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Introduction to GIS systems


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Introduction to GIS systems

  1. 1. Introduction to GIS systemsIntroduction to GIS systems By: Vivek SrivastavaBy: Vivek Srivastava
  2. 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.
  3. 3. 1.3 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
  4. 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. 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. 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. 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. 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. 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. 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.
  11. 11. 1.11 SS Data Decisions Science M anagem ent (Geographic Information Systems)
  12. 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. 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. 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. 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. 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
  17. 17. 1.17 Images—dumb rasters (although they look good!) Smart Raster—5 feet grids Smart Vector—Pavement polygonsDumb ImagesDumb Images & Smart GIS& Smart GIS DataData
  18. 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. 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. 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. 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. 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. 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. 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)
  25. 25. 1.25 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 Services Database storage/access DatabasesDatabases Multi-user GeodatabasesMulti-user Geodatabases (in Oracle, SQL Server,(in Oracle, SQL Server, IBM DBII, etc)IBM DBII, etc) ArcInfo ArcEditor ArcView ArcIMS Services Map display & query ArcExplorer Browser Internet ArcPad ArcEngine/ ArcObjects Application Development & Customization c: ArcGIS Workstation Consistent interface Increasing capability ArcMap ArcCatalog ArcToolbox ArcMap ArcCatalog ArcToolbox ArcMap ArcCatalog ArcToolbox Source: ESRI with mods. Handheld/Wireless $ ArcServer Services Full GIS analysis