I tried to figure out the legend of the output for flow direction when I use the QGIS processing toolbox function from SAGA (Channel network and drainage basin). I get a raster with values from 0 to 7. The Taudem d8 uses an encoding from 1 to 8 that does not correspond with this result. Anybody knows how this is encoded?
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1Why not check online documentation?– aldo_tapiaSep 11, 2017 at 11:42
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2Thanks. I already checked this documentation and other internet resources. This documentation also states that the range is from 1-8 which is not in line with the results I get (0-7). Is it a systematic shift or a different encoding?– HansakwastSep 11, 2017 at 12:06
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1 Answer
SAGA's flow directions are coded from North = 0 :
7 0 1
6 2
5 4 3
Each GIS has its codification : for GRASS it's
3 2 1
4 8
5 6 7
and for ARcgis : http://desktop.arcgis.com/fr/arcmap/10.3/tools/spatial-analyst-toolbox/how-flow-direction-works.htm
