SAGA-GIS Module Library Documentation (v2.3.0)

Module 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. online 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. online at ASPRS.

Parameters

 NameTypeIdentifierDescriptionConstraints
InputElevationGrid (input)DEM--
OutputPositive OpennessGrid (output)POS--
Negative OpennessGrid (output)NEG--
OptionsGrid systemGrid systemPARAMETERS_GRID_SYSTEMGrid system-
Radial LimitFloating pointRADIUS-Minimum: 0.000000
Default: 10000.000000
MethodChoiceMETHOD-Available Choices:
[0] multi scale
[1] sectors
Default: 1
Multi Scale FactorFloating pointDLEVEL-Minimum: 1.250000
Default: 3.000000
Number of SectorsIntegerNDIRS-Minimum: 2
Default: 8

Command-line

Usage: saga_cmd ta_lighting 5 [-DEM <str>] [-POS <str>] [-NEG <str>] [-RADIUS <double>] [-METHOD <str>] [-DLEVEL <double>] [-NDIRS <num>]
  -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] sectors
	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