[Qgis-user] doubts about the azimuth value obtained

[Thayer Young]

 Hi Enrique,
In the OGC standard the start and end points of a simple polygon will be the same point. So the azimuth will be 0. For a polygon containing rings it will probably be the start point of the outer boundary and the end point of the last ring, etc.. None of those is not going to be very helpful. Especially since the start and end points of a polygon just tell you where the person chose to start digitizing, which is not very meaningful in the real world.
How are you defining the azimuth of a dwelling?
I am assuming that the azimuth of the building polygon is the direction that the front door of a building points towards?
  If so, you might want to try finding the azimuth from the centroid of the polygon and the end point of the shortest line from the centroid to the street centerline segment that it is used for the street address, or just to the nearest street centerline. 
  FYI, Building polygons don't usually have street addresses, so you may have to get that from a spatial join with the parcel polygon, etc..

Give this some more thought and write back to the list if you still need help. Please include what else you have tried and what results you have gotten.
-Thayer

 

    On Monday, July 17, 2023 at 03:42:18 PM EDT, qgis-user-request at lists.osgeo.org <qgis-user-request at lists.osgeo.org> wrote: Date: Mon, 17 Jul 2023 19:15:18 +0200From: Enrique Sagredo Blanco <esagredo at mondragon.edu>
To: qgis-user at lists.osgeo.org
Subject: [Qgis-user] doubts about the azimuth value obtained
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    <CAKBdjWCo3nG4Ys4gR4yL_muRYrkW4wNGY--cyg90NT9jEiCY0g at mail.gmail.com>
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Good afternoon:
I am a professor at the University of Mondragon and for the research I am
carrying out I am using QGIS. I want to obtain the azimuth value of the
dwellings in a certain municipality, I have created a variable and using
code I have generated this function which I have attached.

degrees( azimuth(  start_point(  $geometry ), end_point(  $geometry )))

The doubt arises when interpreting this data, since QGIS returns a value
but I don't know how to obtain it. Since it is a unique value, I don't know
how to interpret what it means on a map. Since the polygons analysed have
four sides.

Can you help me?
Thank you very much.

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