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Prepared by Abzamiyeva Laura Candidate of the department of KKGU named after Al- Farabi

GIS DATA MODELS. Prepared by Abzamiyeva Laura Candidate of the department of KKGU named after Al- Farabi Kizilorda , Kazakstan 2012. Object. I ntroduction of GIS Data modeling . What is GIS ?.

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Prepared by Abzamiyeva Laura Candidate of the department of KKGU named after Al- Farabi

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  1. GIS DATA MODELS Prepared by Abzamiyeva Laura Candidate of the department of KKGU named after Al-Farabi Kizilorda, Kazakstan 2012

  2. Object • Introduction of GIS • Data modeling

  3. What is GIS ? “GIS is a computer-based system that provides the following four sets of capabilities to handle geo-referenced data: 1. Input 2. Data management (storage and retrieval) 3. Manipulation and analysis 4. Output.” (Aronoff, 1989)

  4. Data Input Database Query and Analysis Output and Visualization GIS Functional Modules

  5. What does GIS? GIS deals with objects, their attributes, and the relationships among the objects. The objects are stored in a database using geometric primitives (volumes, areas, lines, points), their attributes and the relationships between them (topology). →https://www.e-education.psu.edu/natureofgeoinfo/book/export/html/1604

  6. Characteristics of Geographic Data • Spatial data: features orientation shape, size & structure • Non-Spatial data: Information about various attributes like area, length & population

  7. Characteristics of Spatial Data • spatial reference • attributes • spatial relationships • temporal component • where? • what? • how? • when?

  8. Data Model • Data model represents the linkages between the real world domain of geographic data and the computer or GIS representation of these features. It helps (Marble, 1982) • To organize a systematic file structure • Abstracts the real world into properties which are perceived by a specific application

  9. How to represent the really data? • ?

  10. GIS structures as representations of reality • Two approaches have been widely adopted for representing • the spatial & attribute information within a GIS • A composite model (raster) • Geo-relational model (vector)

  11. Implementation Models Field View • tessellation (raster, grid) • simple data structure • difficult to represent topology • suitable for image processing functions Object View • vector (topological vector model) • efficient representation of topology • complex data structure • certain functions are difficult to implement

  12. Real (and Virtual) World Models Maps Databases 10100100111 Visualization Representation Generalization Storage

  13. Maps • Best known conventional model • Two-dimensional • Static • Visualization as their major function • Small-scale = less detail, larger area (e.g. 1:1.000.000) • Large-scale = more detail, smaller area (e.g. 1:10.000) • Generalization (scale-dependant)

  14. Databases • Store representations of spatial phenomena in the real world • Data models are languages used to define a database • The complete database definition is the database schema • Spatial databases are scaleless and seamless

  15. spatial data models • two fundamental approaches: • raster model • vector model

  16. a raster view of the world... Features Raster Tessellation Sampling

  17. raster model The entity information is explicitly recorded for a basic data unit (cell, grid or pixel)

  18. vector model • In a vector-based GIS data are handled as: • Points X,Y coordinate pair + label • Lines series of points • Areas line(s) forming their boundary (series of polygons) line feature area feature point feature

  19. vector model

  20. vector model

  21. layers in a raster model Layer 1 Layer 2

  22. Reference: →http://www- →MapServer →OpenLayers

  23. THANK YOU !

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