196 lines
4.2 KiB
HTML
196 lines
4.2 KiB
HTML
<HTML
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>What is a GIS?</TITLE
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>The Geographic Information Systems: GRASS HOWTO</TH
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><A
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NAME="WHATISGIS"
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>1. What is a GIS?</A
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></H1
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><P
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> There are many ways to describe a Geographic Information System. Here
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are three working definitions (from David A. Hastings, 1992, Geographic
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Information Systems: A Tool for Geoscience Analysis and Interpretation):
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</P
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><OL
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TYPE="1"
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><LI
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><P
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> (The minimal definition): A GIS is a hardware/software system
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for the storage, management, and (with hardcopy or screen
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graphic) selective retrieval capabilities of georeferenced data.
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Definitions like this one are often used by vendors and users of
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vector-only GIS, whose objective is sophisticated management and
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output of cartographic data.
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</P
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></LI
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><LI
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><P
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> (A parallel definition): A GIS is a hardware/software system for
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managing and displaying spatial data. It is similar to a
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traditional Data Base Management System, where we now think in
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<I
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CLASS="EMPHASIS"
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>spatial</I
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> rather than in tabular terms, and where the
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"report writer" now allows output of maps as well as of tables
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and numbers. Thus we can consider a GIS a "spatial DBMS" as
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opposed to traditional "tabular DBMSs." Few people use this
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definition, but it might help to explain GIS to a DBMS user.
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</P
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></LI
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><LI
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><P
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> (A more aggressive definition): A GIS is a system of hardware,
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software, and data that facilitates the development,
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enhancement, modeling, and display of multivariate (e.g.
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multilayered) spatially referenced data. It performs some
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analytical functions itself, and by its analysis, selective
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retrieval and display capabilities, helps the user to further
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analyze and interpret the data. Properly configured, the GIS
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can model (e.g. synthetically recreate) a feature or phenomenon
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as a function of other features or phenomena which may be
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related - where all features or phenomena are represented
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(characterized) by spatial and related tabular data. The
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analytical objectives described here are sometimes controversial
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- and often given lip service by cartographic GIS specialists
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who have not yet seen what can be accomplished scientifically by
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a select few GISs that go beyond cartographic approaches.
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</P
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></LI
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><LI
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><P
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> Another definition can be found at
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<A
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HREF="http://www.geo.ed.ac.uk/home/research/whatisgis.html"
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TARGET="_top"
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><I
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CLASS="CITETITLE"
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>the University of Edinburgh.</I
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></A
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>
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</P
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>The Geographic Information Systems: GRASS HOWTO</TD
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>What Is GRASS?</TD
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