<br><br>output of <a href="http://v.info">v.info</a> catchments, see below:<br><br> <br>Type of Map: vector (level: 2) <br> <br>
Number of points: 0 Number of areas: 2273 <br> Number of lines: 0 Number of islands: 1 <br> Number of boundaries: 4928 Number of faces: 0 <br>
Number of centroids: 2273 Number of kernels: 0 <br> <br> Map is 3D: No <br>
Number of dblinks: 1 <br> <br> Projection: Latitude-Longitude <br>
N: 33:40:46.499215S S: 34:00:52.499215S <br> E: 19:10:16.500436E W: 18:17:55.500436E <br> <br>
Digitization threshold: 0 <br> Comments: <br><br><br>output of <a href="http://r.info">r.info</a>, see below:<br><br>Type of Map: raster Number of Categories: 232 <br>
Data Type: CELL <br> Rows: 1 <br> Columns: 3 <br>
Total Cells: 3 <br> Projection: Latitude-Longitude <br> N: 33:30S S: 33:45S Res: 0:15 <br>
E: 19E W: 18:15E Res: 0:15 <br> Range of data: min = 0 max = 232 <br> <br>
Data Description: <br> generated by r.in.gdal <br><br> <br>GRASS 6.4.0RC6 (SRTMDEM):~ > v.extract catchments out=catch_691 where="cat=691"<br>1 categories loaded from table <catchments><br>
Extracting features...<br>Building topology for vector map <catch_691>...<br>Registering primitives...<br>237 primitives registered<br>804 vertices registered<br>Building areas...<br> 100%<br>1 areas built<br>1 isles built<br>
Attaching islands...<br> 100%<br>Attaching centroids...<br> 100%<br>Number of nodes: 237<br>Number of primitives: 237<br>Number of points: 0<br>Number of lines: 0<br>Number of boundaries: 236<br>Number of centroids: 1<br>
Number of areas: 1<br>Number of isles: 1<br>Writing attributes...<br>v.extract complete.<br><br>GRASS 6.4.0RC6 (SRTMDEM):~ > g.region rast=rainfall<br><br>GRASS 6.4.0RC6 (SRTMDEM):~ > d.rast rainfall<br> 100%<br>GRASS 6.4.0RC6 (SRTMDEM):~ > d.vect catch_691<br>
The bounding box of the map is outside the current region, nothing drawn.<br><br><br>Now, do you think this would ever work out?<br><br>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<br>
<br><br><br> <br> <br><br><br><br><div class="gmail_quote">On Thu, Jul 22, 2010 at 9:42 PM, Micha Silver <span dir="ltr"><<a href="mailto:micha@arava.co.il">micha@arava.co.il</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"><div class="im">
On 07/22/2010 10:55 AM, Sandile Gumede wrote:
</div><div class="im"><blockquote type="cite">Hi<br>
How do you remove null cells, I guess that is what's causing the
problem.<br>
</blockquote></div><div class="im">
Sandile:<br>
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.<br>
<blockquote type="cite"><br>
r.to.vect complete.<br>
</blockquote>
I guess this step is your conversion of basins to a polygon vector map?
How many polygons are you getting? Check with <a href="http://v.info" target="_blank">v.info</a>. What size are
they? <br>
v.db.addcol catchments col="area_sqm double precision"<br>
v.to.db catchments opt=area col=area_sqm units=me<br>
<br>
And please remind us of the resolution of the rainfall raster with:<br>
<a href="http://r.info" target="_blank">r.info</a> rainfall <br>
</div><blockquote type="cite">GRASS 6.4.0svn (SRTMDEM):~ > r.univar rainfall 100%<div class="im"><br>
total null and non-null cells: 12967201<br>
total null cells: 7202<br>
<br>
Of the non-null cells:<br>
----------------------<br>
n: 12959999<br>
minimum: 0<br>
maximum: 36<br>
range: 36<br>
mean: 4.99965<br>
mean of absolute values: 4.99965<br>
standard deviation: 9.57207<br>
variance: 91.6246<br>
variation coefficient: 191.455 %<br>
sum: 64795464<br>
<br>
GRASS 6.4.0svn (SRTMDEM):~ > v.rast.stats vect=catchments
rast=rainfall colprefix=precip<br>
Processing data (16 categories)...<br>
Updating the database ...<br>
DBMI-DBF driver error:<br>
SQL parser error: syntax error processing 'NULL'<br>
in statement:<br>
UPDATE catchments SET precip_cf_=-NULL WHERE cat=10728<br>
Error in db_execute_immediate()<br>
<br>
ERROR: Error while executing: 'UPDATE catchments SET precip_cf_=-NULL
WHERE<br>
cat=10728'<br>
<br clear="all">
<br>
</div></blockquote><div class="im">
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? <br>
# extract<br>
v.extract catchments out=catch_10728 where="cat=10728"<br>
# Display<br>
g.region rast=rainfall<br>
d.rast rainfall<br>
d.vect catch_10728<br>
<br>
-- <br>
cheers,<br>
Micha<br>
</div><blockquote type="cite">-- <br><div class="im">
Kind Regards<br>
TS Gumede<br>
CSIR, Meraka Institute<br>
072 258 1650<br>
<br>
<br></div><div class="im">
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</pre>
</blockquote><div class="im">
<br>
<br>
<pre cols="72">--
Micha Silver
Arava Development Co. +972-52-3665918
<a href="http://surfaces.co.il" target="_blank">http://surfaces.co.il</a>
</pre>
</div></div>
</blockquote></div><br><br clear="all"><br>-- <br>Kind Regards<br>TS Gumede<br>CSIR, Meraka Institute<br>072 258 1650<br><br>