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GIS
Technology Brief
Geographic Information
System (GIS) is an organized collection of computerized
hardware, software, geographic data, and personnel to
efficiently capture, store, update, manipulate, analyze, and
display all forms of geographically referenced information. It
incorporates the essential elements of computer cartography
and relational databases into one system. The most important
characteristic of this system is that every mapped feature is
linked to a record in a tabular database and may be related to
records in other databases as well. In other words, the GIS
fully integrate geographic and tabular data.
This linkage between
maps and tabular data makes analysis of geographic data
possible. Computer cartography allows representation, but not
analysis of geographic data. Relational database managers do
not contain geographic information. Integrating the two
technologies in a GIS creates "intelligent maps" and the
ability to perform spatial analysis. Such analysis may include
spatial queries (such as "where is?") and spatial measurements
(such as "how far?"), or more complex problems such as best
routing, spatial correlation, districting, agricultural
analysis and predictions, etc.
GIS data are organized
in layers. Each layer contains only one kind of information
about the area in question. For instance, one layer might be a
soils map with the associated database containing information
about a large number of soil variables (Texture, PH,
Permeability, etc.). Another layer may be a map of roads
associated with a database containing road names, road class,
number of lanes, pavement materials, date last paved, etc. All
of the layers within a given project would represent the same
geographic area. These layers can be overlaid with one another
to allow the analysis of relationships between the different
layers.
This kind of analysis
is possible because the GIS is geographically referenced;
i.e., it is in a real-world coordinate system (Latitude,
Longitude, UTM, State Plane), allowing accurate overlay of
layers containing different data themes for the same
geographic area. For instance, a highway project corridor
could be overlaid with a soils map, even if they came from
sources at two different scales.
GIS
Functions
Several analytical
functions are supported by the integration of geographic and
tabular data. The most simple of these is database query. The
GIS automates searches for user-specified subsets of the
database. GIS is unique in that it allows searches in two
different ways. A query may be addressed directly to the
tabular data, and then displayed on the map (e.g. "select all
local councils with populations over one million and color
them yellow"). Alternatively, it may be addressed to the map,
with the results displayed in tabular form (e.g. "show me the
yam crop yield for the councils I have selected").
GIS also supports
spatial analysis, including automatic computation of lengths
and areas, recognition of adjacency, and finding spatial
correlations. Spatial analysis can answer questions such as:
How many acres of organic soil are within a given corridor?
What land uses are within 500 meters of the corridor? What
kinds of natural features are adjacent to prehistoric hunting
camps? On what kind of soil are you likely to find pineapple
growing? What environmental variables are most often
correlated with the presence of an archeological site?
The most sophisticated
kind of analysis that can be performed by the GIS is modeling.
Modeling has three properties:
First, it involves the
analysis of complex factors. For instance, modeling fire
behavior would involve analyzing forest type and density,
amount of dead fuel, slope, current soil moisture, wind speed
and direction, and a host of other independent variables.
Second, successful
modeling requires that the relationship between factors are
understood and clearly defined. The relationship may be
expressed with mathematical or Boolean operators. For example,
Darcy's law is a mathematical expression of the relationship
between the rate of water flow within an aquifer and the
permeability and slope of the aquifer.
Finally, modeling is
predictive. By understanding the relationships between a
complex factor and the dependent variable, one can predict the
value of the dependent variable in different places or
circumstances. Thus modeling answers such questions as: Where
is there a high probability of finding an archeological site?
How long will it take a contaminant from Well A to reach Well
B? What forest stands are most likely to burn in this fire
season?
GIS
Technical Courses from Agile!
1. Enterprise Data
Integration - Learn how to integrate and work with
geographical data from all over your organization.
2. Data Analysis
- See the big picture. Learn how to work with your data
geographically. See patterns you could not see before. Reveal
hidden trends and distributions. Gain new insight. Learn
techniques, which can give you the capability to work with
data in new ways and be creative and original.
3. Geographic Data
Management - Learn the technique of managing geographic
and spatial data.
4. Modeling
Techniques - Learn preventive and predictive modeling
techniques, which can be used to solve real-world problems.
Learn the technique of understanding relationships and forces
that drive your products, so you can make better decisions and
empower yourself to solve problems faster.
5. Spatial Analysis
- Learn the technique of analyzing your data in space and
time.
6. Display &
Presentation of Geographic Data - Learn how to present
your results and ideas. Learn how to make professional
publication-quality maps and create interactive displays by
linking charts, tables, drawings, photographs, etc. Learn how
to present geographical information to inform and motivate
others.
7. Map Creation &
Editing - Learn the technique of mapping new geographic
information and editing existing ones.
8. Developing
Map-Based Applications - Learn how to use built-in
object-oriented scripting language to develop custom tools,
interfaces and complete map-based applications. Develop the
capability to give others the power to work geographically
without the associated high GIS investment.
9. Geo-processing
Capability - Learn to utilize the inherent geo-processing
capabilities to quickly produce results.
Components of Agile GIS System
1. HP DesignJet 750c
w/ stand 240Volts (Manufacturer Part # C4709#ABA).
2. Calcomp Digitizer,
Drawingboard 18x24 Corded Cursor/16BTN/.002 Accuracy Opaque
(Manufacturer Part # 342402121111)
3. Erdas Mapsheets
1.2a Fullboxed version.
4. PC Arc/Info Version
4.0 for Windows.
5. ArcView Version
3.2a for Windows.
6. Adobe Photoshop
Version 5 for Windows.
7. Accessories -
Printer Cartridges BCYM, Printing Paper, Photo Paper, etc. |
