Morphometric Features
- Author: O.Conrad (c) 2013
- Menu: Terrain Analysis | Terrain Classification
Description
Uses a multi-scale approach by fitting quadratic parameters to any size window (via least squares) to derive slope, aspect and curvatures (optional output) for subsequent classification of morphometric features (peaks, ridges, passes, channels, pits and planes). This is the method as proposed and implemented by Jo Wood (1996) in LandSerf and GRASS GIS (r.param.scale).
Optional output is described in the following. Generalised elevation is the smoothed input DEM. Slope is the magnitude of maximum gradient. It is given for steepest slope angle and measured in degrees. Aspect is the direction of maximum gradient. Profile curvature is the curvature intersecting with the plane defined by the Z axis and maximum gradient direction. Positive values describe convex profile curvature, negative values concave profile. Plan curvature is the horizontal curvature, intersecting with the XY plane. Longitudinal curvature is the profile curvature intersecting with the plane defined by the surface normal and maximum gradient direction. Cross-sectional curvature is the tangential curvature intersecting with the plane defined by the surface normal and a tangent to the contour - perpendicular to maximum gradient direction. Minimum curvature is measured in direction perpendicular to the direction of of maximum curvature. The maximum curvature is measured in any direction.
References:
Wood, J. (1996): The Geomorphological characterisation of Digital Elevation Models. Diss., Department of Geography, University of Leicester, U.K. online.
Wood, J. (2009): Geomorphometry in LandSerf. In: Hengl, T. and Reuter, H.I. [Eds.]: Geomorphometry: Concepts, Software, Applications. Developments in Soil Science, Elsevier, Vol.33, 333-349.
LandSerf Homepage.
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Elevation | grid, input | DEM | - | - |
| Output | Morphometric Features | grid, output | FEATURES | - | - |
| Generalized Surface | grid, output, optional | ELEVATION | - | - |
| Slope | grid, output, optional | SLOPE | - | - |
| Aspect | grid, output, optional | ASPECT | - | - |
| Profile Curvature | grid, output, optional | PROFC | - | - |
| Plan Curvature | grid, output, optional | PLANC | - | - |
| Longitudinal Curvature | grid, output, optional | LONGC | - | - |
| Cross-Sectional Curvature | grid, output, optional | CROSC | - | - |
| Maximum Curvature | grid, output, optional | MAXIC | - | - |
| Minimum Curvature | grid, output, optional | MINIC | - | - |
| Options | Grid System | grid system | PARAMETERS_GRID_SYSTEM | - | - |
| Scale Radius (Cells) | integer number | SIZE | Size of processing window (= 1 + 2 * radius) given as number of cells | Minimum: 1
Default: 5 |
| Slope Tolerance | floating point number | TOL_SLOPE | Slope tolerance that defines a 'flat' surface (degrees) | Default: 1.000000 |
| Curvature Tolerance | floating point number | TOL_CURVE | Curvature tolerance that defines 'planar' surface | Default: 0.000100 |
| Distance Weighting Exponent | floating point number | EXPONENT | Exponent for distance weighting (0.0-4.0) | Minimum: 0.000000
Maximum: 4.000000
Default: 0.000000 |
| Vertical Scaling | floating point number | ZSCALE | Vertical scaling factor | Default: 1.000000 |
| Constrain | boolean | CONSTRAIN | Constrain model through central window cell | Default: 0 |
Command Line
Usage: saga_cmd ta_morphometry 23 [-DEM ] [-FEATURES ] [-ELEVATION ] [-SLOPE ] [-ASPECT ] [-PROFC ] [-PLANC ] [-LONGC ] [-CROSC ] [-MAXIC ] [-MINIC ] [-SIZE ] [-TOL_SLOPE ] [-TOL_CURVE ] [-EXPONENT ] [-ZSCALE ] [-CONSTRAIN ]
-DEM: Elevation
grid, input
-FEATURES: Morphometric Features
grid, output
-ELEVATION: Generalized Surface
grid, output, optional
-SLOPE: Slope
grid, output, optional
-ASPECT: Aspect
grid, output, optional
-PROFC: Profile Curvature
grid, output, optional
-PLANC: Plan Curvature
grid, output, optional
-LONGC: Longitudinal Curvature
grid, output, optional
-CROSC: Cross-Sectional Curvature
grid, output, optional
-MAXIC: Maximum Curvature
grid, output, optional
-MINIC: Minimum Curvature
grid, output, optional
-SIZE: Scale Radius (Cells)
integer number
Minimum: 1
Default: 5
-TOL_SLOPE: Slope Tolerance
floating point number
Default: 1.000000
-TOL_CURVE: Curvature Tolerance
floating point number
Default: 0.000100
-EXPONENT: Distance Weighting Exponent
floating point number
Minimum: 0.000000
Maximum: 4.000000
Default: 0.000000
-ZSCALE: Vertical Scaling
floating point number
Default: 1.000000
-CONSTRAIN: Constrain
boolean
Default: 0