Introduction to GIS systems

Introduction to GIS systemsIntroduction to GIS systems

By: Vivek SrivastavaBy: Vivek [email protected]@gmail.com

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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.

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OutlineOutline� Introduction

� Objective

� GI Technologies

� GI Systems

� GISystems Vs Others

� Examples of applied GIS applications

� Spatial and attribute data

� Integrating analysis with spatial and non-spatial data

� Software(s) for GIS

� Conclusions

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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

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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.

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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)

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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

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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

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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

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Knowledge Base for GISKnowledge Base for GIS

GIS

Application Area:public admin.planninggeologymineral explorationforestrysite selectionmarketingcivil engineeringcriminal justicesurveying

ComputerScience/MISgraphicsvisualization databasesystem administrationsecurity

Geographyand related:cartographygeodesyphotogrammetrylandformsspatial statistics.

The convergence of technological fields and traditional disciplines.

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GIGISS

Data

Decisions

Science

Managem

ent

(Geographic Information Systems)

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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.

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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

latit

ude

longitude

longitude

latit

ude

latit

ude

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

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Spatial and Attribute Data Spatial 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

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Representing Data with Representing Data with Raster Raster and and Vector Vector 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 ModelThe 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

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0 1 2 3 4 5 6 7 8 90 R T1 R T2 H R3 R4 R R5 R6 R T T H7 R T T8 R9 R

Real World

Vector RepresentationRaster Representation

Concept of Vector and Raster

line

polygon

point

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Images—dumb rasters(although they look good!)

Smart Raster—5 feet grids

Smart Vector—Pavement polygonsDumb ImagesDumb Images & Smart GIS & Smart GIS

DataData

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Projection, Scale, Accuracy and Projection, 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

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Integrated analysis of Spatial and Attribute Data Integrated 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.

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� 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

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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� First GIS product AutoCAD Map introduced in 1996� Primarily small business/small city customer base

The main two “pure GIS” companies.

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Software for GIS: other playersSoftware for GIS: other playersVector 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

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ESRI Product Line-up: ESRI Product Line-up: ArcGISArcGIS clientclient 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 editing2. ArcCatalog: for data management and previewArcToolbox, 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

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ArcGIS Server: three tiers of capabilityData 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)

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Clients

ESRI ArcGIS SystemESRI ArcGIS SystemESRI ArcGIS SystemESRI ArcGIS System

FilesFiles(Personal Geodatabase,(Personal Geodatabase,Shapefiles, Coverages,Shapefiles, Coverages,Grids, tins, etc)Grids, tins, etc)

ArcSDE ServicesDatabase storage/access

DatabasesDatabasesMulti-user GeodatabasesMulti-user Geodatabases(in Oracle, SQL Server,(in Oracle, SQL Server,

IBM DBII, etc)IBM DBII, etc)

ArcInfo ArcEditor ArcView

ArcIMS ServicesMap display & query

ArcExplorer Browser

InternetArcPad

ArcEngine/ArcObjectsApplicationDevelopment &Customization

c:\ ArcGIS WorkstationConsistent interfaceIncreasing capability

ArcMapArcCatalogArcToolbox

ArcMapArcCatalogArcToolbox

ArcMapArcCatalogArcToolbox

Source: ESRI with mods.Handheld/Wireless

$

ArcServer ServicesFull GIS analysis

THANK YOUTHANK YOU