Tool Wombling (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.
- Author: O.Conrad (c) 2015
- Menu: Grid|Filter
Parameters
| Name | Type | Identifier | Description | Constraints | |
|---|---|---|---|---|---|
| Input | Feature | Grid (input) | FEATURE | - | - |
| Output | Edge Points (*) | Shapes (optional output) | EDGE_POINTS | - | - |
| Edge Segments (*) | Shapes (optional output) | EDGE_LINES | - | - | |
| Gradients (*) | Grid list (optional output) | GRADIENTS | - | - | |
| Options | Grid system | Grid system | PARAMETERS_GRID_SYSTEM | - | - |
| Minimum Magnitude | Floating point | TMAGNITUDE | Minimum magnitude as percentile. | Minimum: 0.000000 Maximum: 100.000000 Default: 90.000000 | |
| Maximum Angle | Floating point | TDIRECTION | Maximum angular difference as degree between adjacent segment points. | Minimum: 0.000000 Maximum: 180.000000 Default: 30.000000 | |
| Minimum Neighbours | Integer | 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 | |
| (*) optional | |||||
Command-line
Usage: saga_cmd grid_filter 16 [-TMAGNITUDE <double>] [-TDIRECTION <double>] [-TNEIGHBOUR <num>] [-ALIGNMENT <str>] [-NEIGHBOUR <str>] [-FEATURE <str>] [-EDGE_POINTS <str>] [-EDGE_LINES <str>] [-GRADIENTS_OUT <str>] [-GRADIENTS <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 -FEATURE:<str> Feature Grid (input) -EDGE_POINTS:<str> Edge Points Shapes (optional output) -EDGE_LINES:<str> Edge Segments Shapes (optional output) -GRADIENTS_OUT:<str> Output of Gradients Boolean Default: 0 -GRADIENTS:<str> Gradients Grid list (optional output)