shape.index {doolkit}

shape.index

Description

Compute various shape indices.

Usage

shape.index(mesh, origin = TRUE)

Arguments

mesh

object of class mesh3d

origin

logical, if TRUE the z of the mesh is adjusted so that the lowest z = 0; see dkorigin

Details

A handful of indices have been developed to characterize the shape of natural landscapes, including drainage basins. While some indices are very scale-sensitive (e.g., Gravelius' compactness coefficient), others are dimensionless. Horton (1932) introduced a form factor computed as the quotient of the basin's surface area over the square of the maximum basin length. Schumm (1956) developed a basin elongation index computed as the quotient of twice the square root of surface area over the product of basin length and the squareroot of pi. Lastly, Chorley et al. (1957) developed a lemniscate ratio which corresponds to the ratio between the surface of a lemniscate of same length over the basin area,and computed as (pi*(Length^2))/(4*Area).

Value

A list of indices:

• Form factor (Horton, 1932)

• Basin elongation (Schum, 1956)

• Lemniscate ratio 'K' (Chorley et al., 1957)

References

doi:10.1029/TR013i001p00350Horton (1932)

doi:10.1130/0016-7606(1956)67[597:EODSAS]2.0.CO;2Schumm (1956)

doi:10.2475/ajs.255.2.138Chorley et al. (1957)

Examples

ShapInd <- shape.index(dkmodel$basin)
ShapInd$FormFactor
ShapInd$Elongation
ShapInd$K