Ciao Oleg,
I have done a minor modification to the statistics operations and now
it should be possible to get the locations of max and min values from
the Extrema GeoTools operation.
Please, note that the Extrema and Histogram operations are mere
wrappers of the JAI operations with the same name. Hence you can
refere to them for most information.
The only real addition, is made by the fact that you can specify a ROI
as a JTS polygon in the same CRS as the source coverage.
Let me know how it goes.
Simone.
On Sat, Sep 27, 2008 at 7:18 PM, Oleg72 <[EMAIL PROTECTED]> wrote:
>
> Ciao Simone
> Thank you very much for your answer.
> Is there way to get a location of the min value?
>
>
> Simone.Giannecchini wrote:
>>
>> Ciao Oleg,
>> please red below...
>>
>> On Tue, Sep 9, 2008 at 10:40 AM, Oleg72 <[EMAIL PROTECTED]> wrote:
>>
>>>
>>> Dear All,
>>> I am trying to obtain a minimum value from an ASCII Grid. Unfortunately I
>>> am
>>> getting a nodata value instead.
>>> I tried 2 ways:
>>> - category.get(1).getRange().getMinimum(), and
>>> - gridcoverage.getProperty("minimum") (based on Extrema operation)
>>> both methods return -9999.0 (which is nodata value) but the real min
>>> value
>>> is about 700
>>
>>
>>
>> First observation. As noted before the category mechanism will not give
>> you
>> the min value.
>> The best way to solve your problem would be as follow:
>>
>> 1> Get the NODATA value (check for the nodata category)
>> 2a> if NODATA is NAN (as in grass ascii grids) extrema should give you the
>> min
>> 2b> if NODATA is not NAN ( as in esri ascii grids) histogram would be you
>> friend as long as the NODATA is outside the valid range of your data. You
>> can use histogram to get statistics only a specifi range of you dynamic.
>> Of course I am open to suggestions for improving the usability of the
>> arcgrid plugin.
>>
>> Hope that helps.
>> Ciao,
>> Simone.
>>
>>
>>
>>>
>>>
>>> The complete code I used:
>>>
>>> File file = new File("raster.asc");
>>> ArcGridReader reader = new ArcGridReader(file);
>>> gc = (GridCoverage2D) reader.read(null);
>>> System.out.println("min VALUE: "
>>> +gc.getSampleDimension(0).getCategories().get(1).getRange().getMinimum());
>>>
>>> op= new OperationJAI("Extrema");
>>> ParameterValueGroup params = op.getParameters();
>>> params.parameter("Source").setValue(gc);
>>> gc=(GridCoverage2D)op.doOperation(params,null);
>>> System.out.println("Grid Minimum
>>> "+((double[])gc.getProperty("minimum"))[0]);
>>>
>>> Thank you very much in advance,
>>> Oleg
>>>
>>> --
>>> View this message in context:
>>> http://www.nabble.com/ASCII-Grid-min-value-tp19388244p19388244.html
>>> Sent from the geotools-gt2-users mailing list archive at Nabble.com.
>>>
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>>
>>
>>
>> --
>> -------------------------------------------------------
>> Eng. Simone Giannecchini
>> GeoSolutions S.A.S.
>> Owner - Software Engineer
>> Via Carignoni 51
>> 55041 Camaiore (LU)
>> Italy
>>
>> phone: +39 0584983027
>> fax: +39 0584983027
>> mob: +39 333 8128928
>>
>>
>> http://www.geo-solutions.it
>> http://www.geo-solutions.it/simone.giannecchini
>>
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>
> --
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> http://www.nabble.com/ASCII-Grid-min-value-tp19388244p19704650.html
> Sent from the geotools-gt2-users mailing list archive at Nabble.com.
>
>
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--
-------------------------------------------------------
Eng. Simone Giannecchini
GeoSolutions S.A.S.
Owner - Software Engineer
Via Carignoni 51
55041 Camaiore (LU)
Italy
phone: +39 0584983027
fax: +39 0584983027
mob: +39 333 8128928
http://www.geo-solutions.it
http://www.geo-solutions.it/simone.giannecchini
http://www.linkedin.com/in/simonegiannecchini
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