output of v.info catchments, see below:
Type of Map: vector (level: 2)
Number of points: 0 Number of areas: 2273
Number of lines: 0 Number of islands: 1
Number of boundaries: 4928 Number of faces: 0
Number of centroids: 2273 Number of kernels: 0
Map is 3D: No
Number of dblinks: 1
Projection: Latitude-Longitude
N: 33:40:46.499215S S: 34:00:52.499215S
E: 19:10:16.500436E W: 18:17:55.500436E
Digitization threshold: 0
Comments:
output of r.info, see below:
Type of Map: raster Number of Categories: 232
Data Type: CELL
Rows: 1
Columns: 3
Total Cells: 3
Projection: Latitude-Longitude
N: 33:30S S: 33:45S Res: 0:15
E: 19E W: 18:15E Res: 0:15
Range of data: min = 0 max = 232
Data Description:
generated by r.in.gdal
GRASS 6.4.0RC6 (SRTMDEM):~ > v.extract catchments out=catch_691 where=“cat=691”
1 categories loaded from table
Extracting features…
Building topology for vector map <catch_691>…
Registering primitives…
237 primitives registered
804 vertices registered
Building areas…
100%
1 areas built
1 isles built
Attaching islands…
100%
Attaching centroids…
100%
Number of nodes: 237
Number of primitives: 237
Number of points: 0
Number of lines: 0
Number of boundaries: 236
Number of centroids: 1
Number of areas: 1
Number of isles: 1
Writing attributes…
v.extract complete.
GRASS 6.4.0RC6 (SRTMDEM):~ > g.region rast=rainfall
GRASS 6.4.0RC6 (SRTMDEM):~ > d.rast rainfall
100%
GRASS 6.4.0RC6 (SRTMDEM):~ > d.vect catch_691
The bounding box of the map is outside the current region, nothing drawn.
Now, do you think this would ever work out?
Can the Aster_Dem work with this rainfall (TRMM ) data? Can also the resolution of raster (Aster and TRMM) maps be a problem? If yes, I know how to download it, I would only need the projection steps
On Thu, Jul 22, 2010 at 9:42 PM, Micha Silver <micha@arava.co.il> wrote:
On 07/22/2010 10:55 AM, Sandile Gumede wrote:
Hi
How do you remove null cells, I guess that is what’s causing the problem.
Sandile:
If I remember your project details, I think that the problem is not the null cells in your rainfall data, but rather the very small catchment polygons, some of which fall totally within a single rainfall cell which has a null value.
r.to.vect complete.
I guess this step is your conversion of basins to a polygon vector map? How many polygons are you getting? Check with v.info. What size are they?
v.db.addcol catchments col=“area_sqm double precision”
v.to.db catchments opt=area col=area_sqm units=me
And please remind us of the resolution of the rainfall raster with:
r.info rainfall
GRASS 6.4.0svn (SRTMDEM):~ > r.univar rainfall 100%
total null and non-null cells: 12967201
total null cells: 7202
Of the non-null cells:
n: 12959999
minimum: 0
maximum: 36
range: 36
mean: 4.99965
mean of absolute values: 4.99965
standard deviation: 9.57207
variance: 91.6246
variation coefficient: 191.455 %
sum: 64795464
GRASS 6.4.0svn (SRTMDEM):~ > v.rast.stats vect=catchments rast=rainfall colprefix=precip
Processing data (16 categories)…
Updating the database …
DBMI-DBF driver error:
SQL parser error: syntax error processing ‘NULL’
in statement:
UPDATE catchments SET precip_cf_=-NULL WHERE cat=10728
Error in db_execute_immediate()
ERROR: Error while executing: ‘UPDATE catchments SET precip_cf_=-NULL WHERE
cat=10728’
Another suggestion: One of the catchment polygons that is failing above has cat value 10728. How about extracting just that single polygon, then display it on a map together with the rainfall raster to see where it falls?
extract
v.extract catchments out=catch_10728 where=“cat=10728”
Display
g.region rast=rainfall
d.rast rainfall
d.vect catch_10728
–
cheers,
Micha
–
Kind Regards
TS Gumede
CSIR, Meraka Institute
072 258 1650
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Micha Silver
Arava Development Co. +972-52-3665918
[http://surfaces.co.il](http://surfaces.co.il)
–
Kind Regards
TS Gumede
CSIR, Meraka Institute
072 258 1650