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List:       grass-user
Subject:    Re: [GRASS-user] how to query a raster value
From:       王德辉 <dehuiw () gig ! ac ! cn>
Date:       2012-11-28 7:37:10
Message-ID: 7cb85b.13c15.13b45f2ae2f.Coremail.dehuiw () gig ! ac ! cn
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It means the point value of the active raster layer is nodata(null). Please notice that only the active raster (left clicking the layer on the Map layers menu and it turning back ) can be queried when you use  query button. For example, if you added "lakes"and "elevation" raster layers (nc_spm dataset) and your active layer is lakes,but you want query the elevation by using the gui qurey button and you cilck the point outside the lakes, then the valu would be * .
May could help you!
dehui

在2012-11-28 06:15:58,王德辉<dehuiw@gig.ac.cn>写道：
> On Tue, Nov 27, 2012 at 4:21 PM, 侯伟 <houw11@lzu.edu.cn> wrote:
> >
> > in map display has a query button, i want to query a image value in a point
> > but get the below:
> >
> > 489701.0583783784|4273345.954594594||*|
> >
> > no value are displayed.  i think in grass there are category and cell can be
> > rater, does above are one type of this.
> 
> To me it looks as if the position is in a NO DATA area ("*").
> 
> > how can i change the type and query the value?
> 
> Please double check the coordinates.
> 
> Markus
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