Towards a Sustainable
GIS:
A Case for Open-Source GIS.
Marie Negron
Geography 26
Spatial Data Acquisition for GIS
Professor P.Veisze
Spring
2002
ABSTRACT
With the advent of new technologies,
planetary exploration is an adventure in which we can all take part. One of the
technologies by which we are enabled to do this is a Geographic Information
System, or GIS. Originally an instrument for terrestrial spatial analysis, it
is being applied to planetary exploration. A GIS is capable of analyzing spatial
data and producing visual displays of that data. While the public has had many
opportunities to view breath-taking images of the planets that make up our
solar system, these images have been static. Now, thanks to the United States
Geological Survey, planetary data is available to the public for analysis. With
PIGWAD, or the USGS Planetary Interactive GIS-on-the Web Analyzable Database, access
to this tremendous database is available on the World Wide Web. Bringing this
wondrous tool to the public has not been easy, however. This paper is a
reflection on the difficulties which arose while creating PIGWAD, and what can
be learned from following its development.
Introduction
The
USGS Planetary Interactive GIS-on-the-Web
Analyzable Database, PIGWAD, is a Web-based, user friendly GIS interface
which provides scientists and layman alike access to the tremendous database
compiled during the many planetary exploratory missions. The Geographic Information System, or GIS,
technologies give one the tools to not only view different types of data
together, but also to perform various analyses. Bringing this dynamic GIS on
the web to full
functionality has not been without its problems,
however, and by following the development of the site, much can be learned
about bringing a GIS to the web.
This paper, with PIGWAD as its guide, will
investigate the motivation behind implementing a web based GIS, describe some
of the difficulties encountered in doing so, and reflect upon the resultant
solutions. Will these solutions lead to a method by which PIGWAD might become
sustainable? Or is PIGWAD likely to fall
prey to obsolescence?
Background
A Geographic Information System (GIS) is an organized
combination of computer hardware and software, which efficiently collects,
stores, updates, manipulates, analyzes, and displays a geographic database in
tabular, graphic, or map form (DeMers, 2000). A GIS (1) brings flexibility in
managing data, (2) is a cost and time efficient method of producing large
databases, (3) has the ability to create multilayered databases for comparison
studies, and (4) has the capacity to readily update and add information
obtained from future studies (Hare, et al, 1999).
As scientists became exposed to its functionality, application
of GIS in the planetary sciences grew dramatically (Hare et al, 1999). The cost
of creating of a stand-alone GIS, however, can be an expensive and a daunting
task beyond the scope of most planetary projects.
Thus, NASA’s
Planetary Geologic and Geophysics Program, under the auspices of the Planetary
Cartography and Geologic Mapping Work Group chose to support a planetary, web
based GIS that the entire science community may utilize. In May of 1999, the
Planetary Interactive GIS-on-the-Web Analyzable Database (PIGWAD) became operational
(Hare, et al, 1999).
A proprietary GIS software program and its web server
application permitted the generation of a website with predetermined datasets
which could then be viewed, queried, exported, and annotated in any combination
of datasets (Hare, et al, 1999). PIGWAD steadily grew in functionality and
analytical power as more diverse databases were created (Hare, et al, 2001).
The original intent behind the creation of PIGWAD was
to bring planetary data to as wide an audience as possible. Yet, as noted
above, costs of establishing a stand-alone GIS can be prohibitive.
Additionally, the remote sensing apparatus have collected hundreds of millions
of data points, and continue to give gigabytes of Martian data alone (Hare, et
al, 2002). This is enough data to stress even the most modern stand-alone (or
LAN) systems. It becomes apparent that the tripartite goal of accessibility, high
GIS functionality, and efficiency in handling the data is not achieved without
some difficulty. Consequently, PIGWAD started to experience “growing pains”
(Hare, et al, 2002). It is to these “growing pains” that we now turn our
attention.
Positing
Obsolescence
The evolution of PIGWAD is well documented. Its
inception and fine tunings have been laid out in detail in several articles. We
are given a glimpse into the process of creating and maintaining a web GIS.
In creating a
GIS, hardware, software, and technical expertise add up to an expense most
planetary projects are unable to justify (Hare, et al, 1999). Thus, PIGWAD, via
the World Wide Web, would step up to provide access to the tools of a GIS as
well as provide access to the planetary database… And all would be well. Initially,
all was well. Then PIGWAD started to experience difficulty in interoperability
across computer platforms. Supporting multiple browsers, versions, and operating
systems became its biggest hurdle (Hare, et al, 2002); access to PIGWAD was
limited.
Was PIGWAD experiencing a fleeting case of obsolescence?
How would interoperability be
established? Would the solution make for a sustainable planetary GIS?
It is difficult to think of a system which is barely
three years old as obsolescent. The term implies agedness. However, when
speaking in terms of even the simplest digital objects, their use requires the successful interaction of a
complex system of hardware and software. In PIGWAD’s case, the interaction amongst complex computer systems must meet with success in order
for it to maintain its utility. It is in these terms that obsolescence is used
here. It is its inaccessibility to all computer platforms which abridged the
utility of PIGWAD. Thus, it might be posited that PIGWAD faced a tentative
obsolescence.
Open Source as a Solution
How then, does PIGWAD become more compatible with
different browsers and machine types? Upgrading its map server to a new version
established some compatibility, yet its proprietary software and map server
capabilities were still in need of support. This issue led to the investigation
of Open-Source GIS protocols as an option (Hare, et al, 2002).
The OpenGIS Consortium (OGC) was built to help
establish and promote a series of protocols for sharing GIS resources as
established by the Open-Source Consortium (OSC). The Open Source Initiative
specifies open access to the source code of a software program, and identifies
the distribution terms with which open source software must comply. OpenGIS is
dedicated to an interoperability specification which supports a wide range of
applications, datastores and services. Bringing us to the question: Did
utilizing open source standards resolve the interoperability issues that PIGWAD
faced?
Adoption of OpenGIS code did help make streaming of planetary
GIS datasets compatible on any platform (Hare, et al, 2002). Meaning that OpenGIS
accomplished what it was designed to do. Communication between PIGWAD and other
proprietary and open source platforms was, indeed, established. T.M. Hare of
the USGS admits, however, that as advances in software become available, and
new tools for internet mapping are developed, OpenGIS technologies will be
harder to support (Hare, et al, 2002). In other words, the most up to date
software and gadgetry is a temptation that is hard to resist. Perhaps it is
even harder to resist when more powerful analytical functions are needed to
keep up with the data.
Sustainability
in Light of Temptation
As we have seen, a Geographic Information System is a
costly matter. The cost of the software alone is an obstacle to access. While
following the ins and outs of PIGWAD’s development provided insight into creating
a planetary GIS, it is hardly a typical case.
With the magnitude of its data processing needs, and
the complexity of its system, PIGWAD is more likely to encounter a higher
degree of malfunctions (DeMers, 2000) necessitating intervention on some level.
The average users of a GIS do not have a need to push the program beyond its
limits (DeMers, 2000).
Might PIGWAD
reach a point of sustainability? It does seem far from certain, for a
sustainable GIS is one which can be managed in the most resource-efficient
manner. PIGWAD will require fine-tuning, and will invariably incur expense; leading
to the conclusion that perhaps PIGWAD is not a fitting candidate as a model of
sustainability.
With regard to open source programs, however, their
utilization would fit neatly into a model for a sustainable GIS since they are
free of cost. Moreover, an open source GIS might be capable of meeting the
present needs of the average user, and remain somewhat flexible into the future
as the program becomes fine-tuned. Those utilizing an open source program
invest in its continued development by adding codes which update its
functionality. Cost and risk of obsolescence is reduced.
Conclusion
The USGS planetary GIS proved to be an unlikely candidate
as a model for a sustainable GIS. Many of the desired analytical enhancements
available through proprietary means do not support an open source format (Hare,
et al, 2002), necessitating continued expenditures of resources in order to
maintain accessibility. This seems to place PIGWAD in the precarious position
of dependence upon continual upgrades in order to remain highly functional.
Its very
framework of a web based GIS, however, does open access to a part of the
planetary database which would have been unavailable otherwise. The creators of
PIGWAD have equipped the site with many tools for analysis and visualization of
the data. It can certainly be said that their efforts have not been wasted.
While open source programs fit neatly within a sustainable
GIS framework, it seems that developments in distributed computing over the
World Wide Web are likely to make it the modus operandi of the future. In which
case, sustainability would be the norm, for web interoperability would allow
for future geoprocessing applications to be gathered from open, multi-network-delivered
geo-computing and location services.
References
Cowen, R. “Unveiling
Mars’ Watery Secrets”, Science News,
DeMers, Michael N.,
2000. Fundamentals
of Geographic Information Systems.
Hare, T.M., Dohm, J.M.,
Tanaka, K.L. “GIS and its
application to Planetary Research” 2000, Lunar and Planetary Science
Conference Abstracts. XXX11 #1889
Hare, T.M., Tanaka, K.L. “Using MOLA and MOC in a GIS”, 2000 Lunar
and Planetary Science Conference Abstracts. XXXI, #1907
Hare, T.M., Tanaka, K.L. “PIGWAD-Successfully
evolving with a few growing pains” 2001 Lunar and Planetary Science
Conference Abstracts. XXXII
Hare, T.M., Tanaka, K.L. “ PIGWAD-OpenGIS and Image Technologies for Planetary Data Analysis” 2002 Lunar and Planetary
Science Abstracts XXXIII, #1365
Hare,
T.M., Tanaka, K.L. “Planetary Geographic
Information Systems (GIS) on the Web”.Lunar
Planetary Conference, 1999,
Masser,
Raeburn, Paul. 1998.
Uncovering the Secrets of the Red Planet: Mars,
The National Geographic Society:
Walter, Malcolm. 1999. The
Search for Life on Mars, Perseus Books:
Websites
Open
Source information and applications
http://grass.itc.it/index2.html
http://csdms.org/gramchitra
http:// freegis.org
http://opengis.org/
http://opengis.org/ogcFaqs.htm#q5
PIGWAD and sites dealing with Martian data
http://webgis.wr.usgs.gov/
http://mars.jpl.nasa.gov/mgs
http://marsoweb.nas.nasa.gov/landingsites/