Re: [GRASS-user] Change value of a specific raster cell

[Helmut Kudrnovsky]

>> east, north: 638546.314602, 222715.12161
>> myelev@user1:
>>  color: 255:255:255
>>  value: 160 

thats the result of my pixel change in the mapdisplay query.


> In the digitizer? I saw no widgets for coordinates there. 

there is no such widget.

my workflow mentioned above:

>> -> cell value: 160
>> -> digitize 1 point in your pixel of interest = click with the digitizer
>> into your pixel of interest
>> -> save raster map
>> -> quit raster digitizer

that's all



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Re: [GRASS-user] Change value of a specific raster cell

[Rich Shepard]

On Tue, 21 Feb 2017, Helmut Kudrnovsky wrote:


sorry, send button too early.


  :-)


what works for me:
goto/zoom to your pixel of interest.


  Using the GoTo on the status line, I presume.


east, north: 638546.314602, 222715.12161
myelev@user1:
 color: 255:255:255
 value: 160


  In the digitizer? I saw no widgets for coordinates there.

Thanks,

Rich
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Re: [GRASS-user] Change value of a specific raster cell

[Rich Shepard]

On Tue, 21 Feb 2017, Laurent C. wrote:


I would use v.in.ascii, v.to.rast and then r.patch.


Laurent,

  Thanks. That did the job.

Rich
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Re: [GRASS-user] Change value of a specific raster cell

[Helmut Kudrnovsky]

Rich Shepard wrote
>I tried this and must have missed a step. I selected 'raster
> digitizer',
> changed the status bar selector to 'Go to', entered the cell coordinates,
> and the value of 160.0 in the digitizer value combo box, and saved the
> map.
> r.what shows the original value, not the changed one.

sorry, send button too early.

what works for me:

goto/zoom to your pixel of interest.

raster digitizer -> select your raster what should be altered in one pixel
-> zoom to the pixel -> cell value: 160 -> digitize 1 point in your pixel of
interest -> save raster map -> quit raster digitizer

east, north: 638546.314602, 222715.12161
myelev@user1: 
  color: 255:255:255
  value: 160






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Re: [GRASS-user] Change value of a specific raster cell

[Helmut Kudrnovsky]

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Helmut
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Re: [GRASS-user] Change value of a specific raster cell

[Rich Shepard]

On Tue, 21 Feb 2017, Helmut Kudrnovsky wrote:


beside r.mapcalc, in the mapdisply there is the dropdown menu (2D view, 3D
view, vector digitizer, raster digitizer). with the raster digitizer you
can change the value of a single cell.


Helmut,

  I tried this and must have missed a step. I selected 'raster digitizer',
changed the status bar selector to 'Go to', entered the cell coordinates,
and the value of 160.0 in the digitizer value combo box, and saved the map.
r.what shows the original value, not the changed one.

Thanks for the suggestion,

Rich



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Re: [GRASS-user] Change value of a specific raster cell

[Helmut Kudrnovsky]

>What is the appropriate r.mapcalc command to change the value of the
>raster cell at a specified coordinate?

beside r.mapcalc, in the mapdisply there is the dropdown menue (2D view, 3D
view, vector digitizer, raster digitizer).

with the raster digitizer you can change the value of a single cell.



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Re: [GRASS-user] Change value of a specific raster cell

[Laurent C.]

Rich,

I would use v.in.ascii, v.to.rast and then r.patch.

Laurent

2017-02-21 13:42 GMT-06:00 Rich Shepard :
>   What is the appropriate r.mapcalc command to change the value of the
> raster cell at a specified coordinate? Cell resolution is 1m x 1m.
>
>   For a specified coordinate pair (east,north) I want to change the value
> from 158.7290 to 160.0. The expression would be 'value = 160.0', but needs
> to be applied to only a single cell.
>
>   Do I build a one-cell mask, change the value in the mask, then apply the
> mask's cell value to the whole map?
>
> Rich
>
>
>
>
>
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[GRASS-user] Change value of a specific raster cell

[Rich Shepard]

  What is the appropriate r.mapcalc command to change the value of the
raster cell at a specified coordinate? Cell resolution is 1m x 1m.

  For a specified coordinate pair (east,north) I want to change the value
from 158.7290 to 160.0. The expression would be 'value = 160.0', but needs
to be applied to only a single cell.

  Do I build a one-cell mask, change the value in the mask, then apply the
mask's cell value to the whole map?

Rich





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