[GRASS-user] v.rast.stats
Sandile Gumede
akasandile at gmail.com
Wed Jul 14 10:38:45 EDT 2010
Hi,
Can anyone help!
On Wed, Jul 14, 2010 at 1:31 PM, Sandile Gumede <akasandile at gmail.com>wrote:
> Hi,
>
> I'm using GTOPO30 DEM data and TRMM (rainfall) data, I selected the data
> for the whole of africa but I'm getting an error when executing
> v.rast.stats.
>
> Here is a step-by-step of what I did:
>
> 1. GTOPO30 DEM
> - downloaded e020n10,w020s10,e020n40,w020n40 compressed files from "
> ftp://edcftp.cr.usgs.gov/pub/data/gtopo30/global/".
> - decompressed all the above files.
> - Added "PIXELTYPE SIGNEDINT" in all .HDR files
> - warp merged all the .DEM file with "gdalwarp *.DEM Africa.tif"
> command.
> - projected it with "gdal_translate -a_srs EPSG:4326 Africa.tif
> DEM.tif"
>
> 2. TRMM "rainfall" data
> - downloaded 3B42RT.2010061503.1day.tif,3B42RT.2010061503.1day.tfw
> from "".
> - projected it with "gdal_translate -a_srs EPSG:4326 -projwin -20 40
> 60 -60 3B42RT.2010061503.1day.tif TRMM.tif ".
>
> Then, imported the two data sets:
>
> r.in.gdal in=/home/tgumede1/grassdem/ict4eo/DEM.tif out=dem
>
> Projection of input dataset and current location appear to match
> 100%
> r.in.gdal complete. Raster map <dem> created.
>
> g.region rast=dem
>
> r.in.gdal in=/home/tgumede1/grassdem/ict4eo/CapeTown_TRMMs.tif out=rainfall
> target=CapeTown
>
> Projection of input dataset and current location appear to match
> 100%
> r.in.gdal complete. Raster map <rainfall> created.
>
> r.watershed elevation=dem accumulation=acc drainage=direction stream=str
> basin=catch memory=300 threshold=100000
>
> 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%
>
> Q: How do one really know the exact threshold value?
>
> r.to.vect in=catch out=catchments feature=area
>
> Extracting areas...
> 100%
> 100%
> Building topology for vector map <catchments>...
> Registering primitives...
> 134246 primitives registered
> 701002 vertices registered
> Building areas...
> 100%
> 44645 areas built
>
> 1 isles built
> Attaching islands...
> 100%
> Attaching centroids...
> 100%
> Number of nodes: 89602
> Number of primitives: 134246
>
> Number of points: 0
> Number of lines: 0
> Number of boundaries: 89604
> Number of centroids: 44642
> Number of areas: 44645
> Number of isles: 1
> Number of areas without centroid: 3
> r.to.vect complete.
>
>
> g.region rast=rainfall
>
> v.rast.stats vector=catchments raster=rainfall colprefix=precip
> WARNING: Area without centroid (may be OK for island)
> WARNING: Area without centroid (may be OK for island)
> WARNING: Area without centroid (may be OK for island)
>
> DBMI-DBF driver error:
> SQL parser error: syntax error, unexpected NULL_VALUE processing 'NULL'
> in statement:
> UPDATE catchments SET precip_cf_=-NULL WHERE cat=17
>
> Error in db_execute_immediate()
>
> ERROR: Error while executing: 'UPDATE catchments SET precip_cf_=-NULL WHERE
> cat=17'
>
>
> - output of r.info -g
>
> r.info -g rainfall
> north=40
> south=-60
> east=60
> west=-20
>
> - output of v.info
>
> v.info -g catchments
> north=40
> south=-60
> east=60
> west=-20
>
> top=0.000000
> bottom=0.000000
>
> output of r.info
>
> Type of Map: raster Number of Categories: 2559
> Data Type:
> CELL
> Rows:
> 400
> Columns:
> 320
> Total Cells:
> 128000
> Projection:
> Latitude-Longitude
> N: 40N S: 60S Res:
> 0:15
> E: 60E W: 20W Res:
> 0:15
> Range of data: min = 0 max =
> 2559
>
>
> Data
> Description:
> generated by
> r.in.gdal
>
>
>
> Comments:
> r.in.gdal input="/home/tgumede1/grassdem/ict4eo/CapeTown_TRMMs.tif"
> \
> output="rainfall" target="CapeTown"
>
>
> - output of r.univar
>
> r.univar rainfall
> 100%
> total null and non-null cells: 115200000
>
> total null cells: 0
>
> Of the non-null cells:
> ----------------------
> n: 115200000
> minimum: 0
> maximum: 2559
> range: 2559
> mean: 22.4897
> mean of absolute values: 22.4897
> standard deviation: 83.1312
> variance: 6910.79
> variation coefficient: 369.642 %
> sum: 2590809300
>
>
>
>
>
>
> --
> Kind Regards
> TS Gumede
> CSIR, Meraka Institute
> 072 258 1650
>
>
--
Kind Regards
TS Gumede
CSIR, Meraka Institute
072 258 1650
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