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