GIS – INTRO LECTURE
Vicki Drake
Earth Sciences Department
Santa Monica College
Email: drake_vicki@smc.edu
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What is GIS?
A form of Information systems, applied to geographical data
A set of processes to produce information
A GIS, then, uses geographically referenced data, as well as non-spatial data
and includes operations that support spatial analysis
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a common purpose of the information is decision-making, for
managing use of land, resources, transportation, retailing, oceans or
any other spatially distributed and spatially referenced entities.
Why is GIS important?
GIS integrates spatial and other kinds of information within a single system –
offering a consistent framework for analyzing geographical data.
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GIS allows for manipulating and displaying geographical knowledge in new and
exciting ways by putting maps and other spatial information into digital form.
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GIS makes connections between activities based on geographic proximity e.g.,
linking toxic waste records with school locations through geographic proximity.
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GIS allows for access to administrative records, such as property ownership,
tax files, utility cables, and water/sewer pipes via their geographic positions
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Why is GIS so hot?
One reason: the high level of interest in new developments in computing
GIS adds a “high tech” to geographically-referenced information
Maps are, and have always been, of great fascination and computer mapping
is become more widespread
There is an increasing interest in geography and geographic education
GIS is an important tool in understanding and managing the environment.
GIS Market Value?
GIS is growing in significance to the business world.
The GIS markets is growing both in terms of number of GIS
operators/managers/techs as well as in market value – sales
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ESRI, developed of ARC/INFO, has shown significant increases in
revenue from ARC/INFO and subsequent software – including
ArcView, ArcExplorer, etc.
Contributing Disciplines and Technologies
GIS is a convergence of technological fields and traditional disciplines – such
as Geography, Geology, Biology,
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GIS is also an “enabling technology” because of the potential it offers for the
wide variety of disciplines which must deal with spatial data
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Each related field, provides some of the techniques that make up GIS – the
related fields emphasizing data collection – GIS brings them together – as
GIS emphasizes integration, modeling and analysis
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What’s Geography’s Role in this?
Geography has a long history of concern with understanding the world and
man’s place in it
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Geography also has a long tradition with spatial analysis
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© Vicki Drake
Santa Monica College
Fall 2001
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Geography provides techniques for conducting spatial analysis and a spatial
perspective on research
How does Cartography fit in?
Cartography is the display of spatial information
Currently, the main source of input data for GIS is maps.
Cartography provides a long tradition in the design of maps – which just so
happens to be the major and most important form of output from GIS
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Digital cartography, automated cartography – are all part of the computer
cartography age – and thus provides methods for digital representation and
manipulation of cartographic features and methods of visualization.
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Sources of Data for GIS?
Remote Sensing
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Images from space and the air are major sources of geographical
data
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remote sensing includes techniques for data acquisition and
processing anywhere on the globe at low cost, consistent update
potential
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Many image analysis systems contain sophisticated analytical
functions
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Interpreted data from a remote sensing system can be merged with
other data layers in a GIS
Photogrammetry
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Using aerial photographs and techniques for making accurate
measurements from them, photogrammetry is the source of most
data on topography (ground surface elevations) used for input to GIS
Surveying
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Provides high quality data on positions of land boundaries, buildings,
etc.
Geodesy
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Source of high accuracy positional control for GIS
Statistics
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Many models built using GIS are statistical in nature, many statistical
techniques are used for analysis
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Statistics are important in understanding issues of error and
uncertainty in GIS data.
Computer Sciences
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Computer-aided design (CAD) provides software, techniques for data
input, display and visualization, representation, particularly in 3
dimensions
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Advances in computer graphics provide hardware, software for
handling and displaying graphic objects, and techniques for
visualization
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Database Management Systems (DBMS) contribute methods for
representing data in digital form, procedures for system design and
handling large volumes of data, particularly access and update.
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Artificial Intelligence (AI) uses the compute to make choices based on
available data in a way that is seen to emulate human intelligence
and decision=making. Computer can act as an ‘expert’ in such
functions are designing maps, generalizing map features
Major Areas of Practical Application
Agriculture and Land Use Planning
© Vicki Drake
Santa Monica College
Fall 2001
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At the local level, GIS technology may have greatest impact on the way
agricultural land is monitored.
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Relatively simple GIS techniques can produce maps showing
coincidences of conditions important for planning and management –
including groundwater pollution, soil erosion, and changes in land
use.
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An important feature of adopting GIS at local level is to get
technology into the hands of decision-makers.
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© Vicki Drake
Santa Monica College
Fall 2001
Direct crop inventory and monitoring of growing conditions, annual
production, and prediction of national and international agricultural
market demand and supply.
Agriculture usually better monitored and inventoried than natural
resources, owing to national and economic importance.
Data Sources include: field reports, information on past production,
meteorological satellite data, and earth resources satellite data
(Landsat and SPOT).
First National scale Geographic Information System was the Canada
Geographic Information System (CGIS) operating continuously since
the late 1960s.
Project evolved to develop a national land capability classification to
compile an inventory of all potentially productive land in Canada.
1. Additional information was compiled to identify land use such as
forestry, recreation and wildlife.
2. Today, project has been modified and is one component of an
integrated group of computer-based GIS (Canada Land Data
Systems – CLDS) providing analysis services to national, provincial
and municipal agencies throughout Canada.
In the U.S., agriculture-related planning is usually done in the context
of more general land use planning activities –
Oklahoma State Univ and Okla./ Conversation Comm. used a GIS for
soil conservation planning – integrating analysis of soil type, slope,
farming practices and crop type to predict soil erosion
GIS technology from a PC-based GIS, was used to support planning
decisions for groundwater and surface water quality, irrigation and
municipal water supply in Kansas
Forestry and Wildlife Management
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Forestry encompasses not only the management of natural resources
within forested areas, but also includes grazing land for livestock,
recreation areas, wildlife habitat, and water supply sources.
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Decisions regarding accessing the compatibility of multiple-uses and
trading-off competing values are aided by the use of GIS technology.
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More and more, GIS technology has become mainstream in public
forestry agencies and private forestry companies alike – a result of
the benefit of producing current forest inventory maps with GIS.
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Standard forest inventory maps were done progressively – with only
a portion of the forests inventories each year – a process that could
take up to 20 years to complete!
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Meantime – changes in the inventory would be hand-drawn onto
existing map bases – by re-drafting the entire map would be too
time-consuming and expensive on a yearly basis.
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© Vicki Drake
Santa Monica College
Fall 2001
GIS forest cover maps can be updated on a continual basis and then
created as output as needed. Information can be updated in a matter
of weeks – not years!
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Data input sources would include: Remote sensing through large
scale aerial photographs with scales of 1:10,000 and 1:20,000
common) Field data, and photographs can provide data regarding
species composition: age, height. Density, etc.
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How does GIS differ then from Computer Cartographic programs?
GIS can be used to store and analyze the forest information in ways
that could not previously be done – such as calculating the
harvestable timber in an area – model the spread of forest fires – etc.
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Remote sensing and GIS, then, can provide cost-effective alternatives
to generate basic resource planning information.
Archaeology
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Another common directive for National Park and Forestry agencies is
the protection of archaeological sites.
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GIS technology is used to analyze known sites and predict location of
undiscovered sites.
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Using basic archaeological measurements – site size, location, age,
number of artifacts, number of dwellings, elevation, slope, aspect,
relief, etc – GIS can be used to develop predictive models for sites.
Geology
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Identification of useful geologic patterns in the landscape can be done
through relating diverse geologic data sets in a GIS.
Municipal Applications
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Georeferenced information – referenced to a specific geographic
location – about roads, schools, zoning, properties and parks is the
most common source of data for municipal GIS operations.
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These GIS applications provide systematic collection updating,
processing and distribution of land-related data
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Land Information Systems (LIS) and Land Records Information
System (LRIS) are frequently used to refer to specialized GIS
operations.
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One of the first uses of computers for municipalities: accounting –
payrolls, etc.
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1970s – engineering departments see value of computers for
drafting, surveying and map production and updates.
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Planning departments developed applications for statistical analysis,
mapping of land use, mapping of demographics (neighborhood,
county, city, etc.), projection of school, health and recreational
needs, etc.
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1980s – substantial investments made into GIS purchase by many
municipalities. To support functions including property management,
property appraisal, permit and licensing, planning, transportation and
routings, etc.
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