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Is there an efficient way to produce geometry from point data using QGIS?

Each point represents a feature that may require one or more geometric primitives such as circles, curves or polylines (open or closed) to represent it.

Please note that while CAD is the best tool for creating geometry I am seeking alternative methods of achieving this using QGIS without using CAD. However the final QGIS geometry needs to be exportable to CAD in a usable format.

The goal is to produce database linked maps within QGIS but be capable of supplying useful CAD geometry to clients if they request it.

Options explored so far:

  • Vector > Geoprocessing Tools > Buffer
    • This option is a good start that can approximate circles, however the geometry is segmented and when exported to CAD (using DXF) it is interpreted as hatching. Hatching requires additional processing within CAD to produce usable geometry and being restricted to segmented circles also creates problems. This approach is less efficient than programmatically creating geometry within CAD from raw point data.

  • Python scripting
    • I'm barely scratching the surface here as there is a lot to learn. If this is the best option then any advice on how to go about it is very helpful.

    Edit: This question has been rewritten to clarify the goals and outline what has been explored.

    Sangster
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      save your point data to a shapefile > https://gis.stackexchange.com/questions/283335/creating-shapefile-in-standalone-script-using-pyqgis – Mapperz Nov 28 '18 at 01:10
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      You could also try creating buffers with your points layer in order to create a polygonal geometry around them. You can generate circular or square buffers easily with the tool in QGIS Processing. – FSimardGIS Nov 28 '18 at 02:47
    • Both very helpful ideas. Still trying to work out how to do the shapefile. The buffer suggestion is promising though I only see options for straight edge polygons and while this looks ok in QGIS (given enough segments) it would be good to have actual circles to enable snap to centre within CAD. Also having trouble with exporting the layer to DXF as it assumes units to be feet and produces hatches rather than polylines. The ideas are certainly appreciated though. – Sangster Nov 28 '18 at 04:52
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      True curves aren't supported in GIS I'm afraid, only faux circles broken into very small straight line segments.

      In CAD would it be possible to replace all the points with circles?

       – TeddyTedTed Nov 28 '18 at 12:17
    • In CAD I would do it all automatically while working from home in my pyjamas. This is my preferred approach except that my employer wants me to get dressed and come to work at the office. Unfortunately they don't want to buy the same software I have spent the past 20 years working with, and instead want me to use something I call RubbishCAD. So to avoid this I need to find an alternative and I'm very interested in what may be achieved using QGIS. – Sangster Dec 07 '18 at 06:17
    • Geometry needs representation in GIS. Points are always 0-dimensional. CAD, as you use it, draws graphic primitives like Circles, they are 2-dimensional. So your task should be to find a way, draw something around points. Because GIS isn't ideal to do such things, you better look for a function inside the CAD software. Use GIS to get points, find a reasonable export format to CAD (dxf?) and turn points into graphics inside CAD. – Andreas Müller Dec 07 '18 at 07:07
    • The answer to these questions : https://gis.stackexchange.com/questions/167308/representing-uneven-tree-canopy-spread-around-point-in-qgis/248003#248003 and https://gis.stackexchange.com/questions/229961/creating-sector-lights-in-qgis/230989#230989 will give you exemples of what can be done in QGIS starting from point, exporting to CAD is another matter – J.R Sep 16 '19 at 12:17
    • And this answer should be more relevent to you https://gis.stackexchange.com/questions/244192/cant-export-geometry-generator-styling-to-dxf-alternatives – J.R Sep 16 '19 at 12:31

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    Is there an efficient way to produce geometry from point data using QGIS?

    The Shape Tools plugin does that job.
    But knowing that what can be created in QGIS are always lines or straight side polygons.

    Gabriel De Luca
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