[Qgis-user] raster with distance values from a point

[Kirk Schmidt]

To add to Nicolas" comment:

1) Create your point layer from a csv (easting, northing id) as a minimum

2) If you want to stay with process modeler, use the SAGA>Raster 
creation tools> Rasterize Algorithm to convert the point layer to your 
required resolution and size

3) Use the  GDAL>Raster Analysis>Proximity or SAGA>Raster tools> 
Proximity Raster  to create your output.

Kirk Schmidt

On 2/25/2021 4:24 PM, Nicolas Cadieux wrote:
>
> Hi,
>
> You can cut down you use of several plugins by doing the following,
>
> 1) Create a vector point file with a single point having the numerical 
> field containing the value 1.  This file could be a csv containing WKT.
>
> 2) Use the vector to raster conversion.  (This will take your vector 
> point file, an create a raster of x,y dimensions.  You point will 
> become 1 and all other values will be 0.
>
> 3) Use the Proximity raster distance gdal function.
>
> This requires no plugins so it should be easy to create a graphical 
> modeler.  My favorite way would be to go to strait Python and to call 
> the gdal proximity function from my Python script.  If you had hundred 
> or thousands of these to do, I could develop a Python script that 
> could automate the entire thing. Contact me if you have questions.
>
> Nicolas Cadieux
>
>
> On 2021-02-25 12:58 p.m., Fabio Falchi wrote:
>>
>> Dear all,
>>
>> not having received any answer, I repeat the request.
>> I need to speed up the process of obtaining rasters with distances 
>> from a single point (or a single lat-lon coordinate) in it. Manually 
>> I use this procedure:
>> With a georeferenced raster in a UTM projection I use raster 
>> calculator to obtain a raster with all pixels set to zero. Then, with 
>> Serval plug-in, I manually set to 1 the value of the pixel in the 
>> wanted position (either by using a satellite overlay or by using a 
>> point vector layer with the appropriate coordinates). Then I use the 
>> proximity function under Raster>Analisys menu.
>> I want to make this via the Graphical Modeler, in order to be able to 
>> make the process fast and skip the manual introduction with Serval 
>> plug-in. At the very least, I need a mode to put the value 1 in the 
>> pixel of the selected null raster in the position givel by lat-lon 
>> coordinates.
>> Thank you!
>> Best,
>> Fabio Falchi
>>
>> /USC - Universidade de Santiago de Compostela/
>>
>> /ISTIL - Light Pollution Science and Technology Institute/
>>
>>
>> Il sabato 20 febbraio 2021, 18:04:14 CET, Fabio Falchi 
>> <fabio_falchi at yahoo.it> ha scritto:
>>
>>
>> Dear all,
>>
>> I need to speed up the process of obtaining rasters with distances 
>> from a single point in it. Manually I use this procedure:
>> With a georeferenced raster in a UTM projection I use raster 
>> calculator to obtain a raster with all pixels set to zero. Then, with 
>> Serval plug-in, I manually set to 1 the value of the pixel in the 
>> wanted position (either by using a satellite overlay or by using a 
>> point vector layer with the appropriate coordinates). Then I use the 
>> proximity function under Raster>Analisys menu.
>> I want to make this via the Graphical Modeler, in order to be able to 
>> make the process fast and skip the manual introduction with Serval 
>> plug-in. At the very least, I need a mode to put the value 1 in the 
>> pixel of the selected null raster in the position givel by lat-lon 
>> coordinates.
>> Thank you!
>> Best,
>> Fabio Falchi
>>
>> /USC - Universidade de Santiago de Compostela/
>>
>> /ISTIL - Light Pollution Science and Technology Institute/
>>
>>
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> -- 
> Nicolas Cadieux
> https://gitlab.com/njacadieux
>
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-- 
Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email: kirk at nortekresources.com
Web: www.nortekresources.com

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