GRASS GIS 6.2.4cvs 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

vector commands:
v.buffer Create a buffer around features of given type (areas must contain centroid). Creates topology for GRASS vector data. Build polylines from lines.
v.category Attach, delete or report vector categories to map geometry.
v.centroids Adds missing centroids to closed boundaries
v.clean Toolset to clean vector topology
v.convert.all v.convert.all
v.convert Imports older versions of GRASS vector maps.
v.db.addcol Adds one or more columns to the attribute table connected to a given vector map
v.db.addtable Creates and adds a new attribute table to a given layer of an existing vector map.
v.db.connect Prints/sets DB connection for a vector map to attribute table
v.db.droptable removes existing attribute table of a vector map
v.db.reconnect.all Reconnect vectors to a new database Print vector attributes
v.db.update Allows to assign a new value to a column in the attribute table connected to a given map
v.delaunay Create a Delaunay triangulation from an input vector map containing points or centroids.
v.digit Interactive editing and digitization of vector maps.
v.dissolve Dissolve boundaries between adjacent areas sharing a common category number or attribute
v.distance Find the nearest element in vector 'to' for elements in vector 'from'. Various information about this relation may be uploaded to the attribute table of input vector 'from' or printed to stdout
v.drape Convert 2D vector to 3D vector by sampling of elevation raster. Default sampling by nearest neighbor
v.external Create a new vector as a read-only link to OGR layer. Available drivers:
v.extract Selects vector objects from an existing vector map and creates a new map containing only the selected objects. If 'list', 'file' and 'where' options are not specified, all features of given type and layer are extracted, categories are not changed in that case.
v.extrude Extrudes flat vector object to 3D with defined height
v.hull Uses a GRASS vector points map to produce a convex hull vector map Convert GRASS ascii file or points file to binary vector. Create new vector (points) from database table containing coordinates. Converts files in DXF format to GRASS vector file format. Import of E00 file into a vector map. Upload Waypoints, Routes, and Tracks from a Garmin GPS receiver into a vector map. Imports US-NGA GEOnet Names Server (GNS) country files into a GRASS vector points map Import waypoints, routes, and tracks from a GPS receiver or GPS download file into a vector map. Import Mapgen or Matlab vector maps into GRASS. Convert OGR vectors to GRASS. Available drivers: Create a new vector from current region. Converts a GRASS site_lists file into a vector file. Outputs basic information about a user-specified vector map layer.
v.kcv Randomly partition points into test/train sets.
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
v.label Create paint labels for GRASS vector file and attached attributes.
v.lidar.correction Correction of the v.lidar.growing output. It is the last of the three algorithms for LIDAR filtering
v.lidar.edgedetection Detect the object's edges from a LIDAR data set.
v.lidar.growing Building contour determination and Region Growing algorithm for determining the building inside
v.lrs.create Create Linear Reference System
v.lrs.label Create stationing from input lines, and linear reference system
v.lrs.segment Create points/segments from input lines, linear reference system and positions read from stdin or a file
v.lrs.where Find line id and real km+offset for given points in vector map using linear reference system
v.mkgrid Creates a (binary) GRASS vector map of a user-defined grid.
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 layer. Allocate subnets for nearest centres (direction from centre). Centre node must be opened (costs >= 0). Costs of centre node are used in calculation Network maintenance. Split net to bands between cost isolines (direction from centre). Centre node must be opened (costs >= 0). Costs of centre node are used in calculation Find shortest path on vector network. Create a cycle connecting given nodes (Traveling salesman problem). Note that TSP is NP-hard, heuristic algorithm is used by this module and created cycle may be sub optimal. Create Steiner tree for the network and given terminals. Note that 'Minimum Steiner Tree' problem is NP-hard and heuristic algorithm is used in this module so the the result may be sub optimal.
v.normal Tests for normality for points.
v.out.ascii Convert a GRASS binary vector map to a GRASS ASCII vector map
v.out.dxf Exports GRASS vector files to DXF file format.
v.out.ogr Convert to one of the supported OGR vector formats.
v.out.pov Convert to POV-Ray format, GRASS x,y,z -> POV-Ray x,z,y
v.out.vtk Convert a GRASS binary vector map to VTK ASCII output
v.outlier Removes outliers from vector point data
v.overlay Overlay 2 vector maps.
v.parallel Create parallel line to input lines.
v.patch Creates a new binary vector map layer by combining other binary vector map layers.
v.perturb Random location perturbations of GRASS vector points
v.proj Allows projection conversion of vector files.
v.qcount indices for quadrat counts of sites lists
v.random Randomly generate a 2D/3D GRASS vector points map.
v.rast.stats Calculates univariate statistics from a GRASS raster map based on vector polygons and uploads statistics to new attribute columns
v.reclass Changes vector category values for an existing vector map according to results of SQL queries or a value in attribute table column. Reports geometry statistics for vectors.
v.sample Sample a raster file at site locations
v.segment Create points/segments from input lines and and positions. Select features from ainput by features from binput
v.split Split lines to shorter segments. Bicubic or bilinear spline interpolation with Tykhonov regularization Surface interpolation from vector point data by Inverse Distance Squared Weighting. Spatial approximation and topographic analysis from given point or isoline data in vector format to floating point raster format using regularized spline with tension. Load values from vector to database. In uploaded/printed category values '-1' is used for 'no category' and 'null'/'-' if category cannot be found or multiple categories were found. Create points along input lines. Converts a binary GRASS vector map layer into a GRASS raster map layer. Converts a binary GRASS vector map (only points) layer into a 3D GRASS raster map layer.
v.transform Transforms an vector map layer from one coordinate system into another coordinate system.
v.type Change the type of geometry elements.
v.univar Calculates univariate statistics for attribute. Variance and standard deviation is calculated only for points if specified Calculates univariate statistics on selected table column for a GRASS vector map
v.vol.rst Interpolates point data to a G3D grid volume using regularized spline with tension (RST) algorithm
v.voronoi Create a Voronoi diagram from an input vector map containing points or centroids.
v.what Queries a vector map layer at given locations
v.what.rast Uploads raster values at positions of vector points to the table
v.what.vect Uploads vector values at positions of vector points to the table

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