r.in.gdal complete. Raster map <dem> created.
GRASS 6.4.0RC5+39438 (SRTMDEM):~ > g.region rast=dem -p
projection: 3 (Latitude-Longitude)
zone:       0
datum:      wgs84
ellipsoid:  wgs84
north:      33:40:46.499215S
south:      34:00:52.499215S
west:       18:17:55.500436E
east:       19:10:16.500436E
nsres:      0:00:03
ewres:      0:00:03
rows:       402
cols:       1047
cells:      420894
GRASS 6.4.0RC5+39438 (SRTMDEM):~ > r.watershed elevation=dem
accumulation=acc drainage=direction basin=catch stream=str threshold=200


SECTION 1a (of 5): Initiating Memory.
SECTION 1b (of 5): Determining Offmap Flow.
 100%
SECTION 2: A * Search.
 100%
SECTION 3: Accumulating Surface Flow.
 100%
SECTION 4: Watershed determination.
 100%
SECTION 5: Closing Maps.
 100%
GRASS 6.4.0RC5+39438 (SRTMDEM):~ > r.to.vect -s in=catch out=catchments
feature=area
Extracting areas...
 100%
 100%
Building topology for vector map <catchments>...
Registering primitives...
60653 primitives registered
314051 vertices registered
Building areas...
 100%
19885 areas built
1 isles built
Attaching islands...
 100%
Attaching centroids...
 100%
Number of nodes: 40769
Number of primitives: 60653
Number of points: 0
Number of lines: 0
Number of boundaries: 40768
Number of centroids: 19885
Number of areas: 19885
Number of isles: 1
r.to.vect complete.

GRASS 6.4.0RC5+39438 (SRTMDEM):~ > v.rast.stats vector=catchments
raster=rainfall layer=1 colprefix=precip

DBMI-DBF driver error:
SQL parser error: syntax error, unexpected NULL_VALUE processing 'NULL'
in statement:
UPDATE catchments SET precip_min=-NULL WHERE cat=10163
Error in db_execute_immediate()

ERROR: Error while executing: 'UPDATE catchments SET precip_min=-NULL WHERE
       cat=10163'



Here is the output of gdalinfo TRMMLast1day.tif

Origin = (18.250000000000000,-33.500000000000000)
Pixel Size = (0.250000000000000,-0.250000000000000)

-------------------- coordinates--------------------------------------------
Corner Coordinates:
Upper Left  (  18.2500000, -33.5000000)
Lower Left  (  18.2500000, -33.7500000)
Upper Right (  19.0000000, -33.5000000)
Lower Right (  19.0000000, -33.7500000)
Center      (  18.6250000, -33.6250000)


Here is what I did to clip the region of interest.

gdal_translate -a_srs EPSG:4326 -projwin 18.2987501 -33.6795831 19.1712501
-34.0141665 3B42RT.2010032900.1day.tif TRMMLast1day.tif


Is there something I have done wrong in these steps or there is something
wrong with my coordinates?



2010/7/6 <micha at arava.co.il>

> > Hi
> >
> > Is it wrong to use  -a_ullr option in gdal_translate to clip a small
> > portion
> > of the region from the big geotiff file region?
> >
>
> The option -a_ullr will change the georeference of the resulting file, so
> you could say it's "wrong" if you want to keep the original referencing.
> The way to clip a portion of the original and still maintain
> geo-referencing is with the -projwin option.
>
> --
> Micha
>
> > --
> > Kind Regards
> > TS Gumede
> > CSIR, Meraka Institute
> > 072 258 1650
> >
> > This mail was received via Mail-SeCure System.
> >
> >
> >
>
>


-- 
Kind Regards
TS Gumede
CSIR, Meraka Institute
072 258 1650
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