The Nature of Geographic Information Systems
By Charles Convis, ESRI, Sept 28, 1996
Table of Contents Section 3
What is GIS?
Top 10 Reasons Biologists Don’t Use GIS
GIS and Antique Cars
Cassini’s Planisphere, a Framework for the World
What is GIS Again?
PARTS OF A GIS
Data Foundations of GIS
Technology Foundations of GIS
Theoretical Foundations of GIS
Human Foundations of GIS
HOW GIS INTEGRATES:
GIS Integrates Data
GIS Integrates Technology
GIS Integrates Theories and Methods
GIS Integrates Different Human Needs
GIS and a New Framework for Conservation Biology
GIS Integrates Data in a Common Data Model
The fact that a wide variety of data contains defined relationships
to space means that a location in space can be used as a meeting ground
for all of that data, regardless of its forms, content and assumptions.
This is one of the most powerful concepts in GIS. Science and society are
characterized by deep divisions between different disciplines, such as
the social and physical sciences, and the data collected by these different
disciplines reflects these divisions. There is no simple way to imagine
combining demographic data collected about families with a soil health
classification based on patterns of soil microflora populations, yet if
those families were farmers it would be very important. Since both of these
can be represented in space, families as street addresses and soil types
as a classified landscape, they can be combined with a GIS to study issues
such as the effect of poor soil biodiversity on family farm income.
An important concept in spatial integration is the spatial standard.
GIS provides tools to make 2 different spatial data sources match each
other, but without reference to a common basemap standard it is difficult
to go any further. A spatial basemap provides a common framework that any
data source can be registered to, and once registered, all other data meeting
that same standard are immediately available for comparison with the new
data. A basemap also commonly includes control points, precisely-located
benchmark coordinates which allow the error and accuracy of positional
data to be readily determined. The importance of controls in any scientific
effort does not need to be reiterated.
Another important concept is scale. Basemaps of different scales represent
completely different things in the landscape, mainly because each uses
a different minimum mapping unit, representing the smallest landscape feature
which can be captured and described in the database. Note that this concept
of resolution applies equally to mapped locations and to feature descriptions
and classifications. Most GIS projects will need to use several different
scales, depending on the patterns and processes under study, and may therefore
need to select several different basemap standards, and according, several
different classification schemes. In the same way that basemaps can be
nested in common sets of control points, classification schemes can be
hierarchical, with finer divisions based on higher level categories.
GIS Integrates Technology
One of the trends in computer development, especially recently, has
been a move away from specific programming languages towards integrated
software development environments offering a single platform with a selection
of languages, interfaces and support tools. This works by basing the languages
on a common architecture so that they can function compatibly with one
another. From the very beginning, the goal of software development at ESRI
was to produce tools that would function in whatever hardware and software
environment a user wanted to utilize, unlike other GIS efforts based on
single platform and proprietary designs. As a result, software development
at ESRI has focussed upon building a well-engineered architecture for doing
GIS functions within diverse and rapidly-changing technologies, and ESRI
was a pioneer in the computer industry in offering a single software environment
that functioned identically across multiple UNIX, PC and Mac platforms
and integrated with every mainline database management system. This architecture
has matured over 2 decades and now regularly incorporates new advances,
such as ActiveX and dynamic web servers.
The figure shows some of the classes of operations commonly carried
out in a GIS effort and illustrates the myriad functional relationships
and interconnections between the different ESRI software modules and applications
used to carry them out.
GIS Integrates Theories and Methods
Because it is based on a common spatial data model and integrated many
software tools within a single architecture, GIS permits the concurrent
application of different theories on the structure of space and nature.
This can be as simple as overlaying a demographic map with it’s implicit
assumptions of the role of human motives in directing urbanization with
a soil map and it’s implicit assumption of the role of soil fertility in
determine land use. Failure to account for differences in implicit assumptions
is a constant problem in data integration and data sharing.
Beyond this, GIS as an integrative framework makes it ideally suited
for the study of ecology and geography, which themselves represent the
union of numerous disciplines in trying to understand pattern and process
in nature and in humans. The ability to explicitly manage spatial standards
and basemaps provides important frameworks for the development of spatial
models.
ESRI’s software also solved an old problem in geography and ecology,
namely the differences between continuous patterns on the landscape and
discontinuous ones. Continuous patterns like vegetation were best represented
by continuous grid of cells, while discontinuous patterns like land tenure
and point data were best represented by points, lines and polygons. When
the GRID cell-modeling software was integrated into the polygon data model
under ArcInfo several years ago, this problem finally became manageable.
GIS integrates different spatial and attribute models using different methods
for different kinds of theoretical analyses so as to create meaning and
better decisions.
GIS Integrates Different Human Needs
GIS is a central part of a number of planning and structured decision-making
efforts, allowing the explicit management and recognition of different
views of the landscape into a single managed process of consensus. It is
also the most widely used computer technology among planning and land management
agencies worldwide. It’s utility in conservation, however, is limited by
political and social factors. The best available science must always be
included in planning and land decisions, but decisions still usually go
where the power is, and conservation can’t succeed unless there is the
mandate and the political will to back up what the science proves. So an
important precondition for integrating different players is to make sure
they are all on the same field at the same level. Unfortunately, this fact
of life is left out of most theories of computer supported collaboration
and decision support.
Once there is some parity in political will, the integration of rigorous
scientific data from different parties into a common framework can be extremely
productive at illuminating precisely the areas of conflict, clarifying
the effect of each individual contribution upon the whole, and suggesting
the specific paths to resolution.
Cassini’s Planisphere:
Solving Problems for Myself and Others
Before we finish, let’s take another look at Cassini’s Planisphere and
what it represented as a framework for organizing information in response
to human needs, compared to numerous similar efforts in biological data
today. Cassini was trying to support Louis XIV’s desire to use the sciences
in order to advance the French Empire worldwide. They needed one central
location, accessible to the king where they could begin to form a view
of what the world really looked like in order to better guide and advise
French navigators. They weren’t especially interested in helping other
countries navigate better. Nowadays we see this approach especially common
in scientific databases, with center after center being built for the purpose
of collecting and managing centralized scientific databases. What people
are doing in these programs is solving problems for themselves or their
institutions the way Cassini solved problems for France. This can be contrasted
with another approach to technology and data, the service-oriented approach
of solving problems for others. As you can see, an entirely different set
of assumptions are needed in this case. Neither approach is "right"
and in fact both are needed, but the problems occur when groups that succeeded
in solving problems for themselves decide to shift to a services approach
without a fundamental change in assumptions. That’s why we see programs
offering high-end Unix stations as the "solution" for specimen
data management. That’s why we see programs who purport to be making their
data available to anyone who needs it but who don’t even have a data publishing
program! It takes two distinctly different frames of mind to be successful
in these two directions, and it is rare to find an organization that can
successfully combine both.
Now let’s summarize by looking again at all these different things GIS
is, all these different integrative frameworks. Do they have anything to
offer biodiversity? Can they be combined into a single concept for the
goal of biodiversity conservation?
GIS and a New Framework for Conservation Biology
This is a conceptual diagram of one possible way to arrange the capacities
and activities in GIS with those of biodiversity institutions to promote
the development and integration of better data and better tools for biology.
It derives in part from already-functioning programs in technology transfer
and already-established database efforts. The details of governance and
administration are sketchy since as a GIS person I’m not as directly involved
in those areas as you are, and I would hope that if such an idea finds
merit, these details can be filled in by others. It may be that you already
have plenty of such proposals and instead stumble on other problems I’m
not aware of, but at least you can see here how we think the technology
of GIS can have a contribution and perhaps you have in mind other productive
ways to apply these ideas and our offer of help.
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