1. Introduction to GIS systemsIntroduction to GIS systems
By: Vivek SrivastavaBy: Vivek Srivastava
viveksrivastava09@gmail.comviveksrivastava09@gmail.com
2. 1.2
ObjectiveObjective
To understand
The Geographic Systems that help in organizing
spatial and attribute data.
The context of GIS usage- the discipline that
deals with all aspects of spatial data handling
called Geoinformatics.
4. 1.4
GIS – What is it ?GIS – What is it ?
Geographic/Geospatial Information
information about places on the earth’s surface
knowledge about “what is where when”
Geographic/geospatial: synonymous
GIS--what’s in the S?
Systems: the technology
Science: the concepts and theory
Studies: the societal context
5. 1.5
GI TechnologiesGI Technologies
Global Positioning Systems (GPS)
a system of earth-orbiting satellites which can provide precise (100
meter to sub-cm.) location on the earth’s surface (in lat/long
coordinates or equiv.)
Remote Sensing (RS)
use of satellites or aircraft to capture information about the earth’s
surface
Digital ortho images a key product (map accurate digital photos)
Geographic Information Systems (GISy)
Software systems with capability for input, storage,
manipulation/analysis and output/display of geographic (spatial)
information
GPS and RS are sources of input data for a GISystems.
A GISystems provides for storing and manipulating GPS and RS data.
6. 1.6
Defining GISDefining GIS
• The common ground between information processing and the
many fields using spatial analysis techniques. (Tomlinson,
1972)
• A powerful set of tools for collecting, storing, retrieving,
transforming, and displaying spatial data from the real world.
(Burroughs, 1986)
• A computerized database management system for the capture,
storage, retrieval, analysis and display of spatial (locationally
defined) data. (NCGIA, 1987)
• A decision support system involving the integration of spatially
referenced data in a problem solving environment. (Cowen,
1988)
• A spatial information handling tool.(Goodchild, 2002)
7. 1.7
GISystemGISystem
A system of integrated computer-based tools for end-to-end
processing (capture, storage, retrieval, analysis, display) of data
using location on the earth’s surface for interrelation in
support of operations management, decision making, and
science.
A map with a database behind it.
A virtual representation of the real world and its infrastructure.
queried to support on-going operations
summarized to support strategic decision making and policy formulation
analyzed to support scientific inquiry
8. 1.8
Why Study GIS?Why Study GIS?
80% of local government activities estimated to be geographically based
plats, zoning, public works (streets, water supply, sewers), garbage collection, land
ownership and valuation, public safety (fire and police)
a significant portion of state government has a geographical component
natural resource management
highways and transportation
businesses use GIS for a very wide array of applications
retail site selection & customer analysis
logistics: vehicle tracking & routing
natural resource exploration (petroleum, etc.)
precision agriculture
civil engineering and construction
Military and defense
Battlefield management
Satellite imagery interpretation
scientific research employs GIS
geography, geology, botany
anthropology, sociology, economics, political science
Epidemiology, criminology
9. 1.9
Examples of applied GISExamples of applied GIS
Civil Engineering/Utility
Locating underground facilities
Designing alignment for freeways, transit
Coordination of infrastructure
maintenance
Business
Demographic Analysis
Market Penetration/ Share Analysis
Site Selection
Education Administration
Attendance Area Maintenance
Enrollment Projections
School Bus Routing
Real Estate
Neighborhood land prices
Traffic Impact Analysis
Determination of Highest and Best Use
Health Care
Epidemiology
Needs Analysis
Service Inventory
Urban Planning, Management
& Policy
Zoning, subdivision planning
Land acquisition
Economic development
Code enforcement
Housing renovation programs
Emergency response
Crime analysis
Tax assessment
Environmental Sciences
Monitoring environmental risk
Modeling stormwater runoff
Management of watersheds,
floodplains, wetlands, forests,
aquifers
Environmental Impact Analysis
Hazardous or toxic facility siting
Groundwater modeling and
contamination tracking
Political Science
Redistricting
Analysis of election results
Predictive modeling
10. 1.10
Knowledge Base for GISKnowledge Base for GIS
GIS
Application Area:
public admin.
planning
geology
mineral exploration
forestry
site selection
marketing
civil engineering
criminal justice
surveying
Computer
Science/MIS
graphics
visualization
database
system administration
security
Geography
and related:
cartography
geodesy
photogrammetry
landforms
spatial statistics.
The convergence of technological fields and
traditional disciplines.
12. 1.12
The GIS Data Model:The GIS Data Model:
ImplementationImplementation
Geographic Integration of InformationGeographic Integration of Information
Digital Orthophoto
Streets
Hydrography
Parcels
Buildings
Zoning
Utilities
Administrative Boundaries
• Data is organized by layers, coverages or themes (synonomous concepts), with each
layer representing a common feature.
• Layers are integrated using explicit location on the earth’s surface, thus geographic
location is the organizing principal.
13. 1.13
The GIS Model: exampleThe GIS Model: example
roads
hydrology
topography
Here we have three layers or themes:
--roads,
--hydrology (water),
--topography (land elevation)
They can be related because precise
geographic coordinates are recorded for
each theme.
longitude
latitude
longitude
longitude
latitude
latitude
Layers are comprised of two data types
•Spatial data which describes location
(where)
•Attribute data specifing what, how
much,when
Layers may be represented in two ways:
•in vector format as points and lines
•in raster(or image) format as pixels
All geographic data has 4 properties:
projection, scale, accuracy and resolution
14. 1.14
Spatial and Attribute DataSpatial and Attribute Data
Spatial data (where)
specifies location
stored in a shape file, geodatabase or similar geographic file
Attribute (descriptive) data (what, how much, when)
specifies characteristics at that location, natural or human-created
stored in a data base table
GIS systems traditionally maintain spatial and attribute data
separately, then “join” them for display or analysis
for example, in ArcView, the Attributes of … table is used to link a
shapefile (spatial structure) with a data base table containing attribute
information in order to display the attribute data spatially on a map
15. 1.15
Representing Data withRepresenting Data with RasterRaster andand VectorVector
ModelsModels
Raster Model
area is covered by grid with (usually) equal-sized, square cells
attributes are recorded by assigning each cell a single value based on
the majority feature (attribute) in the cell, such as land use type.
Image data is a special case of raster data in which the “attribute” is a
reflectance value from the geomagnetic spectrum
cells in image data often called pixels (picture elements)
Vector Model
The fundamental concept of vector GIS is that all geographic features in
the real work can be represented either as:
points or dots (nodes): trees, poles, fire plugs, airports, cities
lines (arcs): streams, streets, sewers,
areas (polygons): land parcels, cities, counties, forest, rock type
Because representation depends on shape, ArcView refers to files containing
vector data as shapefiles
16. 1.16
0 1 2 3 4 5 6 7 8 9
0 R T
1 R T
2 H R
3 R
4 R R
5 R
6 R T T H
7 R T T
8 R
9 R
Real World
Vector Representation
Raster Representation
Concept of
Vector and Raster
line
polygon
point
18. 1.18
Projection, Scale, Accuracy andProjection, Scale, Accuracy and
ResolutionResolution
the key properties of spatial datathe key properties of spatial data
Projection: the method by which the curved 3-D surface of the earth is
represented by X,Y coordinates on a 2-D flat map/screen
distortion is inevitable
Scale: the ratio of distance on a map to the equivalent distance on the
ground
in theory GIS is scale independent but in practice there is an implicit range
of scales for data output in any project
Accuracy: how well does the database info match the real world
Positional: how close are features to their real world location?
Consistency: do feature characteristics in database match those in real world
is a road in the database a road in the real world?
Completeness: are all real world instances of features present in the database?
Are all roads included.
Resolution: the size of the smallest feature able to be recognized
for raster data, it is the pixel size
19. 1.19
Integrated analysis of Spatial and Attribute DataIntegrated analysis of Spatial and Attribute Data
Analysis of spatial data can be defined as computing from the
existing, stored spatial data that provides new insight.
Functions of this kind operate on the spatial and non-spatial
attributes of data can be grouped in to following groups:
Classification, retrieval, and measurement functions
• Allows to assign features to a class on the basisis of attribute values or
ranges.
• Retrieval of particular field based on the attribute value
• Measurement functions allow the cal of distances, length, are, etc..
Overlay functions
• Combination of two or more layers comaparing them position byy position,
and treating the areas of overlap and non-overlap(to observe union,
intersection and change detection etc.)
Neighbourhood functions
Operates on vicinity of given features which involves the near by features.
Connectivity function
• Evaluates a characteristic of a set of connected spatial units.
• Network functions are used to compute over connected line, features that
make up a network.
20. 1.20
The presentation of spatial data, whether in print or on-screen in
maps or in tabular displays or as raw data is closely related to the
disciplines of cartography, printing, and publishing.
The presentation may either be an end product(Atlas), or an
intermediate product (layout)
Spatial data presentation is done many ways
Cartography and scientific visualization make use of these methods and
devices to produce their products.
In both data capture and data presentation, the internet has become crucial
because of easy to use interface to repository of data sets
Method Device
Hard copy •Printer
•Plotter
•Film witer
Softcopy •Computer screen
Output of
digital data
sets
•Magnetic tape
•CD or DVD
•Storage
•The WWW
Spatial data presentationSpatial data presentation
21. 1.21
Software for GIS:Software for GIS: The Main PlayersThe Main Players
ESRI, Inc., Redlands, CA
clear market leader with about a third of the market
originated commercial GIS with their ArcInfo product in 1981
privately owned by Jack Dangermond, a legend in the field
Strong in gov., education, utilities and business logistics
MapInfo, Troy N.Y.
Aggressive newcomer in early 1990s, but now well-established.
Strong presence in business, especially site selection & marketing, and telecom
Intergraph (Huntsville, AL)
origins in proprietary CAD hardware/software
Older UNIX-based MGE (Modular GIS Environment) evolved from CAD
Current GeoMedia was the first true MS Windows-based GIS
strong in design, public works, and FM (facilities management), but weakening
Bentley Systems (Exton, PA)
MicroStation GeoGraphics, originally developed with Intergraph, is now their
exclusive and main product..
Strong in engineering; advertises itself as “geoengineering”
Autodesk (San Rafael, CA)
Began as PC-based CAD, but now the dominant CAD supplier
The main
two “pure
GIS”
companies.
22. 1.22
Software for GIS: other playersSoftware for GIS: other players
Vector GIS
Smallworld Systems
(Englewood, CO)
first to use OO (early
‘90s), but failed to
compete as established
vendors did same
Purchased by GE in 2000
emphasis on FM & utilities
Manifold
(CDA International Corp):
low cost, but low market
share
Maptitude
(Caliper Corp, Newton,
MA):
another low cost one
Raster GIS
• ERDAS/Imagine
– long established leader
– acquired by Leica Geosystems in 2001
• ER MAPPER
– aggressive newcomer originating in
Australia
• Envi,
– relative newcomer, radar specialization
– acquired by Kodak in 2000
• PCI--Geomatica
– long-term Canadian player
• CARIS
– newer Canadian entry
• GRASS (Rutgers Univ.)
– Classic old-timer originally developed by
US Army Construction Engineering
Research Lab(CERL) in Champaign, IL;
– army ended dev. & support in 1996 but
assumed by Baylor University.
• IDRSI (Clark Univ)
– pioneering, university-developed package
23. 1.23
productsproducts
ArcReader (“adobe acrobat” for maps) & ArcExplorer (spatial data viewer)
Free viewers for geographic data.
ArcGIS 9.x Desktop: two primary modules (MS only)
1. ArcMap: for data display, map production, spatial analysis, data editing
2. ArcCatalog: for data management and preview
ArcToolbox, for specialized data conversions and analyses, available as a window in both
Available capabilities within these modules are “tiered” in three levels
ArcView: viewing, map production, spatial analysis, basic editing:
ArcEditor: ArcView, plus specialized editing:
ArcInfo: ArcView & ArcEditor plus special analyses and conversions:
Extensions: for special apps.: Spatial Analyst, 3D Analyst, Geostatistics, Business Analyst,
etc.
ArcObjects: to build specialized capabilities within ArcMap or ArcCatalog using VB for
Applications
ArcGIS Workstation (for UNIX and MS)
the old command line ArcInfo 7.1
ArcGIS Engine (MS NT/2000/XP)
Set of embeddable GIS components (ArcObjects software objects) for use in building custom
applications
Runs under Windows, Unix and Linux, with support for Java, C++, COM and .NET
Replaces MapObjects which were based upon a previous generation of GIS objects
24. 1.24
ArcGIS Server: three tiers of capability
Data services: ArcSDE (Spatial Database Engine)
middleware to support spatial data storage in standard DBMS on server
Supports all major industry databases:
– Oracle, SQL-Server, IBM DB2, Ingres
Map services: ArcIMS (Internet Map Server)
Provides maps and simple query to a user without a desktop GIS
Accessed via web interface
Analytic services:
Permits the creation of server-based specialized GIS applications
Provides full range of GIS capabilities to a user without a desktop GIS
Accessed via web interface
(prior to 9.2 these were sold as three separate products)
ArcGIS On-line Services
On-line services made available on the Internet with a subscription
Normally charged on a “per transaction” basis, but can be flat fee
built and operated by ESRI (or other others), usually based on ArcGIS
Server
ESRI Product Line-up: ArcGIS server products (Fall 2007)
