of Geographic Information and Decision Analysis, vol. 1, no. 2, pp. 151-157,
IDRISI for Windows 2.0
Slobodan P. Simonovic
Natural Resources Institute
and the Department of Civil Engineering, The University of Manitoba, Winnipeg,
Canada, R3T 2N2
|Name and Version of the Software
||IDRISI for Windows Version 2, March 1997
||Clark Labs for Cartographic Technology and Geographic
Clark University, 950 Main St., Worcester, MA 01610-1477
|Operating System Requirements
||Windows 3.X, Windows 95, Windows NT 3.5x or 4.0
Compatibility with OS/2 Warp, SoftPC, and WABI (not guaranteed)
||80386 and up; high-end 80486, or better, recommended
||4 Mb (8 Mb, or greater, recommended)
||15 Mb for program
33 Mb for tutorial exercise data sets
||8 bits minimum (15 bits optimal)
Ideal resolution 1024 X 768
||CD-ROM and 3.5 inch diskette
||English, French, Spanish, German, Russian, Chinese, and
|Technical Support Availability
||Telephone, fax, e-mail, and Internet
||Commercial US $990
Research/Non-Profit/Government US $695
Academic US $495
Full-time student US $247.50
Elementary/secondary school US $100
Student starter US $95
Site license US $2,475 (minimum 10 seat license)
|General Software Capabilities
||AHP for weights
selection in a multi-criteria evaluation
multi-objective ordering of cells
and Bayesian decision making
weight of evidence
Time Series Analysis
through differencing and ratioing
principle components analysis
agency data formats
|Useful Web Sites
||IDRISI Project Home Page: http://www.idrisi.clarku.edu/doc_new/01home/01home.htm
IDRISI for Windows WWW Tutorial: http://www.edvz.sbg.ac.at/geo/idrisi/wwwtutor/tuthome.htm
The following table presents ratings for the software in eight categories:
GIS, mapping, decision analysis, modeling, image processing, multimedia,
user-friendliness, and ability to customize the software.
The rating system is as follows:
1=POOR: Nonexistent, incomplete,
inadequate, buggy, etc.
2=FAIR: Difficult to use,
quirky, not organized, not intuitive, etc.
3=GOOD: Sufficient capabilities,
organized, satisfactory presentation, no bugs, relatively easy to learn,
4=VERY GOOD: Solid fundamental
capabilities and more, easy to learn and use, nicely organized, good presentation,
and impressive capabilities, nice surprises, very easy to learn and use
features, outstanding organization and presentation, etc.
|Formal Decision Analysis Capabilities
|Image Processing Capabilities
IDRISI software is named after the Spanish geographer Idrisi (born in
1099) who devoted most of his life to the goal of preparing a geographic
survey of the world. Following his ideas, this software package is probably
one of the major steps in contemporary times towards assisting professionals,
academics, and others involved with spatial data analyses all over the
world. Created and distributed since 1987 under the spirit of democratization
of technology, IDRISI is used today in more than 130 countries, available
in five languages, and supported by ten resource centers (in Austria, United
Kingdom, Hungary, Brazil, China, Costa Rica, Poland, Russia, Spain, and
The IDRISI system consists of a main interface program equipped with a
menu and toolbar system and over 150 program modules that provide facilities
for the input/output (I/O), display, and analysis of spatial data. The
interface is very friendly and similar to many Windows-driven applications.
The main screen is divided into several regions. The menu system is accessible
at the top of the application window and can be activated with the mouse
or keyboard. Just below the menu is the tool bar, a set of buttons that
represent either a program module or an interactive operation. At the bottom
of the screen is the status bar that provides information about program
operation. IDRISI contains an extensive on-line context sensitive help
that can be accessed in a variety of ways. Most of IDRISI functions have
their own window. By double-clicking with the mouse on any input entry
box, available files with input data can be displayed in list form and
then selected with the use of mouse operations. This version of IDRISI
has a powerful, extended cursor inquiry which can be activated through
a display preferences dialog box. Extended cursor inquiry is activated
by specifying a group of images associated in a new display preference
dialog. Whenever cursor inquiry is used with any member of a group, a special
window opens listing a table of values for all members of the group. Values
can be displayed in the form of a graph, too.
IDRISI is a professional
geographic information and image processing system. It is one of the largest
raster-based microcomputer systems on the market which integrates the use
of both vector and raster data layers. The system provides very good facilities
for geographic analysis and environmental modeling. A friendly user interface,
and good map composition and display systems allow access to over 150 analytical
modules. IDRISI has pioneered the development of special tools for GIS-based
multi-objective decision making, uncertainty management, and risk assessment.
Windows can be easily customized
using numerous options related to the title, layer frames, scales, legends,
text frames, logo, etc. Palette modification and legend caption editing
are interactive. Automatic display of analytical functions is available.
Automatic display causes the results of analytical operations to be displayed
after the operation has been completed. The system estimates whether the
data should be considered as qualitative or quantitative and use the appropriate
palette and legend options.
IDRISI supports data input
from three main sources: (a) digitizers, scanners, and global positioning
systems; (b) import of pre-existing data in IDRISI format; and (c) import
and conversion of data in commonly available non-IDRISI file formats (Arc/Info
files or satellite imagery). TOSCA, a DOS-based digitizing package, is
no longer supplied with the IDRISI system. However, a new Windows-based
digitizing and editing package is under development. IDRISI can import
data in a large number of formats. Also, IDRISI can work with seven data
forms: ASCII integer; ASCII real; byte binary; binary integer; binary real;
packed byte binary; and packed binary integer.
Probably one of the biggest
additions to Version 2 is the printer workshop facility that provides
a very good interface between IDRISI and printers supported by a Windows
driver. The importance of this addition is demonstrated by making a copy
available free of charge to all IDRISI users (even users of Version
1) via the IDRISI web site.
Equally important is the
first attempt of multimedia enhancement through media viewer. This
feature offers animated displays of time-series images and video clips,
and audio enhancements with the playing of sound files (.wav). This is
a 32-bit application and requires Windows 95 or Windows NT operating system.
The main thrust of the IDRISI system is decision support. Therefore, Version
2 has expanded into the area of classification of remotely sensed images.
Within this version, a set of traditional classifiers has been extended
by the soft classifiers based on fuzzy sets. New image processing capabilities
are definitely beyond the expertise of this reviewer, however it is obvious
that IDRISI Version 2.0 continues to improve the image processing capabilities
by adding tools capable of such tasks as radar data analysis and accurate
classification of images in dynamic landscapes.
The IDRISI system allows powerful and easy geographic analysis. Five categories
of tools are available to users for performing database queries, map algebra,
distance operations, context operations, and statistical analysis. Analyses
can be automated with the use of IDRISI macros. I was quite impressed with
the database workshop. With this tool, the tasks of creating, opening,
editing, and modifying databases was very easy (especially if the user
possesses some experience with other database management software). This
tool makes the use of SQL queries rather easy, and provides the ability
to perform powerful database queries. One of the most impressive features
of database workshop is the ability to link the database to a map
composition. This provides the user with the power to perform interactive,
geographic inquiry and exploration.
Also, Version 2 provides
an image calculator, a mathematical modeling tool that lets the
user enter a model as a full, algebraic equation. Most map algebra and
database query operations can be executed from this calculator-like interface.
The IDRISI Project's commitment from 1987 has been to provide a very strong
spatial decision support system. Version 2 continues the tradition by adding
uncertainty management and decision strategy analysis to the already substantial
set of tools for multi-criteria decision analyses. Very nice changes have
been made to the fuzzy tool for evaluation of the fuzzy membership
values. A user can now define membership function options and select the
output format. New procedures together with older capabilities provide
the means for straightforward suitability analysis, which has application
in a number of areas, such as ecology (for example, habitat suitability),
geology, environmental management, etc.
in Version 2 of IDRISI is achieved by one of three procedures. The first
involves Boolean overlay where all criteria are reduced to logical statements
of suitability and then combined by means of one or more logical operators
such as intersection and union. The second is known as weighted linear
combination where continuous criteria are standardized to a common numeric
range, and then combined by weighted average. The third option is known
as ordered weighted average which has the ability to offer a complete spectrum
of decision strategies along primary dimensions of the degree of tradeoff,
and the degree of risk aversion in the solution.
Uncertainty management is
supported by a group of new procedures for weight of evidence modeling,
including evaluation of multiple hypotheses with BAYES and a Dempster-Shafer
analysis of evidence with BELIEF. The role of this latter module is in
the development and revision of a knowledge base concerning a set of hypotheses.
A revision of multi-dimensional
choice procedure now allows up to four levels of abstraction on either
the most or least suitable choice from a set of alternatives. For each
pixel the best choice, the next best choice, the next next best choice,
and so on, can be estimated. For example, in multi-criteria modeling of
vulnerability to drought, the magnitude of this vulnerability from location
to location can be estimated. These same criteria can then be used to determine
primary, secondary and tertiary causes of vulnerability for each pixel.
IDRISI for Windows Version 2 has improved the time-series analysis capability
considerably by adding a 32-bit version of the TSA tool for long
time series (up to 256 input images) principal components analysis. In
the new version, development of transition models is facilitated by the
addition of multireg and logireg tools for multiple regression
analysis and logistic regression analysis, respectively. These models can
help in a variety of applications, such as land use analysis with the goal
of identifying the probability of change based on a multivariate model.
The IDRISI system is distributed with the following: (a) a user's guide;
(b) a quick reference; (c) an installation guide; (d) twelve 3.5" disks
or one CD-ROM; (d) a book of tutorial exercises; and (e) selected inserts,
news, etc. The installation process was very smooth (I was replacing IDRISI
for Windows Version 1 with Version 2) and efficient. In this regard, the
installation guide is quite clear and easy to follow. The quick reference
booklet could be useful, but I did not yet feel the need to use it - possibly
because of my previous experience with the IDRISI system. The user's guide
is a comprehensive document with the majority of sections written for advanced
users. My recommendation to beginners is that they not look at the advanced
topics before obtaining a strong familiarity with GIS and the available
GIS tools. On the other hand, the tutorial guide is recommended for everyone.
The guide itself, and the set of tutorial data sets provided with the software
are of great help in mastering this powerful system. The tutorial contains
17 introductory exercises and 15 advanced exercises. These exercises gradually
increase in complexity, and their structured development of material from
exercise to exercise provides an essential step in understanding spatial
analysis, learning to use GIS, and mastering the available software tools.
Additional learning tools are available through the efforts of the Austrian
Resources Center, which created a web-based tutorial (web site address
I did not use the available
technical support. However, the options are impressive (phone, fax, e-mail,
web site, resource centers), and the technical support is free for the
first 60 days.
4. Overall Impressions
IDRISI for Windows Version 2 builds on the strengths of previous IDRISI
developments in the area of spatial decision support. The addition of two
new directions, uncertainty analysis and decision strategy analysis, make
an important technological contribution. The developers are forging ahead
on important paths for the future of GIS applications. Furthermore, tools
previously incorporated into IDRISI for Windows correspond with ongoing
developments in the field of GIS (dynamic modeling, multimedia, etc.).
Thus, IDRISI as a product for PC environments has a very strong position
in the marketplace.
IDRISI for Windows Version
2 is a professional-level geographic information and image processing system
for variety of users. It can be used with equal success in the private
sector, government agencies, research institutions, academia, and elementary
or secondary schools.
Judging based on this product,
my opinion is the IDRISI development team is successful in moving forward
with the goal of democratization of technology.