The following processes are supported by the GRASS Backend:

- 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.
- v.net.flow, Computes the maximum flow between two sets of nodes in the network.
- r.univar, Calculates univariate statistics from the non-null cells of a raster map.
- v.to.rast, Converts (rasterize) a vector map into a raster map.
- v.select, Selects features from vector map (A) by features from other vector map (B).
- r.li.simpson, Calculates Simpson's diversity index on a raster map
- r.li.shannon, Calculates Shannon's diversity index on a raster map
- v.split, Splits vector lines to shorter segments.
- r.param.scale, Uses a multi-scale approach by taking fitting quadratic parameters to any size window (via least squares).
- r.support, Allows creation and/or modification of raster map layer support files.
- r.li.padcv, Calculates coefficient of variation of patch area on a raster map
- i.gensigset, Generates statistics for i.smap from raster map.
- v.parallel, Creates parallel line to input vector lines.
- i.emissivity, Computes emissivity from NDVI, generic method for spares land.
- 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.
- v.kernel, Generates a raster density map from vector points data using a moving 2D isotropic Gaussian kernel or optionally generates a vector density map on vector network with a 1D kernel.
- r.circle, Creates a raster map containing concentric rings around a given point.
- v.build.polylines, Builds polylines from lines or boundaries.
- r.flow, Construction of slope curves (flowlines), flowpath lengths, and flowline densities (upslope areas) from a elevation raster map.
- r.terraflow, Flow computation for massive grids (float version).
- v.net.allpairs, Computes the shortest path between all pairs of nodes in the network.
- v.lidar.correction, Correction of the v.lidar.growing output. It is the last of the three algorithms for LIDAR filtering.
- r3.mask, Establishes the current working 3D raster mask.
- v.category, Attaches, deletes or reports vector categories to map geometry.
- r.sunmask, Either exact sun position (A) is specified, or date/time to calculate the sun position (B) by r.sunmask itself.
- v.net.salesman, Note that TSP is NP-hard, heuristic algorithm is used by this module and created cycle may be sub optimal
- r.support.stats, Update raster map statistics
- r.li.mpa, Calculates mean pixel attribute index on a raster map
- v.build, Creates topology for vector map.
- v.net.bridge, Computes bridges and articulation points in the network.
- r.reclass, Creates a new raster map whose category values are based upon a reclassification of the categories in an existing raster map.
- v.extract, Selects vector objects from an existing vector map and creates a new map containing only the selected objects.
- r.lake, Fills lake from seed at given level.
- r.slope.aspect, Aspect is calculated counterclockwise from east.
- r.li.mps, Calculates mean patch size index on a raster map, using a 4 neighbour algorithm
- i.landsat.toar, Calculates top-of-atmosphere radiance or reflectance and temperature for Landsat MSS/TM/ETM+.
- v.to.points, Creates points along input lines in new vector map with 2 layers.
- r.li.shape, Calculates shape index on a raster map
- i.rectify, Rectifies an image by computing a coordinate transformation for each pixel in the image based on the control points.
- r.topmodel, Simulates TOPMODEL which is a physically based hydrologic model.
- v.net.centrality, Computes degree, centrality, betweeness, closeness and eigenvector centrality measures in the network.
- v.net.components, Computes strongly and weakly connected components in the network.
- r.cost, Creates a raster map showing the cumulative cost of moving between different geographic locations on an input raster map whose cell category values represent cost.
- r.water.outlet, Creates watershed basins.
- i.smap, Performs contextual image classification using sequential maximum a posteriori (SMAP) estimation.
- m.cogo, It assumes a cartesian coordinate system
- r.region, Sets the boundary definitions for a raster map.
- v.distance, Finds the nearest element in vector map 'to' for elements in vector map 'from'.
- i.zc, Zero-crossing "edge detection" raster function for image processing.
- r3.timestamp, Print/add/remove a timestamp for a 3D raster map
- r.li.patchnum, Calculates patch number index on a raster map, using a 4 neighbour algorithm.
- v.net.visibility, Visibility graph construction.
- v.outlier, Removes outliers from vector point data.
- v.surf.rst, Spatial approximation and topographic analysis from given point or isoline data in vector format to floating point raster format using regularized spline with tension.
- r.cross, Creates a cross product of the category values from multiple raster map layers.
- r.li.cwed, Calculates contrast weighted edge density index on a raster map
- v.to.3d, Performs transformation of 2D vector features to 3D.
- v.normal, Tests for normality for vector points.
- r.li.dominance, Calculates dominance's diversity index on a raster map
- i.atcorr, 6S - Second Simulation of Satellite Signal in the Solar Spectrum.
- r.resamp.interp, Resamples raster map layers to a finer grid using interpolation.
- r3.mapcalc, Raster map calculator.
- v.surf.bspline, Bicubic or bilinear spline interpolation with Tykhonov regularization.
- r.carve, Takes vector stream data, transforms it to raster and subtracts depth from the output DEM.
- v.overlay, Overlays two vector maps.
- r.texture, Generate images with textural features from a raster map.
- i.evapo.time_integration, Computes temporal integration of satellite ET actual (ETa) following the daily ET reference (ETo) from meteorological station(s)
- r.solute.transport, Numerical calculation program for transient, confined and unconfined solute transport in two dimensions
- v.kcv, Randomly partition points into test/train sets.
- i.pca, Principal components analysis (pca) program for image processing.
- v.net.distance, Finds the shortest paths from a feature 'to' to every feature 'from' and various information about this realtion are uploaded to the attribute table.
- v.net.alloc, Centre node must be opened (costs >= 0). Costs of centre node are used in calculation
- v.univar, Variance and standard deviation is calculated only for points if specified.
- 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.
- i.rgb.his, Transforms raster maps from RGB (Red-Green-Blue) color space to HIS (Hue-Intensity-Saturation) color space.
- 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.
- i.gensig, Generates statistics for i.maxlik from raster map.
- r.li.patchdensity, Calculates patch density index on a raster map, using a 4 neighbour algorithm
- r.to.vect, Converts a raster map into a vector map.
- v.lidar.growing, Building contour determination and Region Growing algorithm for determining the building inside
- r.spreadpath, Recursively traces the least cost path backwards to cells from which the cumulative cost was determined.
- r.statistics2, Calculates category or object oriented statistics (accumulator-based statistics).
- v.net.connectivity, Computes vertex connectivity between two sets of nodes in the network.
- v.net.path, Finds shortest path on vector network.
- r.statistics3, Compute category quantiles using two passes.
- r.compress, Compresses and decompresses raster maps.
- r3.stats, Generates volume statistics for raster3d maps.
- r.los, Line-of-sight raster analysis program.
- v.type, Changes type of vector features.
- v.net.steiner, Note that 'Minimum Steiner Tree' problem is NP-hard and heuristic algorithm is used in this module so the result may be sub optimal
- v.delaunay, Creates a Delaunay triangulation from an input vector map containing points or centroids.
- i.maxlik, Classification is based on the spectral signature information generated by either i.cluster, i.class, or i.gensig.
- i.eb.eta, actual evapotranspiration for diurnal period (Bastiaanssen, 1995)
- v.class, Classifies attribute data, e.g. for thematic mapping
- v.extrude, Extrudes flat vector features to 3D with defined height.
- i.vi, Uses red and nir bands mostly, and some indices require additional bands.
- v.convert, Imports older versions of GRASS vector maps.
- r.distance, Locates the closest points between objects in two raster maps.
- 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.
- v.hull, Produces a convex hull for a given vector map.
- i.ifft, Inverse Fast Fourier Transform (IFFT) for image processing.
- i.cca, Canonical components analysis (cca) program for image processing.
- r.fill.dir, Filters and generates a depressionless elevation map and a flow direction map from a given elevation raster map.
- v.lrs.where, Finds line id and real km+offset for given points in vector map using linear reference system.
- m.measure, Measures the lengths and areas of features.
- v.perturb, Random location perturbations of vector points.
- r.bitpattern, Compares bit patterns with a raster map.
- v.neighbors, Makes each cell value a function of the attribute values assigned to the vector points or centroids around it, and stores new cell values in an output raster map.
- v.net, Performs network maintenance.
- i.eb.soilheatflux, Soil heat flux approximation (Bastiaanssen, 1995)
- r.kappa, Calculate error matrix and kappa parameter for accuracy assessment of classification result.
- r.surf.idw, Surface interpolation utility for raster map.
- r.null, Manages NULL-values of given raster map.
- r.mapcalc, Raster map calculator.
- r.uslek, Computes USLE Soil Erodibility Factor (K).
- r.usler, Computes USLE R factor, Rainfall erosivity index.
- v.vol.rst, Interpolates point data to a G3D grid volume using regularized spline with tension (RST) algorithm.
- v.support, Updates vector map metadata.
- r.topidx, Creates topographic index map from elevation raster map.
- i.eb.evapfr, Computes evaporative fraction (Bastiaanssen, 1995) and root zone soil moisture (Makin, Molden and Bastiaanssen, 2001)
- r.report, Reports statistics for raster map layers.
- r.surf.idw2, Surface generation program.
- r.regression.line, Calculates linear regression from two raster maps: y = a + b*x.
- r.basins.fill, Generates watershed subbasins raster map.
- r.timestamp, Print/add/remove a timestamp for a raster map.
- v.net.spanningtree, Computes minimum spanning tree for the network.
- v.patch, Creates a new vector map by combining other vector maps.
- r3.to.rast, Converts 3D raster maps to 2D raster maps
- r.grow.distance, Generates a raster map of distance to features in input raster map.
- v.db.connect, Prints/sets DB connection for a vector map to attribute table.
- r.resamp.filter, Resamples raster map layers using an analytic kernel.
- v.surf.idw, Surface interpolation from vector point data by Inverse Distance Squared Weighting.
- v.to.db, Populates database values from vector features.
- r.recode, Recodes categorical raster maps.
- r3.univar, Calculates univariate statistics from the non-null 3d cells of a raster3d map.
- r.covar, Outputs a covariance/correlation matrix for user-specified raster map layer(s).
- v.edit, Edits a vector map, allows adding, deleting and modifying selected vector features.
- v.net.timetable, Finds shortest path using timetables.
- i.sunhours, creates a sunshine hours map
- r.coin, Tabulates the mutual occurrence (coincidence) of categories for two raster map layers.
- v.generalize, Tool for vector based generalization.
- r.category, Manages category values and labels associated with user-specified raster map layers.
- v.transform, Performs an affine transformation (shift, scale and rotate, or GPCs) on vector map.
- i.landsat.acca, Landsat TM/ETM+ Automatic Cloud Cover Assessment (ACCA).
- i.biomass, Computes biomass growth, precursor of crop yield calculation
- r.surf.contour, Generates surface raster map from rasterized contours.
- v.lrs.create, Create Linear Reference System
- r.rescale, Rescales the range of category values in a raster map layer.
- v.drape, Converts vector map to 3D by sampling of elevation raster map.
- r.transect, Outputs raster map layer values lying along user defined transect line(s).
- v.qcount, Indices for quadrat counts of sites lists.
- v.clean, Toolset for cleaning topology of vector map.
- r.stats, Generates area statistics for raster map layers.
- r.surf.area, Surface area estimation for rasters.
- r.quant, Produces the quantization file for a floating-point map.
- r.li.padrange, Calculates range of patch area size on a raster map
- i.target, Targets an imagery group to a GRASS location and mapset.
- v.lrs.segment, Creates points/segments from input lines, linear reference system and positions read from stdin or a file.
- r.random, Creates a raster map layer and vector point map containing randomly located points.
- r.li.padsd, Calculates standard deviation of patch area a raster map
- r3.null, Explicitly create the 3D NULL-value bitmap file.
- r.clump, Recategorizes data in a raster map by grouping cells that form physically discrete areas into unique categories.
- r.to.rast3, Converts 2D raster map slices to one 3D raster volume map.
- r.profile, Outputs the raster map layer values lying on user-defined line(s).
- r.his, Generates red, green and blue raster map layers combining hue, intensity and saturation (HIS) values from user-specified input raster map layers.
- i.modis.qc, Extract quality control parameters from Modis QC layers
- r.resamp.rst, Reinterpolates and optionally computes topographic analysis from input raster map to a new raster map (possibly with different resolution) using regularized spline with tension and smoothing.
- r.spread, It optionally produces raster maps to contain backlink UTM coordinates for tracing spread paths.
- r.series, Makes each output cell value a function of the values assigned to the corresponding cells in the input raster map layers.
- 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.thin, Thins non-zero cells that denote linear features in a raster map layer.
- r.watershed, Calculates hydrological parameters and RUSLE factors.
- r.quantile, Compute quantiles using two passes.
- v.buffer, Creates a buffer around vector features of given type.
- r.surf.fractal, Creates a fractal surface of a given fractal dimension.
- v.sample, Samples a raster map at vector point locations.
- r.random.cells, Generates random cell values with spatial dependence.
- r.statistics, Calculates category or object oriented statistics.
- v.to.rast3, Converts a vector map (only points) into a 3D raster map.
- i.cluster, The resulting signature file is used as input for i.maxlik, to generate an unsupervised image classification.
- v.segment, Creates points/segments from input vector lines and positions.
- r.rescale.eq, Rescales histogram equalized the range of category values in a raster map layer.
- r3.gwflow, Numerical calculation program for transient, confined groundwater flow in three dimensions
- r.resamp.bspline, Bicubic or bilinear spline interpolation with Tykhonov regularization.
- r.random.surface, Generates random surface(s) with spatial dependence.
- r.sim.water, Overland flow hydrologic simulation using path sampling method (SIMWE).
- 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.buffer2, Creates a raster map layer showing buffer zones surrounding cells that contain non-NULL category values.
- v.label, Creates paint labels for a vector map from attached attributes.
- v.lrs.label, Create stationing from input lines, and linear reference system
- r.li.richness, Calculates dominance's diversity index on a raster map
- i.fft, Fast Fourier Transform (FFT) for image processing.
- r.horizon, Computes horizon angle height from a digital elevation model. The module has two different modes of operation: 1. Computes the entire horizon around a single point whose coordinates are given with the 'coord' option. The horizon height (in radians). 2. Computes one or more raster maps of the horizon height in a single direction. The input for this is the angle (in degrees), which is measured counterclockwise with east=0, north=90 etc. The output is the horizon height in radians.
- i.eb.h_SEBAL01, Computes sensible heat flux iteration SEBAL 01.
- v.voronoi, Creates a Voronoi diagram from an input vector map containing points or centroids.
- r.to.rast3elev, Creates a 3D volume map based on 2D elevation and value raster maps.
- v.reclass, Changes vector category values for an existing vector map according to results of SQL queries or a value in attribute table column.
- v.lidar.edgedetection, Detects the object's edges from a LIDAR data set.
- r.resamp.stats, Resamples raster map layers to a coarser grid using aggregation.
- v.random, Generates randomly 2D/3D vector points map.
- i.latlong, creates a latitude/longitude map
- i.his.rgb, Transforms raster maps from HIS (Hue-Intensity-Saturation) color space to RGB (Red-Green-Blue) color space.
- r3.info, Outputs basic information about a user-specified 3D raster map layer.
- v.net.iso, Splits net to bands between cost isolines (direction from centre). Centre node must be opened (costs >= 0). Costs of centre node are used in calculation.
- v.proj, Allows projection conversion of vector maps.
- r.contour, Produces a vector map of specified contours from a raster map.
- r.resample, GRASS raster map layer data resampling capability.
- r.mfilter, Raster map matrix filter.
- r.describe, Prints terse list of category values found in a raster map layer.
- r.surf.random, Produces a raster map of uniform random deviates whose range can be expressed by the user.
- r.volume, Calculates the volume of data "clumps", and (optionally) produces a GRASS vector points map containing the calculated centroids of these clumps.
- v.mkgrid, Creates a vector map of a user-defined grid.
- r.sim.sediment, Sediment transport and erosion/deposition simulation using path sampling method (SIMWE).
- r.gwflow, Numerical calculation program for transient, confined and unconfined groundwater flow in two dimensions.
- v.db.select, Prints vector map attributes.
- r.proj, Re-projects a raster map from one location to the current location.
- r.li.edgedensity, Calculates edge density index on a raster map, using a 4 neighbour algorithm
- r.drain, Traces a flow through an elevation model on a raster map.

At the moment the following input and output types are supported by the GRASS Backend:

Mimetype | Input | Output |

image/tiff | Yes | Yes |

image/geotiff | Yes | Yes |

application/geotiff | Yes | Yes |

application/x-geotiff | Yes | Yes |

image/png | Yes | Yes |

image/gif | Yes | Yes |

image/jpeg | Yes | Yes |

application/x-erdas-hfa | Yes | Yes |

application/netcdf | Yes | Yes |

application/x-netcdf | Yes | Yes |

Mimetype | Schema | Encoding | Input | Output |

text/xml | http://schemas.opengis.net/gml/2.1.2/feature.xsd | UTF-8 | Yes | Yes |

application/vnd.google-earth.kml+xml | http://schemas.opengis.net/kml/2.2.0/ogckml22.xsd | UTF-8 | Yes | Yes |

application/dgn | - | - | Yes | No |

application/shp | - | - | Yes | No |

application/x-zipped-shp | - | - | Yes | Yes |

There is a demo WPS exposing GRASS processes available at:

http://geoprocessing.demo.52north.org:8080/wps/WebProcessingService