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I have the task of inserting a polygon in a map with a specific size. My idea is to simply "draw" a polygon and keep on enhacing its size, until it reaches the size I actually want to be. Its basically an easy task, but i'm wondering if i could directly have the polygon in the size i want it to be. I went through the vector-tools, but nothing seemed to do the trick. I'm using QGIS 2.18.3 (Las Palmas)

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  • what sort of polygon? size as length or area?
    – Ian Turton ♦
    Sep 21, 2017 at 12:05
  • area!The polygon doesnt even have to have a specific shape...
    – rtaani
    Sep 21, 2017 at 12:06

2 Answers 2

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You can use QAD Plugin to draw a regular polygon with a specific area. For example, if you want to draw a polygon with an area of 50000 square meter you can do the following:

  1. Select regular polygon as you can see below: enter image description here
  2. Specify the number of edges at the command line below (I chose 6), and click enter enter image description here
  3. Specify Center of the polygon or Edge: clicked on target position on the screen
  4. Enter an option [Inscibed in Circle/Circumscribed about circle/Area]: Choose Area enter image description here
  5. Enter the polygon area: Choose the specific area you want, 50000 for example

enter image description here

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  • This works! I'm still struggeling with the area, there is a gap between what i insert and what i calculate (for verification), but i'm sure its a small issue which is manageable! Thanks
    – rtaani
    Sep 22, 2017 at 12:20
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    The QAD plugin is not compatible with v3.xxx
    – Eddie Arni
    Jan 11, 2019 at 19:19
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If it does not need to be QGIS have a try with OpenJUMP. With the Draw circle tool you can define the size and then create circles of fixed size with just one click.

enter image description here

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  • Hi, Thanks for the quick reply. We dont have OpenJUMP at work. I will look into it anyway
    – rtaani
    Sep 21, 2017 at 12:39
  • The normal Draw polygon tool shows the area in real time when you draw a new feature but unfortunately the other circle tool that is used by dragging the circle to the desired size shows only perimeter in real time.
    – user30184
    Sep 21, 2017 at 12:50
  • Hi, I can't chose the number of side I want for my polygon, neither the size with QAD... can you explain how did you do?
    – Robagb
    Apr 11 at 7:04
  • Did you notice this is OpenJUMP? My answer was using the Draw circle with given radius and center from the standard toolbox. It does not have a direct input for the number of sides. Accuracy has an indirect effect but does not allow to draw triangles, for example. There is indeed a special tool in the CAD toolbox "Draw regular concyclic polygon" that takes radius and number of sides as input. The result is a closed linestring but it can be converted into polygon easily. I tried and had no problem with using that CAD tool. Just select the tool, fill in the parameters, and click on the map.
    – user30184
    Apr 11 at 7:26

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