Wombling (Edge Detection)

Author: O.Conrad (c) 2015
Menu: Grid | Filter

Description

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

	Name	Type	Identifier	Description	Constraints
Input	Feature	grid, input	`FEATURE`	-	-
Output	Edge Points	shapes, output, optional	`EDGE_POINTS`	-	-
	Edge Segments	shapes, output, optional	`EDGE_LINES`	-	-
	Gradients	grid list, output, optional	`GRADIENTS`	-	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Minimum Magnitude	floating point number	`TMAGNITUDE`	Minimum magnitude as percentile.	Minimum: 0.000000 Maximum: 100.000000 Default: 90.000000
	Maximum Angle	floating point number	`TDIRECTION`	Maximum angular difference as degree between adjacent segment points.	Minimum: 0.000000 Maximum: 180.000000 Default: 30.000000
	Minimum Neighbours	integer number	`TNEIGHBOUR`	Minimum number of neighbouring potential edge cells with similar direction.	Minimum: 0 Default: 1
	Alignment	choice	`ALIGNMENT`	-	Available Choices: [0] between cells [1] on cell Default: 1
	Edge Connectivity	choice	`NEIGHBOUR`	-	Available Choices: [0] Rooke's case [1] Queen's case Default: 1
	Output of Gradients	boolean	`GRADIENTS_OUT`	-	Default: 0

Command Line

Usage: saga_cmd grid_filter 16 [-TMAGNITUDE ] [-TDIRECTION ] [-TNEIGHBOUR ] [-ALIGNMENT ] [-NEIGHBOUR ] [-FEATURE ] [-EDGE_POINTS ] [-EDGE_LINES ] [-GRADIENTS_OUT ] [-GRADIENTS ]
  -TMAGNITUDE:	Minimum Magnitude
	floating point number
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 90.000000
  -TDIRECTION:	Maximum Angle
	floating point number
	Minimum: 0.000000
	Maximum: 180.000000
	Default: 30.000000
  -TNEIGHBOUR:   	Minimum Neighbours
	integer number
	Minimum: 0
	Default: 1
  -ALIGNMENT:    	Alignment
	choice
	Available Choices:
	[0] between cells
	[1] on cell
	Default: 1
  -NEIGHBOUR:    	Edge Connectivity
	choice
	Available Choices:
	[0] Rooke's case
	[1] Queen's case
	Default: 1
  -FEATURE:      	Feature
	grid, input
  -EDGE_POINTS:  	Edge Points
	shapes, output, optional
  -EDGE_LINES:   	Edge Segments
	shapes, output, optional
  -GRADIENTS_OUT:	Output of Gradients
	boolean
	Default: 0
  -GRADIENTS:    	Gradients
	grid list, output, optional