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Geographic information system

Geographic information system. Rıfat Ordulu. What is geographic information system?. Wherever a geographic information is manipulated, integrated, stored, edited, analyzed, shared and displayed, we are talking about GIS (geographic information system)

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Geographic information system

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  1. Geographic information system RıfatOrdulu

  2. What is geographic information system? • Wherever a geographic information is manipulated, integrated, stored, edited, analyzed, shared and displayed, we are talking about GIS (geographic information system) • Data representation: roads, land use, elevation, trees, waterways, etc.

  3. Types of objects • Discrete objects: houses, trees, etc. • Continues objects: rainfall amount, elevation.

  4. Methods to store data • Raster images • Vector • Point clouds

  5. Raster Method • Bitmap technology (as we already now) • Pixel by pixel values • Special data to the pixels (temperature)

  6. Vector Method • Points, Lines, Polygons • All of them are linked to a row in db • Example; storage of a house • House’s population • Height • Price • ….

  7. Vector Method

  8. Comparison

  9. How to keep records? • Flat files and spreadsheets • Hierarchical files • Relational files

  10. Flat Files and Spreadsheets • Simplest method for storing data • Expanding the number of fields is a problem • May require reprogramming • Insert operation is time consuming if number of fields is high • No flexibility

  11. Hierarchical Files • Parent-child, one-to-many relationship • One field is key to all records • Associates the records with similar attributes • If relationships clearly defined and if we have standardized queries, we will come up efficient results • Must access the master record in order to go downwards

  12. Relational Files • Connects records without a key or a pointer • Matrices of tables • Tables having common link • Flexible • Most popular for GIS • Close to SQL

  13. Comparison

  14. Representing Relationships • Spatial Relationships • Relative location, direction and movement from place to place, etc. • Functional Relationships • Road network, house ownership etc. • Logical Relationships • No land may be permitted to be zoned for residential use if it is within rivers three-year flood plain • If-then, and-or logic.

  15. Topological Relationships • Most useful in spatial databases • Determines how and where points and lines connect • Usage example; to find optional routes for emergency vehicles

  16. How connections are stored • First; location of all nodes • Second; defining arcs (from node to node with direction) • Third; defining polygons using arcs

  17. Object-Oriented Databases • Grouping the attributes of an object into sub objects • For example; instead of using points, you divide it into house, office, resident, forest etc. • Big work load, but well organized

  18. E-R • E-R is the most important term when building a GIS database • We have many entities and relations in GIS databases • For example; a house may be related to an owner, related to a place, related to a person who lives in there, related to a type of house etc.

  19. Example Schema

  20. References • Database Concepts, Kenneth E.Foote and Donald J.Huebner, Department of Geography, University of Texas at Austin, 1996. • GIS Database Development and Exchange: Interaction Mechanisms and MotivationsZoricaNedovic-Budic, Jeffrey K. Pinto, and Lisa Warnecke • Relational Database Management Systems,Database Design, and GIS. Tim Haithcoat ,University of Missouri,Columbia • A GIS DATABASE DESIGN FOR URBAN POVERTYMANAGEMENT, Felicia Olufunmilayo AKINYEMI, Nigeria • UPDATED GIS DATABASE DESIGN:Geodatabase ModelPrepared by:Michael Baker Jr., Inc.Virginia Beach, Virgini

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