[GRASS-user] Re: v.rast.stats
Micha Silver
micha at arava.co.il
Sat Jun 19 15:57:48 EDT 2010
Hello Sandile:
I tried to duplicate your steps and it seems to work for me.
Here's what I did:
wget ftp://trmmopen.gsfc.nasa.gov/pub/gis/3B42RT.2010032900.1day.tif
wget ftp://trmmopen.gsfc.nasa.gov/pub/gis/3B42RT.2010032900.1day.tfw
gdalinfo 3B42RT.2010032900.1day.tif
Driver: GTiff/GeoTIFF
Files: 3B42RT.2010032900.1day.tif
3B42RT.2010032900.1day.tfw
Size is 1440, 480
Coordinate System is `'
Origin = (-180.000000000000000,60.000000000000000)
Pixel Size = (0.250000000000000,-0.250000000000000)
....
---- Note: no projection info above ----
---- Now I use the -projwin option of gdal_translate to select a small
window
gdal_translate -a_srs EPSG:4326 -projwin 34.0 33.0 36.0 29.0
3B42RT.2010032900.1day.tif rainfall_il.tif
---- GEOGCS entry now shows 4326 ----
g.mapset map=ASTER_DEM loc=WGS84
----- A location setup as EPSG:4326----
r.in.gdal israel.tif out=rainfall_il
r.univar rainfall_il
100%
total null and non-null cells: 77760000
total null cells: 0
Of the non-null cells:
----------------------
n: 77760000
minimum: 0
maximum: 34
range: 34
mean: 0.364583
mean of absolute values: 0.364583
standard deviation: 3.45241
variance: 11.9192
variation coefficient: 946.948 %
sum: 28350000
----- Now using an existing catchment vector map ----
v.rast.stats vect=arava_wsheds rast=rainfall_il colpre=precip
v.info -c arava_wsheds
Displaying column types/names for database connection of layer 1:
INTEGER|cat
CHARACTER|label
DOUBLE PRECISION|area_km
INTEGER|precip_n
DOUBLE PRECISION|precip_min
DOUBLE PRECISION|precip_max
DOUBLE PRECISION|precip_range
DOUBLE PRECISION|precip_mean
DOUBLE PRECISION|precip_stddev
DOUBLE PRECISION|precip_variance
DOUBLE PRECISION|precip_cf_var
DOUBLE PRECISION|precip_sum
---- and some values ----
v.db.select arava_wsheds
cat|label|area_km|precip_n|precip_min|precip_max|precip_range|precip_mean|precip_stddev|precip_variance|precip_cf_var|precip_sum
21|Jordan|1055.231692|2|0|0|0|0|0|0||0
19|Hidan|987.811979|2|0|0|0|0|0|0||0
28|Og|124.122969|||||||||
36|Zarqa|273.606213|||||||||
24|Kidron|122.460114|||||||||
9|Darga|289.012122|||||||||
6|Arugot|236.365116|1|0|0|0|0|0|0||0
26|Mujib|1277.546513|2|0|0|0|0|0|0||0
---- (Many catchments have 0 or no value because of the small region I
chose. The global data is 1/4 degree resolution and my region is only 2
deg E-W.)----
HTH...
--
Micha
On 06/17/2010 12:50 PM, Sandile Gumede wrote:
> Hi
>
> It is still giving me -NULL value error.
>
> Do you think maybe its the way I downloaded my rainfall data? This is
> the site where I downloaded my data sets_
> ftp://trmmopen.gsfc.nasa.gov/pub/gis/ _and this data covers the whole
> world, the only thing I did was to clip a specific region (using
> coordinates) that is in South Africa to do my analysis. I used a bash
> script to download and project the data, see below:
>
>
> #!/bin/bash
>
> wget ftp://trmmopen.gsfc.nasa.gov/pub/gis/3B42RT.2010032900.1day.tif
> wget ftp://trmmopen.gsfc.nasa.gov/pub/gis/3B42RT.2010032900.1day.tfw
>
> gdal_translate -of GTiff -co "PROFILE=GeoTIFF" -co "INTERLEAVE=PIXEL"
> -co "COMPRESS=LZW" -co "TILED=YES" -a_srs EPSG:4326 -a_ullr 18.2987501
> -33.6795831 19.1712501 -34.3487498 3B42RT.2010032900.1day.tif
> TRMMLast1day.tif
>
>
>
>
> On Thu, Jun 17, 2010 at 8:41 AM, Sandile Gumede <akasandile at gmail.com
> <mailto:akasandile at gmail.com>> wrote:
>
> Hi
>
> It is still giving me -NULL value error.
>
> Do you think maybe its the way I downloaded my rainfall data? This
> is the site where I downloaded my data sets_
> ftp://trmmopen.gsfc.nasa.gov/pub/gis/ _and this data covers the
> whole world, the only thing I did was to clip a specific region
> (using coordinates) that is in South Africa to do my analysis. I
> used a bash script to download and project the data, see below:
>
>
> #!/bin/bash
>
> wget ftp://trmmopen.gsfc.nasa.gov/pub/gis/3B42RT.2010032900.1day.tif
> wget ftp://trmmopen.gsfc.nasa.gov/pub/gis/3B42RT.2010032900.1day.tfw
>
> gdal_translate -of GTiff -co "PROFILE=GeoTIFF" -co
> "INTERLEAVE=PIXEL" -co "COMPRESS=LZW" -co "TILED=YES" -a_srs
> EPSG:4326 -a_ullr 18.2987501 -33.6795831 19.1712501 -34.3487498
> 3B42RT.2010032900.1day.tif TRMMLast1day.tif
>
>
>
> 2010/6/15 Micha Silver <micha at arava.co.il <mailto:micha at arava.co.il>>
>
> On 15/06/2010 14:35, Sandile Gumede wrote:
>> Hi
>> If I run g.region rast=rainfall -p, I get:
> OK, what you've done here is change the current region to
> match the raster "rainfall".
> Can you now try:
> v.rast.stats -c vect=catchments rast=rainfall pref=precip
>
>
>>
>> projection: 3 (Latitude-Longitude)
>> zone: 0
>> datum: wgs84
>> ellipsoid: wgs84
>> north: 33:40:46.49916S
>> south: 34:20:55.49928S
>> west: 18:17:55.50036E
>> east: 19:10:16.50036E
>> nsres: 0:00:05.01875
>> ewres: 0:00:02.18125
>> rows: 480
>> cols: 1440
>> cells: 691200
>>
>> and If I run r.univar rainfall, I get the following output:
>>
>> 100%
>> total null and non-null cells: 691200
>> total null cells: 0
>>
>> Of the non-null cells:
>> ----------------------
>> n: 691200
>> minimum: 0
>> maximum: 3094
>> range: 3094
>> mean: 22.0228
>> mean of absolute values: 22.0228
>> standard deviation: 76.1639
>> variance: 5800.94
>> variation coefficient: 345.841 %
>> sum: 15222164
>>
>>
>>
>> On Tue, Jun 15, 2010 at 12:22 PM, Hamish <hamish_b at yahoo.com
>> <mailto:hamish_b at yahoo.com>> wrote:
>>
>> Micha wrote:
>> > The only unusual thing I notice above is that the
>> resolution settings
>> > for the raster are different N-S and E-W. This came
>> from the original
>> > tiff (see below) which also has rectangular pixels,
>>
>> that is perfectly normal for a lat/lon map away from the
>> equator.
>> longitude scales a cos(lat).
>>
>>
>> > (the v.rast.stats module creates a temp raster at the
>> *current region's
>> > resolution* settings, which might be different from
>> this rainfall
>> > raster's rectangular resolution...)
>>
>> the results of:
>>
>> g.region -p rast=mapname
>> r.univar mapname
>>
>>
>> could help.
>>
>>
>> Hamish
>>
>>
>>
>>
>>
>>
>> --
>> Kind Regards
>> TS Gumede
>> CSIR, Meraka Institute
>> 072 258 1650
>>
>>
>> This mail was received via Mail-SeCure System.
>
>
> --
> Micha Silver
> http://www.surfaces.co.il/
> Arava Development Co. +972-52-3665918
>
>
>
>
>
> --
> Kind Regards
> TS Gumede
> CSIR, Meraka Institute
> 072 258 1650
>
>
>
>
> --
> Kind Regards
> TS Gumede
> CSIR, Meraka Institute
> 072 258 1650
>
>
> This mail was received via Mail-SeCure System.
--
Micha Silver
Arava Development Co. +972-52-3665918
http://surfaces.co.il
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