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 | Maximum search distance [map units]. | Minimum: 0.000000
Default: 10000.000000 |
| Directions | Choice | DIRECTIONS | - | Available Choices:
[0] single
[1] all
Default: 1 |
| Direction | Floating point | DIRECTION | Single direction given as degree measured clockwise from the North direction. | Minimum: -360.000000
Maximum: 360.000000
Default: 315.000000 |
| Number of Sectors | Integer | NDIRS | - | Minimum: 4
Default: 8 |
| 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 |
| 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>] [-DIRECTIONS <str>] [-DIRECTION <double>] [-NDIRS <num>] [-METHOD <str>] [-DLEVEL <double>] [-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
-DIRECTIONS:<str> Directions
Choice
Available Choices:
[0] single
[1] all
Default: 1
-DIRECTION:<double> Direction
Floating point
Minimum: -360.000000
Maximum: 360.000000
Default: 315.000000
-NDIRS:<num> Number of Sectors
Integer
Minimum: 4
Default: 8
-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
-UNIT:<str> Unit
Choice
Available Choices:
[0] Radians
[1] Degree
Default: 0
-NADIR:<str> Difference from Nadir
Boolean
Default: 1