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I would like to do the following:

  1. Get the area of each soilscape type

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  1. Calculate the sum of area per boundary

I'm trying to do the following but seems the output is always "0"

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Project Nice
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    What spatial reference is your data? It could be geographic which would make your area unmeaning. The geometries could be bad which could interfere with the area calc. Probably the best way of getting combined areas is, after individual polygons are calculated, open a copy of the DBF file (part of a shapefile, you might need to save as if not already a shapefile) in Excel (or similar) and create a pivot table. – Michael Stimson Jun 28 '17 at 02:25

1 Answers1

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Duplicate the layer, and perform a dissolve operation to make a polygon for every kind of soilscape How to dissolve based on attribute with QGIS

Then calculate the geometry of every polygon in a new field. Try if it works this way, maybe it is not the most elegant, but it may work for you.

Sergio C.
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    This will work, but reproject to an appropriate equal-area projection first. – obrl_soil Jun 28 '17 at 02:45
  • Then find and fix invalid geometries https://faunaliagis.wordpress.com/2013/08/14/bad-bad-polygon-fixing-invalid-geometries-with-quantum-gis/ or https://gis.stackexchange.com/questions/167421/repairing-geometry-using-qgis Incorrect ring orientation and self intersections can make the area calcs untrustworthy at best or crash QGIS at worst. – Michael Stimson Jun 28 '17 at 04:57