Smathermather's Weblog

Remote Sensing, GIS, Ecology, and Oddball Techniques

What is the center line of a complex polygon? Routing Stream and Rivers

Posted by smathermather on August 9, 2012

Continuing my posts on the centerline of a complex polygon (you can work your way backward from here), here’s it’s application to a riverine system (legend: light blue river, black centerline derived from routing through the skeleton of voronoi polygons from a densified stream bank set + the skipped skeleton bits in pink– read through the series if you if you don’t grok that explaination):

8 Responses to “What is the center line of a complex polygon? Routing Stream and Rivers”

  1. Mon said

    I had to this for a job one time and found a nice ArcGIS model (ArcInfo required). Clever way of using Thiessen Polygons to do the job, am guessing the workflow is pretty similar to yours:

    I also used FME and worked pretty well too, from what I remember too ET GeoWaizards a create centerline tool.

    It would be really cool if you could do all of this in PostGIS.

    • Ahh, hadn’t seen that one. I’ll have to take a look.

      • Mon said

        Depending on how you densify, it may take a long time to finish the process especially if you have lots of features. After the trimming of the skeletons, unsplitting the lines and applying a threshold minimum length helps in cleaning further the lines and also creates line segments according to line intersections. You still have to make some manual edits but it helps a lot in minimizing the worload.

  2. Mon said

    Have you ever tried the RBT Toolkit?

    I read the documentation a bit and it sounds promising. Too bad we are not alowed to download 3rd party extensions here in the office, I was hoping to try it.

  3. Majo said


    is tihis possible in QGIS 2.x already ? – convert polygons to centerlines

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