3

I plan to use it for positioning and tracking of areas worked for underwater mining.

I am trying to draw rings using the "Rectangles Ovals Digitizing" plugin.

But there is very little info available.

1
  • do you have a centre and radius?
    – Ian Turton
    Commented Jan 3, 2018 at 17:18

4 Answers 4

4

Consider also using the "Geometry Generator" which contains functions make_circle() and difference().

Pasting this expression:

difference(make_circle($geometry, 100), make_circle($geometry, 50))

will lead to achieving the desired result, see image below.

example

2

You have the tools to create buffers in QGIS, create the first, then the second one from one center and different sizes, and then cut the smaller one...

1

Possible using the "Multi-ring buffer (constant distance)" geoalgorithm from the QGIS's Processing Toolbox (Ctrl+Alt+T).

example

Afterwards, choose the required rings, others can be easily deleted.

1

Besides the solution with "Geometry Generator" which intended to provide a visual solution, nevertheless, it is possible to achieve rings as completely new polygon layer using "Geometry by expression" geoalgorithm from the QGIS's Processing Toolbox (Ctrl+Alt+T).

Pasting this expression:

difference(make_circle($geometry, 100), make_circle($geometry, 50))

into 'Geometry expression' will lead to achieving the desired result, see the image below.

result

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