Tool Topographic Openness
Topographic openness expresses the dominance (positive) or enclosure (negative) of a landscape location. See Yokoyama et al. (2002) for a precise definition. Openness has been related to how wide a landscape can be viewed from any position. It has been proven to be a meaningful input for computer aided geomorphological mapping.
References
- Anders, N. S. / Seijmonsbergen, A. C. / Bouten, W. (2009): Multi-Scale and Object-Oriented Image Analysis of High-Res LiDAR Data for Geomorphological Mapping in Alpine Mountains. Proceedings of Geomorphometry 2009. pdf at geomorphometry.org.
- Prima, O.D.A / Echigo, A. / Yokoyama, R. / Yoshida, T. (2006): Supervised landform classification of Northeast Honshu from DEM-derived thematic maps. Geomorphology, vol.78, pp.373-386.
- Yokoyama, R. / Shirasawa, M. / Pike, R.J. (2002): Visualizing topography by openness: A new application of image processing to digital elevation models. Photogrammetric Engineering and Remote Sensing, Vol.68, pp.251-266 pdf at ASPRS.
- Author: O.Conrad (c) 2012
- Menu: Terrain Analysis|Lighting
Parameters
| Name | Type | Identifier | Description | Constraints | |
|---|---|---|---|---|---|
| Input | Elevation | Grid (input) | DEM | - | - |
| Output | Positive Openness | Grid (output) | POS | - | - |
| Negative Openness | Grid (output) | NEG | - | - | |
| Options | Grid System | Grid system | PARAMETERS_GRID_SYSTEM | - | - |
| Radial Limit | Floating point | RADIUS | - | Minimum: 0.000000 Default: 10000.000000 | |
| Method | Choice | METHOD | - | Available Choices: [0] multi scale [1] line tracing Default: 1 | |
| Multi Scale Factor | Floating point | DLEVEL | - | Minimum: 1.250000 Default: 3.000000 | |
| Number of Sectors | Integer | NDIRS | - | Minimum: 2 Default: 8 | |
| Unit | Choice | UNIT | - | Available Choices: [0] Radians [1] Degree Default: 0 | |
| Difference from Nadir | Boolean | NADIR | If set, output angles are the mean difference from nadir, or else from a plane. | Default: 1 |
Command-line
Usage: saga_cmd ta_lighting 5 [-DEM <str>] [-POS <str>] [-NEG <str>] [-RADIUS <double>] [-METHOD <str>] [-DLEVEL <double>] [-NDIRS <num>] [-UNIT <str>] [-NADIR <str>] -DEM:<str> Elevation Grid (input) -POS:<str> Positive Openness Grid (output) -NEG:<str> Negative Openness Grid (output) -RADIUS:<double> Radial Limit Floating point Minimum: 0.000000 Default: 10000.000000 -METHOD:<str> Method Choice Available Choices: [0] multi scale [1] line tracing Default: 1 -DLEVEL:<double> Multi Scale Factor Floating point Minimum: 1.250000 Default: 3.000000 -NDIRS:<num> Number of Sectors Integer Minimum: 2 Default: 8 -UNIT:<str> Unit Choice Available Choices: [0] Radians [1] Degree Default: 0 -NADIR:<str> Difference from Nadir Boolean Default: 1