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  • 1. www.mcsmapping.com August 25, 2010 Presentation Outline • History • Definition • Components GIS • Applications Fundamentals • Data models • Raster Data • Vector Data © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 1 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 2 Where did GIS come from? A Brief History of GIS • GIS is built upon knowledge from geography, • GIS’s origins lie in thematic cartography (manual map overlay) • Computer cartography advances in 1950s and 1960s cartography, computer science and mathematics • Early influential data sets were the World Data Bank and the • Geographic Information Science is a new GBF/DIME files. Early systems were CGIS, MLMIS, GRID and LUNR • The Harvard University ODYSSEY system was influential due to its interdisciplinary field built out of the use and topological arc-node (vector) data structure theory of GIS • GIS was significantly altered by (1) the PC and (2) the workstation • During the 1980s, new GIS software could better exploit more advanced hardware • User Interface developments led to GISs vastly improved ease of use during the 1990s • During the 1980s, new GIS software could better exploit more advanced hardware © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com Defining GIS Geographic Information Systems (GIS) • Different definitions of a GIS have evolved in different • The common ground between information processing areas and disciplines and the many fields using spatial analysis techniques. (Tomlinson, 1972) • All GIS definitions recognize that spatial data are unique because they are linked to maps (Space matters!) • A powerful set of tools for collecting, storing, retrieving, transforming, and displaying spatial data from the real • A GIS at least consists of a database, map information, world. (Burroughs, 1986) and a computer-based link between them • A computerized database management system for the capture, storage, retrieval, analysis and display of spatial data. (NCGIA, 1987) • A decision support system involving the integration of spatially referenced data in a problem solving environment. (Cowen, 1988) © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 6Confidential 1
  • 2. www.mcsmapping.com August 25, 2010 An Inelegant Definition for GIS GIS: intuitive description A system of integrated computer-based tools for end-to- • A map with a database behind it. end processing (capture, storage, retrieval, analysis, • A virtual representation of the real world and its display) of data using location on the earth’s surface for infrastructure. interrelation in support of operations management, • A consistent “as-built” of the real world, natural and decision making, and science. manmade Which is • set of integrated tools for spatial analysis • queried to support on-going operations • encompasses end-to-end processing of data(capture, • summarized to support strategic decision making and storage, retrieval, analysis/ modification, display) policy formulation • uses explicit location on earth’s surface to relate data • analyzed to support scientific inquiry • aimed at decision support, as well as on-going operations and scientific inquiry © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 7 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 8 Why Study GIS? The major areas of GIS application • 80% of local government activities estimated to be geographically based • Local Government – plats, zoning, public works (streets, water supply, sewers), garbage – Public works/infrastructure management (roads, water, sewer) collection, land ownership and valuation – Planning and environmental management • a significant portion of state government has a geographical component – natural resource management – property records and appraisal – highways and transportation • Real Estate and Marketing-Retail site selection, site evaluation • businesses use GIS for a very wide array of applications • Public safety-Crime analysis, fire prevention, emergency – retail site selection & customer analysis management – logistics: vehicle tracking & routing • Natural resource exploration/extraction - Petroleum, minerals, – natural resource exploration (petroleum, etc.) quarrying – precision agriculture • Transportation- Airline route planning, transportation modeling – civil engineering and construction • scientific research employs GIS • Public health and epidemiology – geography, geology, botany • The Geospatial Industry - Data development, application – anthropology, sociology, economics, political science development, programming – Epidemiology, criminology © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 9 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 10 Advantages of GIS Examples of Applied GIS 1. The potential and substantial benefits of using GIS make it a very • Urban Planning, Management & Policy important tool making the work of any organization easier and more – Zoning, subdivision planning – Land acquisition productive. Some of the potential benefits of GIS are: – Economic development 2. Opportunity to reduce sets of manual maps held and associated storage – Code enforcement costs. – Housing renovation programs 3. Faster and more extensive access to geographic information. – Emergency response – Crime analysis 4. Improved analysis e.g. Of areas, distances, patterns, etc. – Tax assessment 5. Better communication of information to public officers, members. • Environmental Sciences – Monitoring environmental risk 6. Improved quality of services. – Modeling storm water runoff 7. Better targeting and coordination of services. – Management of watersheds, floodplains, wetlands, forests, 8. Improved productivity in providing public information. aquifers – Environmental Impact Analysis 9. Improved efficiency in updating maps. – Hazardous or toxic facility sites 10. The ability to track and monitor growth and development over time – Groundwater modeling and contamination tracking 11. Improved ability to aggregate data for specific sub areas. • Political Science – Redistricting 12. Thus GISs have become indispensable tools for governance, commerce, – Analysis of election results and environmental and social science. – Predictive modeling © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 11 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 12Confidential 2
  • 3. www.mcsmapping.com August 25, 2010 Examples of Applied GIS contd. Components of 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 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 13 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 14 GIS System Architecture and Components The GIS Data Model: Implementation Administrative Boundaries Utilities Data Input Zoning Buildings Parcels Geographic Query Input Hydrography Database Streets Digital Orthophoto • Data is organized by layers, coverages or themes (synonomous Output: Display Transformation concepts), with each layer representing a common feature. and Reporting and Analysis • Layers are integrated using explicit location on the earth’s surface, thus geographic location is the organizing principal. © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 15 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 16 The GIS Model: example The GIS Model: example © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 17 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 18Confidential 3
  • 4. www.mcsmapping.com August 25, 2010 The GIS Model: example Spatial and Attribute Data Here we have three layers or themes: • Spatial data (where) --roads, – specifies location roads --hydrology (water), – stored in a shape file or similar geographic file --topography (land elevation) longitude They can be related because precise geographic • Attribute (descriptive) data (what, how much, when) coordinates are recorded for each theme. – specifies characteristics at that location, natural or human- created Layers are comprised of two data types – stored in a data base table hydrology •Spatial data which describes location (where) •Attribute data specifying what, how much, when • GIS systems traditionally maintain spatial and attribute data longitude separately, then “join” them for display or analysis Layers may be represented in two ways: – for example, in QGIS, the Attributes of … table is used to join •in vector format as points and lines a shapefile (spatial structure) with a data base table containing •in raster(or image) format as pixels attribute information in order to display the attribute data topography spatially on a map All geographic data has 4 properties: projection, scale, accuracy and resolution longitude © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 19 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 20 Representing Data Concept of Vector and Raster Real World 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) Raster Representation Vector Representation Vector Model 0 1 2 3 4 5 6 7 8 9 0 R T point The fundamental concept of vector GIS is that all geographic features in the real 1 R T work can be represented either as: 2 H R • points or dots (nodes): trees, poles, fire plugs, airports, cities 3 R line • lines (arcs): streams, streets, sewers, 4 R R 5 R • areas (polygons): land parcels, cities, counties, forest, rock type 6 R T T H Because representation depends on shape, QGIS refers to files containing vector 7 R T T polygon data as shapefiles 8 R 9 R © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 21 Raster & Vector Data The key properties of spatial data Advantages of raster data • Projection: the method by which the curved 3-D surface of the 1. Simple data structure earth is represented by X,Y coordinates on a 2-D flat map/screen 2. Easy and efficient overlaying – distortion is inevitable 3. Compatible with RS imagery • Scale: the ratio of distance on a map to the equivalent distance on 4. High spatial variability is efficiently represented the ground 5. Simple for own programming – in theory GIS is scale independent but in practice there is an 6. Same grid cells for several attributes implicit range of scales for data output in any project • Accuracy: how well does the database info match the real world Advantages of vector data – Positional: how close are features to their real world location? 1. Compact data structure – Consistency: do feature characteristics in database match 2. Efficient for network analysis those in real world -is a road in the database a road in the real world? 3. Efficient projection transformation – Completeness: are all real world instances of features present 4. Accurate map output. 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 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 23 © Magendhiran Consultancy Services. All rights reserved. www.mcsmapping.com 8/25/2010 24Confidential 4