GRASS 4.1 Release Information

Released Spring 1993 (4.1) / Jan. 1995 (4.1.5)

GRASS 4.1 is available on the Internet FTP server. It is also still available on the USA-CERL Internet FTP server (IP address The GRASS Download Area is also available.

Note that GRASS 4.1 is available solely for reference purposes.

The major new capabilities in GRASS 4.1 include: * dbtools: a GRASS-DBMS link to Informix
* XGRASS: an X Window System/Motif based Graphical User Interface to GRASS * surface interpolation and modeling capabilities * enhancements to SG3D: 3D visualization tools for the Silicon Graphics platform * new tools for projection use/translation

Installation Guide

The Installation Guide discusses many features and procedures new to the GRASS 4.1 release. Please read the entire document carefully before beginning installation. Main and alpha programs are automatically compiled as part of the installation process.

Programmer’s Manual

Information about new digitizer configurations can be found in Chapter 21. The GRASS 4.0 procedures, “Writing a Digitizer Driver,” are still available in Chapter 24 for those who wish to use the GRASS 4.0 version of v.digit, now renamed v.digit2.

User’s Reference Manual

The GRASS 4.1 User’s Reference Manual is divided into the following sections:

  • Main programs and programs in alpha testing
  • Shell script programs
  • Index of contributed programs
  • Descriptions of program formats

The manual includes a section of hardware- and software-specific programs and supporting information (e.g., XGRASS, SG3d, and Intergraph). Main and alpha programs are combined in the same chapter in the manual and are distinguishable by the designation or in the header section of each man page. The index of contributed code lists program names and, in some cases, program descriptions. More complete documentation is presented on-line in the src.contrib directory. Because the CERL Office of GRASS Integration (OGI) does not support or test the contributed code or documentation, users are advised that the programs may not operate as expected and there may be no consistency in documentation format.


One new TIGER tutorial is available with the GRASS 4.1 release as well as six new contributed programs for the TIGER/Census data (,,, v.apply.census, and The suite of programs described in the new tutorial, “Importing TIGER/Line Maps and STF1 Data in GRASS”, provides the means to import TIGER/Line dnd STF1 data in GRASS without using a database manager.

Main and Alpha Program Enhancements in GRASS 4.1

d.measure - Program works in both UTM and lat/lon coordinate system.

g.region - An additional parameter, 3dview, is available when in non-interactive mode. It makes current region settings the same as those in the named 3dview file, which holds the region that was current when the 3dview was saved.

i.cluster - The program can be run interactively or non-interactively.

m.dem.extract.html - Allowable input may now be either a file or a tape.

m.tiger.region.html - Now works with version 4 files.

r.cost - Increased execution speed and added capability for the rapid construction of hydrographs.

r.slope.aspect.html - Additional parameters which allow users to specify slope format (degrees, percent): zfactor, a multiplicative factor to convert elevation units to meters; and min_slp, the minimum slope for which aspect is computed.

r.thin - The code now implements the thinning algorithm described in “Analysis of Thinning Algorithms Using Mathematical Morphology” by Ben-Kwei Jang and Ronald T. Chin. The authors define the thinning process as “the successive removal of outer layers of pixels from an object while retaining any pixels whose removal would alter the connectivity or shorten the legs of the sceleton.”

v.spag - Program now stable enough to reside in main GRASS code. New parameter added for use in command line: -i, which removes existing identical lines. - Supports by converting line data to site data.

New Main and Alpha Programs in GRASS 4.1

g.setproj- Allows the user to create the PROJ_INFO and the PROJ_UNITS files to record the projection information associated with a current location.

i.gensig.html - A non-interactive method for generating input into i.maxlik.

i.gensigset - A non-interactive method for generating input into i.smap. - Creates imagery files from ERDAS files.

i.rectify2 - This imagery function rectifies an image by computing a coordinate transformation for each pixel in the image based on the control points created by the GRASS program i.vpoints. Provides second and third order polynomial rectification.

i.smap - An imagery function that performs contextual image classification using sequential maximum a posteriori (SMAP) estimation and multi-modal signatures (generated by i.gensigset). - Program extracts SPOT imagery from 9-track, half-inch tape. - An imagery function that extracts Thematic Mapper ™ imagery (fast format) from tape media.

i.vpoints - Identifies coordinate pairs of points from a vector map or keyboard entry and corresponding points in an image. Works with i.rectify and i.rectify2.

m.proj - Calculates conversion coordinates for geographic positions. - Produces color maps for output on a color hardcopy device or a graphics monitor. Output can include a raster map, any number of vector overlays, site data, text labels, and other map elements.

ps.icon - Allows the user to create and maintain icons which are used by to depict sites. - Produces an output file containing a PostScript program to produce hardcopy map products on system’s PostScript output device. Output can include a raster map, any number of vector overlays, site data, text labels, and other spatial data. - Allows the user to select the PostScript device for GRASS hardcopy output.

r.contour - Produces a binary vector map of specified contours from a raster map layer.

r.digit - Interactive tool used to draw and save vector features on a graphics monitor using a pointing device (mouse). - Allows creation of raster maps from an ascii polygon/line data file.

r.mask.points - Examines and filters lists of points constituting lines to determine if they fall within current region and mask and optionally an additional raster map.

r.median - Finds the median of values in a cover raster map layer within areas assigned the same category value in a user-specified base raster map.

r.mode - Finds the mode of values in a cover map within areas assigned the same category value in a user-specified base map. - Interpolation and topographic analysis from given site data to GRASS raster format using spline with tension.

v.alabel - Bulk labels unlabeled area features in a binary GRASS vector file.

v.digit - A new version of GRASS 4.0 v.digit.(The GRASS 4.0 v.digit has been renamed v.digit2) Upgraded so that it no longer requires drivers to be written for each digitizer supported. - A new version of GRASS 4.0 (The GRASS 4.0 has been renamed Capable of storing multiple attribute data from a USGS DLG file in a related text file that links back to a vector file in GRASS. - Imports transect data to a GRASS vector map. A transect is a line or an area, and a length (in meters or feet).

Other Information About GRASS 4.1

GRASS 4.1 programs name changes include i.median to i.quantize, to, Gen.tractmap to, d.p.labels to d.paint.labels and to r.weight2.

The programs,, and i.rectify.blk have been incorporated into

New contributed programs include d.linegraph, s.medp, f.acap, f.detail, f.econ, f.input, f.reach, f.wsurf, f.xsection, i.texture,, s.voronoi, v.autocorr,, v.reg, wrat and r.colors.paint.

© 1999-2002 GRASS Development Team