Geographical Information System (GIS) Prof. A. K. Gosain gosain@civil.iitd.ernet.in
Definition of GIS GIS - Geographic Information System or a particular information system applied to geographical data Information System - set of processes, executed on raw data, to produce information useful in decisionmaking. Functions of an information system: observation, measurement, description, explanation, forecasting & decision making Uses both geographically referenced data as well as non-spatial data
Chain of Steps Data Collection & Processing Spatial Analysis Output Visualization COURSE EMPHASIS End-objective is Decision Making
CAD vs. GIS Function CAD GIS Geometric Design Dimensioning Spatial Operations Entity Data Operations Entity Symbolization Drawing/Map Layouts Programming 3-D Environment
Why is GIS Important? By putting maps and other kind of spatial information into digital form, connections between activities based on geographic proximity can be made. Looking at data geographically can often suggest new insights, explanations. These connections are often unrecognized without GIS, but can be vital to understanding and managing activities and resources.
Contributing Disciplines and Technologies GIS is a convergence of technological fields and traditional disciplines GIS has been called an "enabling technology" because of the potential it offers for the wide variety of disciplines which must deal with spatial data each related field provides some of the techniques which make up GIS many of these related fields emphasize data collection - GIS brings them together through integration, modeling and analysis as the integrating field, GIS often claims to be the science of spatial information
List of Disciplines Heritage Geography Data Collection Remote Sensing Photogrammetry Surveying Geodesy GPS Data Analysis Statistics Operations Research Computer Science Mathematics Data Reporting Cartography Computer Graphics
Geography (Heritage) broadly concerned with understanding the world and man's place in it long tradition in spatial analysis provides techniques for conducting spatial analysis
Remote Sensing images from space and the air are major source of geographical data remote sensing includes techniques for data acquisition and processing anywhere on the globe at low cost and consistent update potential many image analysis systems contain sophisticated analytical functions interpreted data from a remote sensing system can be merged with other data layers in a GIS
Photogrammetry photogrammetry is the source of most data on topography (ground surface elevations) used for input to GIS uses analytic techniques for making accurate measurements from aerial/space photographs and imageries,
Surveying provides high quality data on positions of land boundaries, buildings, etc data is usually based on ground surveys with theodolites and/or global positioning systems (GPS)
Geodesy source of high accuracy positional control for GIS, GPS, remote sensing and surveying concentrates on placing objects accurately in a global context
Statistics many statistical techniques are used for analysis statistics is important in understanding issues of error and uncertainty in GIS data many models built using GIS are also statistical in nature
Operations Research many applications of GIS require use of optimizing techniques for decision-making
Computer Science computer-aided design (CAD) provides software, techniques for data input, display and visualization, representation, particularly in 3 dimensions advances in computer graphics provide hardware, software for handling and displaying graphic objects, techniques of visualization database management systems (DBMS) contribute methods for representing data in digital form, procedures for handling large volumes of data, particularly retrieval and updation artificial intelligence aspects of computer systems are increasingly being used for data mining and many other functions such as designing maps, generalizing map features
Mathematics several branches of mathematics, especially geometry, algebra, and graph theory, are used in GIS system design and analysis of spatial data
Cartography concerned with the display of spatial information currently the main source of input data for GIS is maps provides long tradition in the design of maps which is an important form of output from GIS computer cartography (also called "digital cartography or "automated cartography") provides methods for digital representation and manipulation of cartographic features and methods of visualization
Major Areas of Application Land (parcels) (LIS) Facilities Management (FIS) Natural Resource & Environment Infrastructure Networking
Land Information Systems LIS zoning, subdivision plan review land acquisition environmental impact statements water quality management maintenance of ownership
Facilities Information Systems FIS FIS is aimed at integration of a Geographic Information System (GIS), Facilities Management System(FMS), and Maintenance Management System (MMS) Examples: locating and maintaining underground pipes, cables balancing loads in electrical networks facility management and maintenance
Natural Resource & Environmental management of rivers, floodplains, wetlands, agricultural lands, aquifers, forests, wildlife environmental impact assessment (EIA) geologic hazard studies viewshed analysis hazardous or toxic facility siting groundwater modeling and contamination tracking wildlife habitat analysis, migration routes planning
Infrastructure Networks address matching - finding locations given street addresses sewer routing water system routing electrical system routing vehicle routing and scheduling location analysis, site selection development of evacuation plans