[GRASS-user] Re: v.rast.stats

Thu Jul 15 02:57:22 EDT 2010

Hi Micha

Which DEM data you used to test this rainfall data?

Can I have it?

On Sat, Jun 19, 2010 at 9:57 PM, Micha Silver <micha at arava.co.il> wrote:

>  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>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>
>>
>>>  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> 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 Silverhttp://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. +972-52-3665918http://surfaces.co.il
>
>

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