[Qgis-user] consultation (Juan Pablo Moreno Sebastian)

Wed Jun 21 18:19:48 PDT 2023

Hi Juan,
That sounds like it might be what this GRASS addon does: r.prominence -
GRASS GIS manual (osgeo.org)
<https://grass.osgeo.org/grass82/manuals/addons/r.prominence.html>
Does it do what you intend your plugin to do?  This discussion might also
help: Re: [GRASS-user] r.prominence (mail-archive.com)
<https://www.mail-archive.com/grass-user@lists.osgeo.org/msg11209.html>

QGIS includes GRASS GIS and a processing provider allowing us to run GRASS
modules in QGIS, so if that does what you want, you should probably look at
writing an algorithm description for the QGIS processing provider to be
able to use it.  That way you are using an existing tool and don't have to
write the python code.  You can probably copy another algorithm description
easily enough, but see the documentation here (the version in your QGIS
install is probably very out of date - I just updated it recently):
QGIS/python/plugins/grassprovider/grass7.txt
at master · qgis/QGIS · GitHub
<https://github.com/qgis/QGIS/blob/master/python/plugins/grassprovider/grass7.txt>

I have done some work to allow users to install GRASS addons and create
algorithm descriptions for them, so hopefully this will be available in a
QGIS release soon (my second pull request hasn't been approved and merged
yet).
See Add support for GRASS addons · Issue #53048 · qgis/QGIS (github.com)
<https://github.com/qgis/QGIS/issues/53048>

If you want to write algorithm descriptions for GRASS addons in the
meantime, you will need to install them in the QGIS installation directory,
which may require administrator rights on your computer.

Regards,
Alister

On Thu, 22 Jun 2023 at 06:44, <qgis-user-request at lists.osgeo.org> wrote:

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>    1. consultation (Juan Pablo Moreno Sebastian)
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> Message: 1
> Date: Wed, 21 Jun 2023 18:42:57 +0000
> From: Juan Pablo Moreno Sebastian <jpablotop at hotmail.com>
> To: "qgis-user at lists.osgeo.org" <qgis-user at lists.osgeo.org>
> Subject: [Qgis-user] consultation
> Message-ID:
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> Content-Type: text/plain; charset="utf-8"
>
> Good afternoon.
>
> I'm Juan Pablo Moreno.
>
> I have to develop a plugin for QGIS that calculates the orographic
> prominence of the hills and then goes on to classify the points.
> I will now explain my idea more slowly.
>
> 1? The plugin must load an MDT.
> 2? Locate hills by analysis of each cell of the MDT and those of its
> surroundings. I locate a cell and if the surroundings are of lower level it
> will be a possible hill, the holes would be the other way around.
> 3? Calculation of the orographic prominence of each hill.
> ??????
> ??????Prominence:
> ??????The prominence of a mountain is a notion used in orography for the
> classification of mountains. It is defined as the minimum slope that must
> be descended from the top of a mountain to ascend to a higher one. The more
> prominent a mountain is, the more it will stand out among those around it,
> regardless of its altitude.
> ?????
> ??????????????????Prominence = mountain altitude - altitude minimum point
>
> ??????[cid:134c04d1-db0c-4fb6-becb-4ec2ae026d73]
>
> To calculate the prominence, a program would have to be developed that did
> something similar to the following:
>
> An analogy widely used to explain these relationships and, incidentally,
> to illustrate a possible procedure for detecting hills and hills, alludes
> to the myth of the universal flood. We imagine that the earth has been
> flooded under a thick blanket of water that covers it completely, without
> leaving a single piece of land emerged. After the end of the flood, the
> evaporation of water causes small islands to begin to emerge. The first to
> appear is the summit of Everest and the following, other summits of the
> Himalayas. As the sea level drops due to evaporation, the surface area
> occupied by each island increases and there comes a time when the level is
> low enough for the island to merge with another land mass through some
> isthmus that has been exposed.  The exact point at which the connection of
> two islands occurs coincides with a col and is associated with the summit
> of the lower altitude island to determine its prominence. The value is
> obtained from the difference in height between the
>   hill and the associated hill, as can be seen from its definition.
>
> We apologize for the inconvenience.
> If you find the subject interesting or were so kind as to guide me a
> little?, tell me if it sounds like something or know something similar?,
> give me some advice on where or how to start?, or if you have another idea
> on the subject, I am very lost in python programming and everything would
> be very helpful,  I would be very grateful.
>
> Thank you very much for everything.
> Best regards.
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