A Collaborative GIS Decision Support Model on Internet
Lockheed-Martin Service Group
Visualization Center of National Environmental Supercomputing Center
U.S. Environmental Protection Agency
Jeff Wang, Ph.D. is a technical leader in the Visualization Group of National
Environmental Supercomputing Center of USEPA. Dr. Wang is an advocate for the
use of Internet technologies in the environmental decision support community.
He organized the first-time-ever MBONE broadcast of an EPA workshop to the
Internet community and developed several World Wide Web (WWW) information
service sites to promote decision support in different industries. Dr. Wang
also have extensive experience in GIS applications. His research interest is
collaborative GIS model on the Internet.
The international Geographical Information System (GIS) community has
experienced enormous growth in the past decade because of the advancement of
computer, remote sensing, and space technologies. The typical size of a GIS
dataset has grown in magnitude from megabytes a decade ago to gigabytes now.
The typical use of GIS has evolved from simple cartography to multimedia
decision making support in the same period. Typical users have expanded from
the geographical survey community to virtually all communities. It is no
longer possible to put all GIS data into a centralized location and use one
computer to handle the data processing, let alone intensive data analysis for
decision support. However, the society demands more GIS data and better
utilization of these data.
The most promising solution to the GIS growth problem is the Internet. The
Internet, which is defined as interconnection of computers around the world,
has grown from tens of computer hosts two decades ago to tens of millions of
computer hosts today. It is one of the fastest spreading
technology/communication tools in the United States and around the world.
Meanwhile, the Internet community has been agonizing over how to develop
applicable programs to use the full capacity of Internet in the future.
Collaborative Spatial Decision Making (CSDM), or Collaborative GIS, will
advance to be one of the most popular applications on the Internet. Future GIS
data can be managed and served in a distributed system at the
county/metropolitan or township level. In such a system, the data can be
updated constantly by the people who are most familiar with the environment. A
huge computer network will connect all of these computers. A user of the GIS
data will run a client anywhere and be able to discover and filter the GIS
data, retrieve wanted data, conduct analyses, and archive results. The
analytical results are then used for decision making. An intelligent agent will
be used for optimizing the solutions and audio-visual tools will be used to
conduct conferences and utilize human expertise.
Fortunately, the GIS community does not have to reinvent the wheel in order to
build collaborative GIS. The Internet community has developed many of the
needed technologies to accommodate the future growth of collaborative GIS.
These include research and development of the WWW, gophers, the Wide Area
Information Service (WAIS), Computer-Supported Collaborative Work (CSCW)
environment, object-oriented programming (OOP), client/server paradigm, and
This paper will propose a CSDM model and discuss the related major issues.
2. Important Issues in a CSDM
In this section, we will discuss some of the important issues in development of
a CSDM model. We will only provide some brief discussions on each issue and
will provide in-depth discussion of each issues in separate studies.
2.1 GIS Data Model
Most of the current GIS data models are based on relational database technology
in a centralized location. This can no longer continue because the "modern"
(compared to 10 years ago) GIS applications demand more efficient use of memory
and a shorter application life cycle. Therefore, the future data model will be
object-oriented and reusable. Furthermore, the GIS data model will take "open
system design" approach, so the data model is interoperable, reconfigurable,
and can be grouped with other data models to form a more powerful meta-model.
One of the current practices in telecommunication applications, which will be
continued through the next few decades, is bandwidth on demand. Users can
choose their bandwidth configurations based on cost. Therefore, GIS
applications will face different users groups in different geographical
locations with different bandwidth capacity. One of the solutions to this
problem is to implement sharable objects in the data model, so we can build a
collaborative GIS data model.
2.2 Distributed vs. Centralized
Although many GIS applications are still using a centralized approach for data
storage and management, few will dispute that we are unable to continue using a
centralized approach. The most popular technology paradigm nowadays is the
enterprise client/server environment, in which the more powerful data
processing machines are used as data servers, and the less powerful desktop PCs
are used as clients. Obviously, the old, centralized GIS applications will be
obsolete, and the new, client/server GIS environment will be established.
2.3 GIS Information Archive, Retrieval, Discover, and Management on
In a client/server computing environment with reasonable bandwidth, we can do
much more on GIS information archive, retrieval, discover, and management. For
example, WWW (also called "the Web") uses universal resource locators (URLs),
hypertext transmission protocol (HTTP), and search engines to facilitate
information archive, retrieval, discover, and management. The efficient use of
computers and bandwidth contributes a great deal to the popularity of the Web;
and of course the user-friendly graphical user interface (GUI) contributes a
Without a major development effort, we should be able to achieve satisfactory
results by using the existing software environment. In fact, a prototype of
the GIS information discovery and management model can be implemented using WWW
and its associated software programs. In WWW, a data server is a Web server
that serves text, HTML documents, and images; a client is a Web browser such as
NCSA Mosaic or NetScape. We can run a mail robot around the Web to pull out
information we want at any time. If we implement URLs in a certain format on
all the GIS data servers, the mail robot program can identify these special
URLs and discover what we want in a reasonable time frame. And we can archive
our data by File Transfer Protocol (ftp) into the data server. These can all
be done by clicking on the homepage.
Later in this paper, we will propose a CSDM model with 3-tier client/server
environment. This model will make use of the WWW as well as the local
client/server environment on the Local Area Network (LAN) or Metropolitan Area
2.4 Audio-visual Conference and Other Means of Communications
The necessity of having an audio-visual conference capability depends on the
intended application. In some applications, such as Intelligent Vehicle
Highway System (IVHS) and emergency road service, a conference system is
necessary because the scene is too chaotic to be described clearly by other
means. But in most of the cases, especially those involving scientific
research and analysis, audio conference with very low bandwidth video
conference should be sufficient.
Use of the Differential Global Position System (DGPS) will be very helpful in
gathering and updating the GIS data, as well as the utilization of GIS data to
Even the traditional mail delivery can make a difference: if we take the
sharable object approach, the users can order the data, presumably on a CD-ROM,
by mail. When the decision makers call on a conference, each party can insert
the CD-ROM, and only use the network to pass control commands, so all parties
can share applications and conserve the use of bandwidth.
2.5 Visual Interface and GUI
A consistent GUI and visual interface across all platforms is one of the
secrets of success in this client/server environment. In fact, the success of
NCSA Mosaic is not purely luck. It is the only program that can run on
IBM-compatible PCs, Macintosh computers, and UNIX Workstations while retaining
a remarkably consistent interface. And it is free of charge!
In a 3-tier client/server environment, the Web server on the Internet can be
hidden from the user clients, so we can still give the users the impression of
a consistent GUI. The GUI should also hide the underlying file management
process from the users, and yet give the users freedom to troubleshoot the
2.6 Intelligent Agent
Anyone who has ever run a search engine or mail robot program on the Web has
been overwhelmed by the huge amount of information available for his/her search
subject. But all these information may or may not be related to the subject,
depending on how people find them. For the GIS datasets, things can be more
complicated because of the size of the data, and it may take much longer to
search for a piece of data. Therefore, an intelligent search engine is needed
to filter out some unwanted information before they reach the users. This
intelligent search engine is called "intelligent agent," or "information
The building of the intelligent agent is a combination of computer network,
universal resource location, data organization and indexing, and artificial
intelligent. The GIS community should take the lead in applying these advanced
technologies to solve the distributed GIS problem.
2.7 Automation of Decision Support Process
Automation of the decision support processes is crucial to the success of CSDM.
A decision making process usually involves a tremendous amount of data
analysis and "what-if" simulations. Actually, the major problem is not the
analysis, but the file management. A decision support system should hide all
of these low level works from the users, but at the same time still give users
the flexibility to change parameters, conduct quality assurance of the process,
and extract comprehensive information through the decision making process.
Furthermore, an optimization program should be available to the decision makers
so they can run "what-if" scenarios in batch mode and obtain the "best-guess"
solutions. This is itself a big topic in the decision support theory, and it
is beyond the CSDM research domain. Yet CSDM should utilize this knowledge for
its own benefit.
2.8 Joint Application with Other Discipline
Even a very powerful CSDM cannot solve all of the current problems. If CSDM
works with other decision support systems in other disciplines, the system can
be very successful. Therefore, CSDM should be open, object-oriented, reusable,
and able to accommodate major data format in the market (e.g., HDF, NETCDF,
A good example of CSDM cross-discipline application is the ecosystem management
system in the environmental field. On one hand, an ecosystem management system
demands a lot of GIS data, on the other hand, the ecosystem management system
needs to use environmental modeling and simulation to support the decision
making. Hence, by using the existing environmental decision support systems
and the CSDM, one can easily extend the decision making to the earth's
ecosystem. However, at this point, the two communities have been unable to
build something together that is truly integrated and interoperable.
3. A CSDM Model
3.1 Data Model
The data model of this CSDM system will be object-oriented and closely
disseminate real world geographical objects.
3.2 System Architecture
The system will be open, modular, and object-oriented. It will be expandable
so it can work with other decision support systems to form a meta decision
support system for large scale, complex problems.
3.3 Distributed Desktop Environment
The system will use 3-tier client/server structure. The first layer is the
client layer, the local clients will be connected with a local GIS server,
which usually be the file server on a LAN. The collection of these GIS servers
is the second layer. The third layer is the Internet layer, which connects all
the GIS servers together. The command and control centers of the GIS server
network are strategically placed in different locations all over the country
(or world). These centers are called "GIS meta-centers."
Under this distributed environment, the clients can be run by a wide range of
UNIX workstations, IBM PCs, and Macintosh computers. The local GIS servers can
be run on typical server machines, which have more memory and storage capacity.
In the meta-center, supercomputers and high density storage are used to handle
the management tasks.
3.4 Collaborative Environment
For co-authoring, document sharing, and collaborative work, the model will use
the shared object approach. The users may obtain/purchase a copy of GIS data
via CD-ROM or via Internet applications like ftp and WWW before the
collaboration, then load the software and data to their computers when the
conference begins. This approach is a collaborative process in asynchronous
For the video and audio conferencing, the model will use the Internet (e.g.
MBONE) or ISDN to conduct video-audio conference. So in the collaboratory
process, users can start the video-audio conference, run the CSDM model, and
apply remote control to manipulate the shared objects. This approach is a
collaborative process in distributed synchronous mode.
3.5 GUI and Visual Interface
X/Motif-like GUI is the de facto standard in current GUI development industry,
therefore, the model will use X/Motif to construct the GUI and Visual Interface
of the GIS model.
3.6 Information Archive, Retrieval, Discovery, and filtering
The model will use the newly-built or existing Internet tools to archive,
retrieve, and discover GIS information on the Internet.
4. Concluding Remarks
In this paper, we presented a CSDM model and discussed issues we are facing
currently. We proposed a comprehensive CSDM model that will work on the
Internet and will provide different levels of opportunity of participation. We
used the Internet client/server environmental as our backbone and decision
support as our goal, and we conclude that this model, if realized, will benefit
the GIS and environmental science community at large.
Today, Internet technology is utilized at an ever increasing rate. USEPA has
already used satellite TV and MBONE to transfer environmental technology to the
user community. Further, more and more divisions inside EPA and other
government agencies are providing their staffs with WWW access and establishing
their own WWW home pages in order to provide increased access to public
information as well as convey information to the public and other government
institutions. At the same time, the GIS community has been spearheading the
utilization of Internet to make GIS data available to the general public. It
is inevitable that CSDM model will use Internet as a major testbed for
In the future, the U.S.EPA Scientific Visualization Center (SVC) pursue the
support of scientific visualization of ecosystem management and combine GIS
into environmental scientific visualization. SVC's goals are to support the
decision making processes used by environmental decision makers, and to convey
the scientific research results more effectively to the general public. We
will be actively supporting and participating in the development and deployment
of the CSDM models.
Jeff Wang, Ph.D., System Manager/HPCC, U.S. EPA Scientific Visualization Center
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