We are working with peatland restoration sites providing aerial photogrammetry of the restoration progress. We want to differentiate between areas water and bare peat which can look very similar in the orthomosaic raster. However, in the DEM the water features are instantly recognisable as they have a jagged and irregular surface. We can hillshade the DEM to show these areas and manually map them, but is there an easy way to automate this in QGIS?

Started playing with OTB and object based classification but not sure how to achieve this from the DEM as it's a single band raster.

Update, photos show a section of the orthomosaic, then the classified raster with bare peat (black), water (blue), vegetation (heather - green), and unclassified (transparent, showing the ortho below). It would be a great help to make the water areas solid and export as a shapefile.

Unprocessed orthomosaic raster Processed image showing bare peat, water and heather

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    QGIS offers a terrain ruggedness algorithms which you may find useful if you play with the parameters. You can find these tools in the processing toolbox under GDAL/OGR Analysis as TRI or in the SAGA toolbox under Terrain Analysis. – GBG Feb 27 '19 at 16:53
  • You'll probably get much better advice if you show some images of your data. – Jon Feb 27 '19 at 17:09
  • @GBG the terrain analysis tool shows up the water areas clearly, thank you. The next task is to isolate the water areas from the other “noise” across the raster and export them as shape files. – RoryG Feb 27 '19 at 18:19
  • Does your data by any chance contain a near infrared band? That would be the most reliable way to classify water. – Rob Mar 1 '19 at 9:11

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