Author: GRASS Development Team

## GRASS GIS 6.2.3 Reference Manual

Geographic Resources Analysis Support System, commonly referred to as GRASS, is a Geographic Information System (GIS) used for geospatial data management and analysis, image processing, graphics/maps production, spatial modeling, and visualization. GRASS is currently used in academic and commercial settings around the world, as well as by many governmental agencies and environmental consulting companies.

This reference manual details the use of modules distributed with Geographic Resources Analysis Support System (GRASS), an open source (GNU GPL'ed), image processing and geographic information system (GIS).

### Quick Introduction

- GRASS startup manual page
- How to start with GRASS
- Introductions
  - 2D raster map processing
  - 3D raster map (voxel) processing
  - Image processing
  - Database management
  - Vector map processing and network analysis
  - Projections and spatial transformations
  - SQL support
  - Display drivers
  - GRASS variables and environment variables
- The GRASS Extensions Manager (GEM)

raster commands:

r.average | Finds the average of values in a cover map within areas assigned the same category value in a user-specified base map.
r.basins.fill | Generates a raster map layer showing watershed subbasins.
r.bilinear | Bilinear interpolation utility for raster map layers.
r.bitpattern | Compares bit patterns with a raster map
r.blend | Blends color components of two raster maps by a given ratio
r.buffer | Creates a raster map layer showing buffer zones surrounding cells that contain non-NULL category values.
r.carve | Takes vector stream data, transforms it to raster, and subtracts depth from the output DEM
r.cats | Prints category values and labels associated with user-specified raster map layers.
r.circle | Creates a raster map containing concentric rings around a given point
r.clump | Recategorizes data in a raster map layer by grouping cells that form physically discrete areas into unique categories.
r.coin | Tabulates the mutual occurrence (coincidence) of categories for two raster map layers.
r.colors | Creates/Modifies the color table associated with a raster map layer.
r.composite | Combines red, green and blue map layers into a single composite map layer.
r.compress | Compresses and decompresses raster files.
r.contour | Produces a GRASS binary vector map of specified contours from GRASS raster map layer.
r.cost | Outputs a raster map layer showing the cumulative cost of moving between different geographic locations on an input raster map layer whose cell category values represent cost.
r.covar | Outputs a covariance/correlation matrix for user-specified raster map layer(s).
r.cross | Creates a cross product of the category values from multiple raster map layers.
r.describe | Prints terse list of category values found in a raster map layer.
r.digit | Interactive tool used to draw and save vector features on a graphics monitor using a pointing device (mouse) and save to a raster map.
r.distance | Locates the closest points between objects in two raster maps.
r.drain | Traces a flow through an elevation model on a raster map layer.
r.fill.dir | Filters and generates a depressionless elevation map and a flow direction map from a given elevation layer
r.fillnulls | Fills no-data areas in raster maps using v.surf.rst splines interpolation
r.flow | Construction of slope curves (flowlines), flowpath lengths, and flowline densities (upslope areas) from a raster digital elevation model (DEM)
r.grow | Generates a raster map layer with contiguous areas grown by one cell.
r.his | Generates red, green and blue raster map layers combining hue, intensity, and saturation (his) values from user-specified input raster map layers.
r.in.arc | Convert an ESRI ARC/INFO ascii raster file (GRID) into a (binary) raster map layer.
r.in.ascii | Convert an ASCII raster text file into a (binary) raster map layer.
r.in.aster | r.in.aster - georeferencing, rectification, and import of Terra-ASTER imagery and relative DEM's using gdalwarp
r.in.bin | Import a binary raster file into a GRASS raster map layer.
r.in.gdal | Import GDAL supported raster file into a binary raster map layer.
r.in.gridatb | Imports GRIDATB.FOR map file (TOPMODEL) into GRASS raster map
r.in.mat | Import a binary MAT-File(v4) to a GRASS raster.
r.in.poly | Create raster maps from ascii polygon/line data files in the current directory.
r.in.srtm | Import SRTM HGT files into GRASS
r.in.wms | Downloads and imports data from WMS servers
r.in.xyz | Create a raster map from an assemblage of many coordinates using univariate statistics.
r.info | Outputs basic information about a user-specified raster map layer.
r.kappa | Calculate error matrix and kappa parameter for accuracy assessment of classification result.
r.lake | Fills lake from seed at given level
r.le.patch | Calculates attribute, patch size, core (interior) size, shape, fractal dimension, and perimeter measures for sets of patches in a landscape.
r.le.pixel | Contains a set of measures for attributes, diversity, texture, juxtaposition, and edge.
r.le.setup | Interactive tool used to setup the sampling and analysis framework that will be used by the other r.le programs.
r.le.trace | Display the boundary of each r.le patch and show how the boundary is traced, display the attribute, size, perimeter, and shape indices for each patch, and save the data in an output file.
r.los | Line-of-sight raster analysis program.
r.mapcalc |
r.mapcalculator | r.mapcalculator - Calculates new raster map from r.mapcalc expression
r.mask | Create a MASK for limiting raster operation
r.median | Finds the median of values in a cover map within areas assigned the same category value in a user-specified base map.
r.mfilter | Raster file matrix filter.
r.mode | Finds the mode of values in a cover map within areas assigned the same category value in a user-specified base map.
r.neighbors | Makes each cell category value a function of the category values assigned to the cells around it, and stores new cell values in an output raster map layer.
r.null | Creates explicitly the NULL-value bitmap file.
r.out.arc | Converts a raster map layer into an ESRI ARCGRID file.
r.out.ascii | Converts a raster map layer into an ASCII text file.
r.out.bin | Exports a GRASS raster to a binary array.
r.out.gdal | Exports GRASS raster data into various formats (requires GDAL)
r.out.gridatb | Exports GRASS raster map to GRIDATB.FOR map file (TOPMODEL)
r.out.mat | Exports a GRASS raster to a binary MAT-File.
r.out.mpeg | Raster File Series to MPEG Conversion Program.
r.out.png | Export GRASS raster as non-georeferenced PNG image format.
r.out.pov | Converts a raster map layer into a height-field file for POVRAY.
r.out.ppm | Converts a GRASS raster file to a PPM image file at the pixel resolution of the CURRENTLY DEFINED REGION.
r.out.ppm3 | Converts 3 GRASS raster layers (R,G,B) to a PPM image file at the pixel resolution of the CURRENTLY DEFINED REGION.
r.out.tiff | Exports a GRASS raster file to a 8/24bit TIFF image file at the pixel resolution of the currently defined region.
r.out.vrml | Export a raster map to the Virtual Reality Modeling Language (VRML)
r.out.vtk | Converts raster maps into the VTK-Ascii format
r.param.scale | Extracts terrain parameters from a DEM. Uses a multi-scalar approach by taking fitting quadratic parameters to any size window (via least squares)
r.patch | Creates a composite raster map layer by using known category values from one (or more) map layer(s) to fill in areas of "no data" in another map layer.
r.plane | Creates raster plane map given dip (inclination), aspect (azimuth), and one point
r.profile | Outputs the raster map layer values lying on user-defined line(s).
r.proj | Re-project a raster map from one location to the current location.
r.quant | This routine produces the quantization file for a floating-point map.
r.random.cells | Generates random cell values with spatial dependence.
r.random | Creates a raster map layer and vector point map containing randomly located sites.
r.random.surface | Generates random surface(s) with spatial dependence.
r.reclass.area | Reclasses a raster map greater or less than user specified area size (in hectares)
r.reclass | Creates a new map layer whose category values are based upon the user's reclassification of categories in an existing raster map layer.
r.recode | Recode raster maps.
r.region | Sets the boundary definitions for a raster map.
r.regression.line | Calculates linear regression from two raster maps: y = a + b*x
r.report | Reports statistics for raster map layers.
r.resamp.rst | Reinterpolates and computes topographic analysis from input raster file to a new raster file (possibly with different resolution) using regularized spline with tension and smoothing.
r.resample | GRASS raster map layer data resampling capability.
r.rescale.eq | Rescales histogram equalized the range of category values in a raster map layer.
r.rescale | Rescales the range of category values in a raster map layer.
r.ros | Generates three, or four raster map layers showing 1) the base (perpendicular) rate of spread (ROS), 2) the maximum (forward) ROS, 3) the direction of the maximum ROS, and optionally 4) the maximum potential spotting distance.
r.series | Makes each output cell value a function of the values assigned to the corresponding cells in the input raster map layers.
r.shaded.relief | Creates shaded relief map from an elevation map (DEM).
r.sim.sediment | Overland flow hydrologic model based on duality particle-field concept (SIMWE)
r.sim.water | Overland flow hydrologic model based on duality particle-field concept (SIMWE)
r.slope.aspect | Generates raster map layers of slope, aspect, curvatures and partial derivatives from a raster map layer of true elevation values. Aspect is calculated counterclockwise from east.
r.spread | Simulates elliptically anisotropic spread on a graphics window and generates a raster map of the cumulative time of spread, given raster maps containing the rates of spread (ROS), the ROS directions and the spread origins. It optionally produces raster maps to contain backlink UTM coordinates for tracing spread paths.
r.spreadpath | Recursively traces the least cost path backwards to cells from which the cumulative cost was determined.
r.statistics | Category or object oriented statistics.
r.stats | Generates area statistics for raster map layers.
r.sum | Sums up the raster cell values.
r.sun | Computes direct (beam), diffuse and reflected solar irradiation raster maps for given day, latitude, surface and atmospheric conditions. Solar parameters (e.g. sunrise, sunset times, declination, extraterrestrial irradiance, daylight length) are saved in the map history file. Alternatively, a local time can be specified to compute solar incidence angle and/or irradiance raster maps. The shadowing effect of the topography is optionally incorporated.
r.sunmask | Calculates cast shadow areas from sun position and DEM. Either A: exact sun position is specified, or B: date/time to calculate the sun position by r.sunmask itself.
r.support | Allows creation and/or modification of raster map layer support files.
r.surf.area | Surface area estimation for rasters.
r.surf.contour | Surface generation program from rasterized contours.
r.surf.fractal | Creates a fractal surface of a given fractal dimension.
r.surf.gauss | GRASS module to produce a raster map layer of gaussian deviates whose mean and standard deviation can be expressed by the user. It uses a gaussian random number generator.
r.surf.idw | Surface interpolation utility for raster map layers.
r.surf.idw2 | Surface generation program.
r.surf.random | Produces a raster map layer of uniform random deviates whose range can be expressed by the user.
r.terraflow | Flow computation for massive grids (Float version).
r.texture | Generate images with textural features from a raster map
r.thin | Thins non-zero cells that denote linear features in a raster map layer.
r.tileset | Produces tilings of the source projection for use in the destination region and projection.
r.timestamp | Print/add/remove a timestamp for a raster map.
r.to.rast3 | Converts 2D raster map slices to one 3D raster volume map
r.to.rast3elev | Creates a 3D volume map based on 2D elevation and value raster maps
r.to.vect | Converts a raster map into a vector map layer.
r.topidx | Creates topographic index, ln(a/tan(beta)), map from elevation map.
r.topmodel | Simulates TOPMODEL which is a physically based hydrologic model.
r.transect | Outputs raster map layer values lying along user defined transect line(s).
r.univar | Calculates univariate statistics from the non-null cells of a raster map.
r.univar.sh | calculates univariate statistics from a GRASS raster map
r.volume | Calculates the volume of data "clumps", and (optionally) produces a GRASS vector points map containing the calculated centroids of these clumps.
r.walk | Outputs a raster map layer showing the anisotropic cumulative cost of moving between different geographic locations on an input elevation raster map layer whose cell category values represent elevation combined with an input raster map layer whose cell values represent friction cost.
r.water.outlet | Watershed basin creation program.
r.watershed | Watershed basin analysis program.
r.what | Queries raster map layers on their category values and category labels.

Help Index | Full Index
© 2003-2007 GRASS Development Team