GRASSLinks: The Public Access GIS
Entry ID: GRASSLinks
Abstract: GRASSLinks is an interactive, real-time Web GIS application
developed by REGIS based on the U.S. Army Core of Engineer's
GRASS GIS software. GRASSLinks allows for sophisticated GIS
functionality, such as display, query, reclass, overlay, and
buffer, to geospatial data in GRASS format via the use of a
World Wide Web browser, such as Netscape. In order to be able to
use GRASSLinks to provide Web ... access to data, that data must
first be in a GRASS file format and all data must be in the same
projection and coordinate system.
GRASSLinks seeks to serve two communities of geodata users:
those who do not have GIS capabilities and those who do. The
first group is comprised of users with access to the internet,
but who do not have their own GIS capabilities. Mosaic is
available on most platforms and is currently in the public
domain. A Mosaic-based "point and click" interface ensures
that users need not know any of the specific commands normally
required to access a GIS.
The second group served by GRASSLinks includes land use planning
and management agencies. Land use planning decisions frequently
require the cooperation of multiple agencies. Or, different
agencies may need to use the same information for their own
purposes. GRASSLinks can be an important part of creating a
distributed database network. Historically, each agency would
have its own database, and then continually maintain their own
data as well as data obtained from other sources. A new model of
data sharing would be for each agency to maintain data for which
they are responsible, and then access other data over the
network as needed. This model can be applied to non-governmental
organizations, research groups schools, or commerical entities.
Tools included in GRASSLinks:
1) Map display: images are created of raster, vector, and sites
a) The vector and sites drawing colors, map region, and image
resolution of the image can be specified.
b) Zoom in, zoom out, or pan across an image to create new
images which can also be navigated ad infinitum.
c) query of map display -- the value of the displayed raster
data and the coordinates of the selected point are queried by
clicking with the mouse on the image
2) Aerial photography display: A map of the area depicts the
location of aerial photo stations. Clicking on a station brings
up the appropriate photograph.
3) Metadata display: the information describing the map layers,
their source, dates, accuracy, etc., is available for the data
4) Area calculations: The Areal extent of mapped categories, or
the overlap of categories between two maps is calculated (e.g.,
wetlands acreage by county)
5) Reaggregation: categories of a data layer can be aggregated
together to create a new map (e.g., a map of more general
6) Buffering: Successive bands of known width around specified
map categories, create a new map showing proximity to features
(e.g., a riparian zone, or a buffer around drinking wells).
7) Combining maps: A new map can be produced that shows areas of
overlap between categories in different maps (e.g., existing
wetlands within areas zoned for development).
8) Data layer transfer: the GRASS format data layer can be
downloaded for personal use.
[Summary provided by REGIS]
ISO Topic Category
Quality REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF
ANY, PROVIDED HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO
OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
Access Constraints GRASSLinks is a perl script and requires local access to
perl. GRASSLinks has been tested under Digital Unix 4.0. It
should run on any UNIX system or any system that has Perl 4.x or
5.x installed (though it will probably need more tweaking on a
non-Unix system that what is detailed herein). You must have
the software GRASS accessible ... from the same server that is
running GRASSLinks and you must have some existing GRASS raster,
vector and sites files. You must have a web htdocs directory in
which to locate GRASSLinks html files and helper files. You
must have the ability to run cgi scripts on your web server.
You will probably need access to super-user status on your
system or the person with this status. You will need to install
the free netpbm/pbmplus ppm programs which can be downloaded off
the web. GRASSLinks utilizes public domain software, GRASS,
created by the US Army Corps of Engineers. We assume that anyone
installing GRASSLinks already has experience using GRASS.
Use Constraints Grasslinks 3.1 Copyright (c) 1998 The Regents of the University
of California (Regents). Created by Patricia Frontiera, Susan
Huse, James Ganong, and Kenn Gardels, Center for Environmental
Design Research, University of California, Berkeley. GRASSLinks
3.1 is based on a work created by Susan Huse at the University
of California, ... Berkeley.
Redistribution and use of GRASSLinks 3.1 in source and binary
forms, with or without modification, are permitted provided that
the following conditions are met: 1.Redistributions of source
code (with or without modification) must retain the above
copyright notice, this list of conditions and the following
disclaimer. 2.Redistributions in binary form (with or without
modification) must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the
documentation and/or other materials provided with the
IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT,
INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE
AND ITS DOCUMENTATION, EVEN IF REGENTS HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
Creation and Review Dates