[Gvsig_english] raster iamge wrong band value

[Guillermo Tamburini]

hi,

in fact the descriptions of Vicent are more clear than mine... matters 
with the language (and the technical acknowledgment)!

Only one thing more. With the Sextante extension, you have the option of 
changing the datatype of the rasters. May be it could be useful for you.

Sextante->basic tools for rasater layers-> Change datatype

Then, if you change byte to integer (I have done it) I thing you will 
obtain the result that you want (the sea, in white, 210 instead -46).

But may be you will have one more problem... may be you will get out of 
bounds of ram memory. If you get that problem you could reduce the input 
data or change the memory settings.

And also I will check that there is not an error in the software 
(confusion in datatypes) which have to be solved (and say it to the 
developers). I will test a little bit the data you refer.

Regards.

Mithoefer, Klaus wrote:
> Thank you Guillermo and Vincent!
>
> I guess Vincent might be right. The data source I am using can be found on the web at ftp://guestglobcover:Pir8Eefo@us-ext-nas.eo.esa.int/regional/07_Globcover_200412_200606_V2.2_Africa.zip
> I use the file GLOBCOVER_200412_200606_V2.2_Africa_Reg.tif from this package which is an 8 bit unsigned file format. It seems really that gvSIG is interpreting this as 8 bit signed.
>
> I tried to convert is using GDAL to Eras IMG, but the effect remains.
>
> Thank you.
>
> Klaus
>
>
> -----Original Message-----
> From: gvsig_internacional-bounces at listserv.gva.es [mailto:gvsig_internacional-bounces at listserv.gva.es] On Behalf Of Guillermo Tamburini
> Sent: Wednesday, June 30, 2010 14:46
> To: Users and Developers mailing list
> Subject: Re: [Gvsig_english] raster iamge wrong band value
>
> hi,
>
> I have no idea what could be your problem. And i can not test with other 
> softwares because I haven't it now.
>
> Well, my only proposal is that you try to make sure that the different 
> software are understanding the data in the same data type. Raster layers 
> could be byte, float, integer... Or to export the data to other formats 
> for testing if the result is always the same.
>
>  From gvSIG you could check the data type in the general tab of the 
> layer proprieties. May be in ESRI and in that case you get only real 
> positive numbers, and gvSIG is understanding numbers up and down the 
> zero. In that case you would obtain the data moved a half to the 
> negative values.
>
> If you want you can send us some data example for testing it.
>
> Best regards.
>
> Mithoefer, Klaus wrote:
>   
>> Dear List,
>>
>> I use globecover vegetation data. When I try to retrieve the band value by using the information picker or assign values to a point layer I get the wrong value (e.g. for lakes I get-46 instead of 210). I compared this with ArcGIS and FWtools.
>>
>> I tried gvSIG 1.2, 1.9 and 2010 OADE with Geotif and Erdas IMG format. They all do the same. What is the problem?
>>
>> Thank you,
>>
>> Klaus
>>
>> Klaus Mithöfer 
>> Geographic Information Systems (GIS) Officer 
>> icipe - International Centre of Insect Physiology and Ecology 
>> P.O. Box 30772 - 00100 
>> Nairobi, Kenya 
>> Phone: +254-20-8632000, Extn. 2147
>> Fax: +254-20-8632001/2 
>> Mobile: +254-724-308404
>> E-Mail: kmithoefer at icipe.org
>> web: www.icipe.org
>>
>>
>> ----------------------------------------------------------------------------
>> This position is supported by German development cooperation // 
>> Centre for international Migration and Development - http://www.cimonline.de/en/index.asp
>>
>> Klaus.mithoefer at cimonline.de
>>
>>  
>> _______________________________________________
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>> Gvsig_internacional at listserv.gva.es
>> http://listserv.gva.es/cgi-bin/mailman/listinfo/gvsig_internacional
>>
>>
>>   
>>     
>
>
>   


-- 
Guillermo Tamburini Beliveau
Proyecto gvSIG 
Consellería de Infraestructuras y Transportes (GVA) 
Valencia (Spain) 
 

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