SAGA-GIS Module Library Documentation (v2.3.0)

Module Wombling for Multiple Features (Edge Detection)

Continuous Wombling for edge detection. Uses magnitude of gradient to detect edges between adjacent cells. Edge segments connect such edges, when the difference of their gradient directions is below given threshold.

References:
- Fitzpatrick, M.C., Preisser, E.L., Porter, A., Elkinton, J., Waller, L.A., Carlin, B.P., Ellison, A.M. (2010): Ecological boundary detection using Bayesian areal wombling. Ecology 91(12): 3448-3455. doi:10.1890/10-0807.1
- Fortin, M.-J. and Dale, M.R.T (2005): Spatial Analysis - A Guide for Ecologists. Cambridge University Press.

Parameters

 NameTypeIdentifierDescriptionConstraints
InputFeaturesGrid list (input)FEATURES--
OutputEdgesGrid list (output)EDGE_CELLS--
Output (*)Grid list (optional output)OUTPUT--
OptionsGrid systemGrid systemPARAMETERS_GRID_SYSTEMGrid system-
Minimum MagnitudeFloating pointTMAGNITUDEMinimum magnitude as percentile.Minimum: 0.000000
Maximum: 100.000000
Default: 90.000000
Maximum AngleFloating pointTDIRECTIONMaximum angular difference as degree between adjacent segment points.Minimum: 0.000000
Maximum: 180.000000
Default: 30.000000
Minimum NeighboursIntegerTNEIGHBOURMinimum number of neighbouring potential edge cells with similar direction.Minimum: 0
Default: 1
AlignmentChoiceALIGNMENT-Available Choices:
[0] between cells
[1] on cell
Default: 1
Edge ConnectivityChoiceNEIGHBOUR-Available Choices:
[0] Rooke's case
[1] Queen's case
Default: 1
Additional OutputChoiceOUTPUT_ADD-Available Choices:
[0] none
[1] gradients
[2] edge cells
Default: 0
Zero as No-DataBooleanZERO_AS_NODATA-Default: 1
(*) optional

Command-line

Usage: saga_cmd grid_filter 17 [-TMAGNITUDE <double>] [-TDIRECTION <double>] [-TNEIGHBOUR <num>] [-ALIGNMENT <str>] [-NEIGHBOUR <str>] [-FEATURES <str>] [-EDGE_CELLS <str>] [-OUTPUT_ADD <str>] [-OUTPUT <str>] [-ZERO_AS_NODATA <str>]
  -TMAGNITUDE:<double> 	Minimum Magnitude
	Floating point
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 90.000000
  -TDIRECTION:<double> 	Maximum Angle
	Floating point
	Minimum: 0.000000
	Maximum: 180.000000
	Default: 30.000000
  -TNEIGHBOUR:<num>    	Minimum Neighbours
	Integer
	Minimum: 0
	Default: 1
  -ALIGNMENT:<str>     	Alignment
	Choice
	Available Choices:
	[0] between cells
	[1] on cell
	Default: 1
  -NEIGHBOUR:<str>     	Edge Connectivity
	Choice
	Available Choices:
	[0] Rooke's case
	[1] Queen's case
	Default: 1
  -FEATURES:<str>      	Features
	Grid list (input)
  -EDGE_CELLS:<str>    	Edges
	Grid list (output)
  -OUTPUT_ADD:<str>    	Additional Output
	Choice
	Available Choices:
	[0] none
	[1] gradients
	[2] edge cells
	Default: 0
  -OUTPUT:<str>        	Output
	Grid list (optional output)
  -ZERO_AS_NODATA:<str>	Zero as No-Data
	Boolean
	Default: 1