Tool Polygon Shape Indices
Various indices describing the shape of polygons, mostly based on area, perimeter, maximum diameter.
- A area
- P perimeter
- P/A interior edge ratio
- P/sqrt(A)
- Deqpc equivalent projected circle diameter (=2*sqrt(A/pi))
- Sphericity the ratio of the perimeter of the equivalent circle to the real perimeter (=P/(2*sqrt(A*pi)))
- Shape Index the inverse of the spericity
- Dmax maximum diameter calculated as maximum distance between two polygon part's vertices
- DmaxDir direction of maximum diameter
- Dmax/A
- Dmax/sqrt(A)
- Dgyros diameter of gyration, calculated as twice the maximum vertex distance to its polygon part's centroid
- Fmax maximum Feret diameter
- FmaxDir direction of the maximum Feret diameter
- Fmin minimum Feret diameter
- FminDir direction of the minimum Feret diameter
- Fmean mean Feret diameter
- Fmax90 the Feret diameter measured at an angle of 90 degrees to that of the Fmax direction
- Fmin90 the Feret diameter measured at an angle of 90 degrees to that of the Fmin direction
- Fvol the diameter of a sphere having the same volume as the cylinder constructed by Fmin as the cylinder diameter and Fmax as its length
References
- Lang, S. & Blaschke, T. (2007): Landschaftsanalyse mit GIS. Stuttgart.
- Forman, R.T.T. & Godron, M. (1986): Landscape Ecology. Cambridge.
- Author: O.Conrad (c) 2008
- Menu: Shapes|Polygons
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Shapes | Shapes (input) | SHAPES | - | - |
| Output | Shape Indices (*) | Shapes (optional output) | INDEX | - | - |
| Maximum Diameter (*) | Shapes (optional output) | DMAX | - | - |
| Options | Diameter of Gyration | Boolean | GYROS | - | Default: 0 |
| Feret Diameters | Boolean | FERET | - | Default: 0 |
| Number of Directions | Integer | FERET_DIRS | Number of directions (0-90) to be analyzed. | Minimum: 0
Default: 18 |
| (*) optional |
Command-line
Usage: saga_cmd shapes_polygons 7 [-SHAPES <str>] [-INDEX <str>] [-DMAX <str>] [-GYROS <str>] [-FERET <str>] [-FERET_DIRS <num>]
-SHAPES:<str> Shapes
Shapes (input)
-INDEX:<str> Shape Indices
Shapes (optional output)
-DMAX:<str> Maximum Diameter
Shapes (optional output)
-GYROS:<str> Diameter of Gyration
Boolean
Default: 0
-FERET:<str> Feret Diameters
Boolean
Default: 0
-FERET_DIRS:<num> Number of Directions
Integer
Minimum: 0
Default: 18