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

[Nicolas Cadieux]

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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