kriging - too long time

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Tomas Lanczos

kriging - too long time

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I am performing some kriging following the procedure as it is here:
http://casoilresource.lawr.ucdavis.edu/drupal/node/438

My problem is that the kriging proces is very slow, it takes approx. 7
hours. Is the problem a too high resolution, or too much sampling points
(2234)? How can I optimalize the process?

My region setup is the following:

projection: 1 (UTM)
zone:       33
datum:      ** unknown (default: WGS84) **
ellipsoid:  bessel
north:      5387295.0553002
south:      5288130.42061478
west:       652025.98376024
east:       786301.92841404
nsres:      150.02214022
ewres:      150.02898844
rows:       661
cols:       895
cells:      591595

Many thanks

Tomas

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Edzer J. Pebesma-2

Re: kriging - too long time

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Perhaps add nmax = 50 to the krige step -- use kriging in a local
neighbourhood.
--
Edzer

Tomas Lanczos wrote:

> I am performing some kriging following the procedure as it is here:
> http://casoilresource.lawr.ucdavis.edu/drupal/node/438
>
> My problem is that the kriging proces is very slow, it takes approx. 7
> hours. Is the problem a too high resolution, or too much sampling
> points (2234)? How can I optimalize the process?
>
> My region setup is the following:
>
> projection: 1 (UTM)
> zone:       33
> datum:      ** unknown (default: WGS84) **
> ellipsoid:  bessel
> north:      5387295.0553002
> south:      5288130.42061478
> west:       652025.98376024
> east:       786301.92841404
> nsres:      150.02214022
> ewres:      150.02898844
> rows:       661
> cols:       895
> cells:      591595
>
> Many thanks
>
> Tomas
>
> _______________________________________________
> statsgrass mailing list
> [hidden email]
> http://grass.itc.it/mailman/listinfo/statsgrass

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Carlos Grohmann-2

Re: kriging - too long time

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In reply to this post by Tomas Lanczos
Tomas,

nmax has a strong influence on kriging time. In some tests I've done,
interpolation time for and area with 520 rows x 430 cols ranged from
about 20 seconds for nmax=8 up to 20 HOURS for nmax =399.

best

Carlos




On 9/2/07, Tomas Lanczos <[hidden email]> wrote:

> I am performing some kriging following the procedure as it is here:
> http://casoilresource.lawr.ucdavis.edu/drupal/node/438
>
> My problem is that the kriging proces is very slow, it takes approx. 7
> hours. Is the problem a too high resolution, or too much sampling points
> (2234)? How can I optimalize the process?
>
> My region setup is the following:
>
> projection: 1 (UTM)
> zone:       33
> datum:      ** unknown (default: WGS84) **
> ellipsoid:  bessel
> north:      5387295.0553002
> south:      5288130.42061478
> west:       652025.98376024
> east:       786301.92841404
> nsres:      150.02214022
> ewres:      150.02898844
> rows:       661
> cols:       895
> cells:      591595
>
> Many thanks
>
> Tomas
>
> _______________________________________________
> statsgrass mailing list
> [hidden email]
> http://grass.itc.it/mailman/listinfo/statsgrass
>


--
+-----------------------------------------------------------+
              Carlos Henrique Grohmann - Guano
  Visiting Researcher at Kingston University London - UK
  Geologist M.Sc  - Doctorate Student at IGc-USP - Brazil
Linux User #89721  - carlos dot grohmann at gmail dot com
+-----------------------------------------------------------+
_________________
"Good morning, doctors. I have taken the liberty of removing Windows
95 from my hard drive."
--The winning entry in a "What were HAL's first words" contest judged
by 2001: A SPACE ODYSSEY creator Arthur C. Clarke

Can't stop the signal.

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Edzer J. Pebesma-2

Re: kriging - too long time

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That might be "explained" as follows: 8 to 400 is a factor 25, solving a
covariance matrix is an O(N^2) operation so would slow down by a factor
25*25 = 625. The remaining factor 6 (seconds to hours: 3600/625) should
be attributable to the load of finding the nearest 400 neighbours
instead of 8 nearest neighbours. I don't know that behaviour (a
bucket-PR quadtree search index is used), but am not surprised.

Best wishes,
--
Edzer

Carlos "Guâno" Grohmann wrote:

> Tomas,
>
> nmax has a strong influence on kriging time. In some tests I've done,
> interpolation time for and area with 520 rows x 430 cols ranged from
> about 20 seconds for nmax=8 up to 20 HOURS for nmax =399.
>
> best
>
> Carlos
>
>
>
>
> On 9/2/07, Tomas Lanczos <[hidden email]> wrote:
>  
>> I am performing some kriging following the procedure as it is here:
>> http://casoilresource.lawr.ucdavis.edu/drupal/node/438
>>
>> My problem is that the kriging proces is very slow, it takes approx. 7
>> hours. Is the problem a too high resolution, or too much sampling points
>> (2234)? How can I optimalize the process?
>>
>> My region setup is the following:
>>
>> projection: 1 (UTM)
>> zone:       33
>> datum:      ** unknown (default: WGS84) **
>> ellipsoid:  bessel
>> north:      5387295.0553002
>> south:      5288130.42061478
>> west:       652025.98376024
>> east:       786301.92841404
>> nsres:      150.02214022
>> ewres:      150.02898844
>> rows:       661
>> cols:       895
>> cells:      591595
>>
>> Many thanks
>>
>> Tomas
>>
>> _______________________________________________
>> statsgrass mailing list
>> [hidden email]
>> http://grass.itc.it/mailman/listinfo/statsgrass
>>
>>    
>
>
>  

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