Terrain analysis

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Terrain analysis in GRASS GIS

GRASS GIS offers an enormous range of methods and tools for terrain analysis.

(see also: Geomorphometry and Hydrological Sciences)

Accumulation

  • r.accumulate addon module: Calculates weighted flow accumulation, subwatersheds, stream networks, and longest flow paths using a flow direction map.

Analytical Hillshading

  • r.shaded.pca addon module: Creates relief shades from various directions and combines them into RGB composition

Aspect

See: r.slope.aspect: Generates raster maps of slope, aspect, curvatures and partial derivatives from an elevation raster map

Basins

  • r.basin addon module: morphometric characterization of river basins
  • r.basin.fill: Generates watershed subbasins raster map
  • r.valley.bottom addon module: Calculation of Multi-resolution Valley Bottom Flatness (MrVBF) index
  • r.watershed: Determines watersheds

Catchment Area

  • r.catchment addon module: Creates a raster buffer of specified area around vector points using cost distances using r.walk

Channel Network Base Level

See list in Hydrological Sciences

Channel Network Distance

See list in Hydrological Sciences

Closed Depressions

  • r.fill.dir: Filters and generates a depressionless elevation map and a flow direction map from a given elevation raster map

Contours

  • r.contour: Produces a vector map of specified contours from a raster map

Convergence Index

Curvatures

  • r.slope.aspect: Generates raster maps of slope, aspect, curvatures and partial derivatives from an elevation raster map

Flooding

  • r.lake: Fills lake at given point to given level

Flow and lines

  • r.flow: Computes flow-lines, flow-path lengths, and flow-accumulation (contributing areas)
  • r.accumulate addon module: Calculates weighted flow accumulation, subwatersheds, stream networks, and longest flow paths using a flow direction map.
  • r.terraflow: Performs flow computation for massive grids

Fractal surfaces

  • r.surf.fractal: Creates a fractal surface of a given fractal dimension

Habitats and terrain

  • v.habitat.dem addon module: Calculates DEM derived characteristics of habitats

Landscape evolution

Local relief model

  • r.local.relief addon module: Creates a local relief model from elevation map

LS-Factor

  • r.watershed: Calculates hydrological parameters and RUSLE factors

Multi-resolution Valley Bottom Flatness (MrVBF) index

  • r.valley.bottom addon module: Calculation of Multi-resolution Valley Bottom Flatness (MrVBF) index

Northerness, easterness

  • r.northerness.easterness addon module: Calculation of northerness, easterness and the interaction between northerness and slope

Random surfaces

  • r.random.surface: Generates random surface(s) with spatial dependence
  • r.surf.contour: Generates surface raster map from rasterized contours
  • r.surf.fractal: Creates a fractal surface of a given fractal dimension
  • r.surf.gauss: Generates a raster map using gaussian random number generator
  • r.surf.idw: Provides surface interpolation from raster point data by Inverse Distance Squared Weighting
  • r.surf.random: Produces a raster surface map of uniform random deviates with defined range

Shaded relief map

  • r.relief: Creates shaded relief map from an elevation map (DEM)

Slope

  • r.slope.aspect: Generates raster maps of slope, aspect, curvatures and partial derivatives from an elevation raster map
  • r.slope.direction addon module: Calculates slope following a direction raster

Stream channels

Surface roughness

  • r.roughness.vector addon module: Calculates surface roughness in a moving-window, as the orientation of vectors normal to surface planes.

Terrain classification

  • r.terrain.texture addon module: Unsupervised nested-means algorithm for terrain classification

Terrain forms (geomorphons)

  • r.geomorphon: Calculates geomorphons (terrain forms) and associated geometry using machine vision approach

Topographic Position Index

  • r.tpi addon module: Calculates the multiscale topographic position index

Topographic Ruggedness Index

  • r.tri addon module: Computes the Terrain Ruggedness Index

Topographic Wetness Index

See: r.topidx: Creates a topographic index (wetness index) raster map from an elevation raster map

Vector Ruggedness Measure

Watersheds

  • r.watershed: Calculates hydrological parameters and RUSLE factors
  • r.basin.fill: Generates watershed subbasins raster map

Valley Depth

  • r.valley.bottom addon module: Calculation of Multi-resolution Valley Bottom Flatness (MrVBF) index

Viewshed

  • r.viewshed: Computes the viewshed of a point on an elevation raster map
  • r.viewshed.cva addon module: Undertakes a "cumulative viewshed analysis" using a vector points map as input "viewing" locations, using r.viewshed to calculate the individual viewsheds
  • r.viewshed.exposure addon module: Visual exposure to defined exposure source

See also

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