r.northerness.easterness - GRASS GIS manual

Note: This document is for an older version of GRASS GIS that has been discontinued. You should upgrade, and read the current manual page.

NAME

r.northerness.easterness - Calculation of northerness, easterness and the interaction between northerness and slope

KEYWORDS

raster, terrain, aspect, slope, sun

SYNOPSIS

r.northerness.easterness

r.northerness.easterness --help

r.northerness.easterness elevation=name [--help] [--verbose] [--quiet] [--ui]

Flags:

--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

elevation=name [required]: Name of elevation raster map

DESCRIPTION
NOTES
EXAMPLE
REFERENCES
SEE ALSO
AUTHOR

DESCRIPTION

r.northerness.easterness calculates northerness, easterness and the interaction between northerness and slope (northerness*slope). The user must specify the input elevation raster map.

As aspect is a circular land-surface parameter, in ecology a sine or cosine transformation is often used to obtain a continuous gradient, stressing the north-south or east-west gradient (northness or eastness).

The GRASS GIS default aspect angles (cartesian) are converted to compass angles.

Calculated raster maps are:

northerness: cos(aspect)
easterness: sin(aspect)
interaction between northerness and slope: northerness*slope

The color of these raster maps are set to grey.

EXAMPLE

  # align region to DEM and habitat vector
  g.region -a raster=DEM align=DEM

  # run r.northerness.easterness
  r.northerness.easterness elevation=DEM

REFERENCES

Olaya, V. 2009. Basic Land-Surface Parameters. In: Hengl, T. & Reuter, H.I. (eds.) 2009. Geomorphometry. Concepts, Software, Applications. Developments in Soil Science, Volume 33. Elsevier.

AUTHOR

Helmut Kudrnovsky

SOURCE CODE

Available at: r.northerness.easterness source code (history)

Latest change: Wednesday Mar 11 08:17:30 2026 in commit: 2a14bbb9928039c7c7d0ac539d42b08ff72c88f7