Spatial Attributes:

Morphological Indicators :

STSpatialAttributeCommand(functionsToApply, layer, outputLayerName).execute()
  • functionsToApply (list) – A list of one or more of the following parameters to be calculated : Area, Perimeter, NbConcavities, PerimeterConvexityDefect, AreaConvexityDefect, GraveliusIndex, MillerIndex
  • layer (QgsVectorLayer) – A vector layer containg polygonal geometries
  • outputLayerName (string) – If None, “layer_%s” %(functionsToApply)

A copy of the input QgsVectorLayer with attributes corresponding to the selected functions.

Though the shape are area indicators are self-explanatory, the other attributes may need an explanation :

  • NbConcavities is the number of spaces left after calculating the largest convex space of the polygon
  • The Perimeter Convexity Defect is the ratio between the length of the shape’s contour and that of its convex hull.
  • The Area Convexity Defect is the ratio between the area shape and its convex hull.
  • The Gravelius Index is an indicator of circularity
  • The Miller Index is the overal direction of the shape

The outuput layer of the Spatial Attribute Command function and its attributes window