Choosing a GIS

COMPANY	2000	2001
ESRI	36	35
Intergraph	16	13
GE Network Solutions	7	7
Autodesk	6	7
Leica Geosystems (ERDAS)	2	6
MapInfo	6	6
IBM	2	5
SICAD	6	5
Logica	3	3
Other	11	14
GeoGraphix	3
Enghouse	2

Daratech reports that the largest market for GIS Software (in 2001) was the utilities industry (21%), followed by state and local governments, the telecommunications industry, and organizations involved in natural resource management.

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What licenses are available?

Many vendors offer free, time-limited, evaluation software. In addition, many vendors also offer student or site licenses. You may be able to strike a better deal by working collectively rather than individually. Check with other departments on your campus to determine what site licenses already exist. Some vendors will also make multi-campus license deals.

ESRI: evaluation, single, site, student

Idrisi (Kilimanjaro): single, site, and student

Manifold 6.0

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What teaching resources are available?

Teaching resources include tutorials, lecture notes, and labs. Most GIS will be packaged with tutorials; however, you will also find other material online.

ESRI’s ArcGIS is packaged with tutorials for ArcCatalog, ArcMap, ArcToolbox, and any extensions that you purchase. ESRI maintains resources for teaching GIS in higher education, which includes links to lab exercises.  For additional assistance with ESRI products, see:

• the companion web-site for Keith Clarke's introductory text, Getting Started with Geographic Information Systems, for lecture notes and laboratory exercises for ArcView 3.1 and ArcGIS 8.1.
• the CSISS GIS cookbook  for simple directions for common GIS tasks for ArcView and ArcGIS.

Idrisi Kilimanjaro is packaged with six tutorials that provide a resource for teaching generic concepts in GIS and for using Idrisi. Clark Labs also

• developed a series of workbooks through a memorandum of understanding with the United Nations Institute for Training and Research.
• maintains a bibliography of research related to Idrisi and raster GIS.
• maintains a resource for 'Analytic Notes'
• established fifteen international Resource Centers with a stated commitment to GIS education and research.

Manifold provides user manuals for its products that describe many GIS concepts and include several step-by-step examples. In addition, they host an online Manifold user-group.

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What datasets come with the GIS?

The data supplied with a product can be highly variable. You may be able to negotiate for data when you purchase.

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Are there independent reviews of software options?

Several web sources publish reviews of commercial GIS. Those noted below are illustrative and do not constitute endorsements of their views.  You will want to check for reviews that are more recent.

Intergraph GeoMedia

Review in Directions Magazine (Apr 21, 2003) by Paul Amos, The Wharton School, University of Pennsylvania

IDRISI Kilimanjaro

Review in GeoWorld (2004) by Eileen G. Ernenwein, Center for Advanced Spatial Technologies, 12 Ozark Hall, University of Arkansas

Review in Geo:connexion by Dr. Steve Carver, Lecturer, School of Geography, University of Leeds

MapInfo Professional 7.0

Review in Directions Magazine (Dec 12, 2002) by Paul Amos, The Wharton School, University of Pennsylvania.

Manifold 5.50

Review in Directions Magazine (Sep 18, 2002) by Paul Amos, The Wharton School, University of Pennsylvania.

Comment to Amos Review in Directions Magazine by Dimitri Rotow, Product Manager, Manifold.

Response to Comment in Directions Magazine by Paul Amos.

"How do I do that in ArcGIS/Manifold: Illustrating Classic GIS Tasks" an excellent resource edited by Dr. Arthur J. Limbo, Jr. It is made available through the Cornell University Library, DSpace Open Access Repository at
http://dspace.library.cornell.edu/bitstream/1813/165/1/review_final.pdf.

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How have GIS been evaluated in the past?

Comparative discussions often begin by defining GIS as a generic information processing system composed of functional parts. Waldo Tobler (1) offered an early definition along these lines when he described automated cartography as a generic "data processing system" with four functions:

1. data gathering
2. data storing
3. data manipulating
4. data using

In 1976, Roger Tomlinson (2) led a report that compared different GIS. The report began by defining GIS as composed of six subsystems:

1. management subsystem (primarily institutional, such as staffing and fiscal plans)
2. data acquisition
3. data input and storage
4. data retrieval and analysis
5. information output
6. information use

More than a decade later, Stephen C. Guptill edited a report entitled "A process for evaluating geographic information systems" (3) that was published by the US Geological Survey. The report is available on-line. Guptill identifies five components of a GIS:

1. user interface
2. database management
3. database creation
4. data manipulation and analysis
5. data display and product generation

Guptill then provides a very detailed checklist for specific functions related to each component that a GIS (at the time) may support. Many of these tasks are still relevant to current GIS platforms, despite the changes in GIS since the report's publication, such as the transition from workstation to desktop computing, and the proliferation of graphical user interfaces offered by most current GIS that reduce the technical expertise required to them.

More recently, Keith Clarke (4) defined six functional components of a GIS that might help guide the choice of a particular GIS:

1. gathering data
2. storing data
3. viewing data
4. managing data
5. retrieving data
6. analyzing data

The Clarke framework is used to discuss similarities and differences among five GIS packages. The selection of software is not an endorsement, but is instead based on the availability of licenses for evaluation within the time allotted for this overview.

ESRI ArcGIS (click here for some additional background)

MapInfo Professional 7.5 (release 7.8 now available)

Idrisi Kilimanjaro

Manifold 5.5 (release 6.0 now available)

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How can I gather data?

Gathering data may involve different tasks that involve

1. finding and retrieving geographic data via the Internet
2. creating and editing data from hardcopy maps or scanned images

In the first case, the geographic data you need may exist and you just need to find it. You should consider what tools the GIS includes to facilitate searching and retrieving data through the Internet. For instance:

• In ArcGIS (ArcMap), you can choose to 'Add Data from the Internet'. From the list of Internet servers, you can connect to the Geography Network Explorer, (replaced by ArcGIS Online) where you can search for geographic data by placename or bounding area and then display the data in ArcMap. You can also search by keyword. For instance, typing “census TIGER” will retrieve a list of census tract and available attribute data.
• ArcIMS is an ESRI product that lets you publish maps and data on the Internet. In ArcCatalog, you can connect to ArcIMS Internet servers and browse through the data available on them. You can work with data as a live service over the Internet, or you can export the data locally, so that you can work with the data offline.
• MapInfo provides a tool, called Web Map Service (WMS), which will allow you to use raster map images from servers that comply with the Open GIS Consortium specifications.

If the data you need are not available in a suitable digital form, you will have to create it by digitizing: converting features on a paper map into digital format.

• With most (but not all) GIS, you can digitize features from a paper map with a digitizing tablet
  • You will need additional hardware (digitizing tablet) and will need to know what drivers your GIS will support (e.g., WinTab)
  • You may also need to purchase additional software
    • Clark labs distributes a separate product, CartaLinx, that supports over 300 digitizing tablets. This software can digitize vector data for Idrisi, ArcView, ArcInfo, and MapInfo.
• Alternatively, you can scan a map and then create feature geometry through the GIS interface.
  • a GIS should provide tools to support geo-referencing of scanned images and on-screen digitizing of vector data, including tools to:
    • minimize errors while digitizing (by defining 'snapping' tolerances and modes)
    • correct errors of digitized data (by 'cleaning' geometry).

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How can I store data?

Storing data is closely related to the issue of geographic representation. While the availability of geographic data in digital form may expedite analyses with GIS, it also removes the question of how geographic phenomena should be represented, or modeled. "Data modeling" has been an important topic in GIScience (5) (6).

Importantly, GIS may differ in their support of particular data structures, providing more functions for either vector or raster data. You should be aware that a GIS might support storage but not analysis of raster data (a GIS may store raster images for display as a background image on a map, but not support thematic queries and spatial analysis for raster data). For instance:

• ArcGIS stores both vector and raster data. However, you will need an extension (spatial analyst) to perform spatial analysis on raster data. Without this extension, you will still be able to work with raster images, but primarily as backgrounds for visualization.
• With GeoMedia, you can store raster images and display them on maps, but analysis of raster data is limited relative to vector data.
• MapInfo Professional also emphasizes vector operations. You can also display raster images, and perform some raster analysis, such as calculate slope and hillshade for digital elevation models.
• Idrisi supports many different kinds of raster operations, and also supports many operations for vector data.
• Manifold supports both vector and raster data.

  GIS will also use different formats to store data. The particular format used to store data can influence the potential use of the data, both for management and analysis tasks.

ArcGIS stores data in a number of different ESRI formats:

• ESRI's shapefile format is published and open. The shapefile is a set of related files and may contain additional attribute tables.
• ESRI's coverage format is proprietary. As a vector format, the coverage consists of a set of related files for primary features (such as arcs, nodes, polygons, and label points) and secondary features (such as tics, map extent, links, and annotation). Associated feature attribute tables describe and store attributes of the geographic features. Importantly, coverages store topology and are the inputs for many analytic functions in ArcGIS.
• ESRI stores raster data as GRID files, but again, you will need the spatial analyst extension to perform spatial analysis with raster data.
• The geodatabase is a more recent format from ESRI. With ArcGIS 9, the geodatabase now also supports raster.

MapInfo stores all data, whether textual or graphic, as tables (.tab file).

• Each table is a group of MapInfo Professional files that constitute either a map file or a database file.
• All MapInfo Professional tables have at least two files. The file with a .tab extension is a small text file that describes the file format containing your data. The file with .DAT, .WKS, .DBF, or .XLS extensions contain your tabular data. For raster tables, the equivalent extensions might be .BMP, .TIF, or .GIF.
• If your data already includes graphic objects, you will find two more files. The file with a .map extension describes the graphic objects, while the .id suffix is a cross-reference file that links the data with the objects. (For a Microsoft Access table, there will also be a file with .aid suffix that associates the table instead of an .ID file. This file links the data with the objects for a Microsoft Access table).

Idrisi stores both raster and vector data in IDRISI formats, called Image file (.rst) and Vector files (.vct).

With Manifold, you store and use both vector and raster data as components of a project (see 'viewing data').  A Manifold project is called a .map file format. You must import the geographic data file into a .map, which copies the data into the project file. For example, if you import a 10MB .bmp image into a project, the project .map file will increase in size by 10MB. However, you can also avoid copying data in three ways: (1) by linking tables into the project from an external database, (2) by linking drawings from an external geocoded database table, and (3) by using Enterprise Edition, which keeps all project components in a remote Enterprise server.

You should also be aware of the issue of data interoperability, which at the very least involves the ability to convert or directly use different data formats.

Some publicly available software for spatial analysis, such as GeoDa, and CrimeStats, use ESRI shapefiles for input. If you do not select an ESRI product, you will want to make sure that that your GIS can export and import shapefiles. GeoMedia, MapInfo, IDRISI, and Manifold all do.

One strategy for making data interoperable is to provide conversion tools. Thus, interoperability is a transformation function: input–convert–output. It results in the output of a new file.

ArcGIS provides graphical interfaces to convert data into ESRI formats. In ArcToolbox, you select functions to convert many public and proprietary formats.

Idrisi also provides graphical interfaces for data conversion.

With MapInfo, you can use data that was created in other file formats, including Microsoft Access, Microsoft Excel, dBASE DBF, ESRI Shapefiles, Raster Image, Grid Images, ASCII Delimited Text, Lotus 1–2–3, and several remote databases (Oracle, Informix, SQL Server, etc.). MapInfo Professional will create a table structure for the imported data based on the type of file that it is, and this table does not alter the original file.

With GeoMedia, you can access data in a number of formats without outputing a converted file format. You can also export queried data in various formats, including ESRI shapefiles, MicroStation design files (.dgn), MapInfo Interchange files, SQL server spatial database, Oracle Object model database, and AutoCAD.

With Manifold, you can import and export many different files as components of a Manifold project (.map file).

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How can I manage data?

A GIS should include common tools for data management tasks, including

• manually editing vector data , including "snapping" and "cleaning"
• geocoding attribute data, such as by address matching or creating geometry for the x and y coordinates of a text file
• defining and transforming projections

Additionally, most GIS use some variation of a "project" or "workspace" to organize and save work.

ArcGIS differs by providing an application, ArcCatalog, to manage geographic data independently of a particular project (ArcMap manages data within the map project, as discussed below). ArcCatalog uses a "filing cabinet" metaphor for data organization that resembles Windows Explorer. Data files are stored within "folders" in a hierarchical structure. Using ArcCatalog, you can browse, explore, view, search geographic datasets, and examine metadata. You can also access ArcToolbox and perform many data management tasks, such as define projection or alter tabular structure (field definitions).

GIS may differ with respect to how data are managed by projects, which influences the portability and storage size of project files.

• In some GIS, a project file contains links to data, rather than copies of the data.

• In ArcGIS, a project or workspace is called a "map". You access map files with ArcMap, and they are saved with an .mxd extension. The map organizes and saves geographic data, tables, charts, and layouts that are based on links between the map file and the geographic data files. This can give you some headaches when you manage or share your map files. You may find a layer missing from your map because you have moved it in ArcCatalog, and ArcMap can no longer find it. Similarly, if you want to give a colleague a copy of your map file, you will need to copy the relevant geographic data, and make sure that ArcMap knows which directory holds the data. ArcMap does allow you to store 'relative paths' for a project, which links the map to partial paths (such as csiss/SPACE) rather than full paths (C://gis/csiss/SPACE). This is very useful for data sharing.

• GeoMedia's project is called a "GeoWorkspace". It is an application file that contains objects, such as named legends, queries, and warehouse connections. You use a template to create a GeoWorkspace (.gwt file). A template is a file that provides the objects that will be used to produce a new GeoWorkspace. Warehouse connections link the GeoWorkspace to a database that stores geographic data. The warehouse stores datasets within their native formats, such as ESRI shapefiles, Access databases, Oracle databases, etc.

• MapInfo manages data within a "workspace". A workspace file (.wor extension) contains a list of all the tables, windows, and settings you have been using and the actions MapInfo Professional needs to re-create your mapping session. To save your work, you can use the "Workspace Packager" tool to create a copy of your current workspace in a new folder, and copy all the data referenced by the workspace in the same folder. Using this tool, the workspace looks to these internal references to find the data and .tab file, so you can open this workspace no matter where you have moved or copied that folder, even if you move it to a different computer.

Alternatively, the project file may contain copies of the data, which makes the project file easy to share, but also requires more storage space.

• Manifold manages data with a .map file (Manifold Project). Manifold does not store links between a "project" and the geographic datasets that are used by the project. Instead, Manifold copies the datasets and stores them in a .map file. The help file justifies this by stating that (1) disk space is cheap, (2) this simplifies exchanging .map files among Manifold users, and (3) if you want to minimize storage issues, then you can purchase the Enterprise Edition that stores all data on a centralized server. To move individual components between .map files, you must open the two projects simultaneously, copy the component from one .map, and paste it in the other. Or you can export the component into another format.

• A .map file automatically compresses the data in the project using techniques that are similar to 'zip' compression utilities. The compression ratio depends on the types of data (components) that are in the .map file. Compressed .map files will automatically be decompressed when loaded into Manifold. Compression does require additional time when opening and saving .map files, though if you have a lot of free disk space, you can turn off the automatic compression to speed loading and saving files. Compression also requires disk space, because compressed .map files are first decompressed to a temporary file and then loaded into Manifold (a 20 MB compressed file may decompress into a 100 MB temporary file).

A GIS may also differ by how it manages requests for information.

• In GeoMedia, you define "filters" that query data by location or attribute, and also perform some analysis. Filters do not create new data files, but rather the filters themselves are stored. In other words, GeoMedia stores your access and processing of existing datasets, rather than the data structures that result from your requests. This reduces file management issues: you do not have to keep track of a bunch of data files created during your analysis. In addition, this helps ensure currency in information retrieval, as changes to the "connected" datasets will be reflected in the "filtered" map.

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How can I manage metadata?

Support for metadata is increasing in GIS. For instance:

• In ArcGIS, ArcCatalog provides direct access to metadata from geographic data files in different standards for documentation, including the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata. Metadata is stored as .xml. You can also customize a new format that may not be as detailed as the FGDC but still be adequate to serve your needs.
  • Some metadata is created automatically. In ArcGIS, metadata consists of "properties" and "documentation":
    • Properties, such as the extent of a shapefile's features, are automated by ArcCatalog from the data.
    • Documentation is descriptive information entered manually
• MapInfo provides a tool, called the "Table Manager" for accessing metadata in your workspace. This allows you to view and modify existing metadata, load a template to populate with metadata, and export metadata into FGDC standards. MapInfo Professional has a MetaData Browser that allows you to search data clearinghouses on the web for data products.
• IDRISI maintains a file for each map layer that documents the internal storage format, legend information, and the nature of the reference system to which the data are registered.
  • For image layers, these files have a ".rdc" file extension, while for vector layers they have a ".vdc" extension. For example, an image layer named "soils" will consist of two data files – an image data file named "soils.rst" and its associated documentation file named "soils.rdc". Similarly, a vector layer named "districts" will consist of two data files named "districts.vct" and "districts.vdc".
  • This documentation file then provides a summary through the metadata module for raster, vector, attribute values, and reference files.

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How can I view data?

Viewing data with a GIS often begins with the concept of a "project" or "workspace", discussed above, that organizes maps, tables, charts, layouts, scripts, and other elements of a GIS application.

While there may be more similarities than differences here, you may consider the following questions when choosing a GIS:

• can you create more than one "layout" for a project?
• can you define export formats and image parameters for layouts?
• can you create graphs and reports from project data?
• how can you classify thematic data (e.g., natural breaks, equal interval, quartile, defined interval, standard deviation, user-defined)?
• how can you process raster images (e.g., linear enhancement)?
• can you embed or link objects between GIS projects and other applications (such as linking a map to a slide)?
• can you create 3D or interactive representations (such as a fly-by over terrain)?
• can you publish maps and other GIS elements on the Internet for viewing with ordinary browsers?

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How can I retrieve data?

There are three basic operations to retrieve data that most GIS will support:

1. select manually, by clicking on a map object or table element
2. select by location, by creating some sort of shape and 'cutting' through map layers
3. select by attribute, by creating a logical request, most commonly with Structured Query Language (SQL)

You may want to consider the following when choosing a GIS:

• What spatial relationships can be used to define a selection? For instance:
  • "are crossed by the outline of"
  • "are intersected by"
  • "are within a distance of"
  • "have their center in"
  • "are completely within"
  • "are completely contained by"
  • "share a line segment with"
  • "touch the boundary of"
  • "are identical to"
  • "contain"
  • "are contained by"
• Is there a wizard and debugger to facilitate the construction of SQL queries?
  • For example, Manifold provides a window to write an SQL statement, but you will need to know the syntax of SQL, and the help menu is useful. To debug your statements, you will need to purchase Manifold Professional with debugger (which is an extra $50).

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How can I analyze data?

There are two analytic concepts commonly supported by GIS packages

1. Spatial overlay: analysis of layers
2. Spreadsheet functions: attribute calculations

While these are both common, some GIS go much further. Here are some questions regarding analysis that you may wish to consider when choosing a GIS:

• What kinds of analytic operations does the GIS support?
  • For instance, Idrisi includes analytic modules for GIS Analysis, Modeling, and Image Processing. These include:
    • Distance operations: concepts include diffusion, friction, force, path
    • Context operations: classifiers by neighborhood, filter, vista, flow (watershed and supply/demand)
    • Statistics, including modules to facilitate data movement to SPLUS
    • Decision support tools
    • Change analysis – including analysis of time series and simulation of change (cellular automata)
    • Surface analysis – including modules for interpolation, geostatistics, topographic ratios, and feature extraction.
• Is there a "macro" tool that helps connect a sequence of GIS operations?
  • For instance, ESRI's model builder provides a means to construct macros for multi-step analysis operations.
• How can the analytic functions of the GIS be extended?
  • For instance, ESRI offers many extensions, such as Spatial Analyst and Image Analyst, which expand the available analytic tools and allow you to manipulate and analyze raster datasets. (Again, you will have to purchase these extensions separately
  • You can also extend many ESRI applications with publicly available scripts.

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Summary

• Be clear about your purposes and goals for acquiring a GIS, as these will influence what software package may be most appropriate
• Test-drive trial versions
• Shop for licenses collectively and negotiate both for license and supplements, such as data
• Use Web resources to locate teaching materials
• In terms of functionality,
  • some GIS may provide disparate support for vector and raster operations
  • overlay and spreadsheet functions are base operations
  • spatial statistics, fuzzy logic, change detection, and decision support are not common

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References

1. Tobler, W. (1959). Automation and Cartography. Geographical Review, 49 (4), 526-534.
2. Tomlinson, R. F., H. W. Calkins, D. F. Marble (1976). Computer handling of geographical data. The Unesco Press: Paris. 214.
3. Guptill, Stephen C. (1988). A process for evaluating Geographic Information Systems. U.S. Geological Survey Open-File Report 88-105.
4. Clarke, K.C. (2003). Getting Started with Geographic Information Systems. Prentice Hall: Upper Saddle River. 340. See Chapter 8, "How to Pick a GIS"
5. Couclelis, H. (1992). People Manipulate Objects (but Cultivate Fields)- Beyond the Raster-Vector debate in GIS. Lecture Notes in Computer Science, 639, 65-77.
6. Goodchild, M.F. (1992). Geographic Data Modeling. Computers and Geosciences, 18(4), 401-408.

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Addenda

The Idrisi Kilimanjaro Tutorials

• "Using IDRISI" introduces the fundamental terminology and operations of the Idrisi system, including setting user preferences, display and map composition, and working with databases in Database Workshop. Exercises include:

  The IDRISI Environment
  Display: Layers and Collections
  Display : Layer Interaction Effects -- Blends, Transparency, Composites and Anaglyphs
  Display : Surfaces -- Fly Through and Illumination
  Display: Navigating Map Query
  Map Composition
  Palettes, Symbols, and Creating Text Layers
  Data Structures and Scaling
  Vector Collections and SQL
  Database Workshop : Creating Text Layers / Layer Visibility

• "Introductory GIS" provides an introduction to the most fundamental raster GIS analytical tools. Using case studies, the tutorials explore database query, distance and context operators, map algebra, and the use of cartographic models and IDRISI’s graphic modeling environment Macro Modeler to organize analyses. The final exercises in this section explore Multi-Criteria and Multi-Objective decision-making and the use of the Decision Wizard in IDRISI. Exercises include:

  Cartographic Modeling
  Database Query
  Distance and Context Operators
  Exploring the Power of Macro Modeler
  Cost Distances and Least Cost Pathways
  Map Algebra
  Multi-Criteria Evaluation-Criteria Development and the Boolean Approach
  Multi-Criteria Evaluation-Non-Boolean Standardization and Weighted Linear Combination
  Multi-Criteria Evaluation-Ordered Weighted Averaging
  Multi-Criteria Evaluation-Site Selection Using Boolean and Continuous Results
  Multi-Criteria Evaluation-Multiple Objectives

• "Advanced GIS" illustrates a range of the possibilities for advanced GIS analysis using IDRISI. These include
  regression modeling, predictive modeling using Markov Chain analysis, database uncertainty and decision risk, and Geostatistics. Exercises include:

Weight-of-Evidence Modeling with BELIEF
Database Uncertainty and Decision Risk
Multiple Regression and GIS
Dichotomous Variables and Logistic Regression
Geostatistics
Using Markov Cellular Automata for Land use Change Modeling

• "Introductory Image Processing" steps the user through the fundamental processes of satellite image classification, using both supervised and unsupervised techniques. Exercises include:

Image Exploration
Image Restoration and Transformation
Supervised Classification
Principal Components Analysis
Unsupervised Classification

• "Advanced Image Processing" includes issues of classification uncertainty and mixed-pixel classification. Idrisi provides a suite of tools for advanced image processing and this set of exercises highlights their use. The final exercise focuses on Vegetation Indices. Exercises include:

Bayes' Theorem and Maximum Likelihood Classification
Fuzzy Signature Development
Soft Classifiers I: BAYCLASS
Hardeners
Soft Classifiers II: BELCLASS
Dempster-Shafer and Classification Uncertainty
Sensing Vegetation in Arid Environments

• "Database Development" offers three exercises on database development issues. Resampling and projecting data are illustrated and some commonly available data layers are imported. Exercises include:

  Image Georegistration using RESAMPLE
  Digital Cartographic Databases
  Changing Reference Systems with PROJECT

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Concerning ArcGIS:

• ArcGIS is a collection of software products which includes three integrated applications: ArcCatalog, ArcMap, and ArcToolbox.
• ArcGIS comes in different flavors, including ArcView and ArcInfo.
• ArcView 8.x/9.x is different than ArcView 3.x:
  • Names have changed for things and functions.
  • Avenue scripts must be translated to work with ArcView 8.x/9.x.

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