Sunday, 15 June 2014

Self-paced Introduction to QGIS and more on DEM segmentation

I have seen recently there is a self-paced course on QGIS from the  FOSS4Geo Academy . It is hosted on the open source Canvas Learning Network.

There are two modules so far, an introductory one, and a cartography one, with more coming soon.

Following on from my last post, here is the topography of the British Isles segmented using RSGISLib using a minimum object size of 65536 pixels.

This probably isn't a useful approach, since it took the computer about 9 hours to do this. I expect it is better to use smaller objects and aggregate them at the classification stage.

Here the mean segments are colourised using yellow for slope, and blue for elevation with a gaussian stretch as before.

 And here are the segments with a random colourisation.

Using a higher resolution (5m) DEM for mid-Wales, around the Aberystwyth, Dyfi estuary and Pumlumon area, aggregating to at least 1024 pixels (that is equivalent to a 160x160m square):

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