Prepared by Abzamiyeva Laura Candidate of the department of
KKGU named after Al-Farabi Kizilorda, Kazakstan 2012
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Object Introduction of GIS Data modeling
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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) What is GIS ?
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GIS Functional Modules Database Query and Analysis Output and
Visualization Data Input
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https://www.e-education.psu.edu/natureofgeoinfo/book/export/html/1604https://www.e-education.psu.edu/natureofgeoinfo/book/export/html/1604
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).
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Characteristics of Geographic Data l Spatial data: features
orientation shape, size & structure l Non-Spatial data:
Information about various attributes like area, length &
population
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l spatial reference l attributes l spatial relationships l
temporal component Characteristics of Spatial Data where? what?
how? when?
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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 structureTo organize a systematic file
structure Abstracts the real world into properties which are
perceived by a specific applicationAbstracts the real world into
properties which are perceived by a specific application
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How to represent the really data? ?
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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) A
composite model (raster) Geo-relational model (vector)
Geo-relational model (vector)
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Implementation Models Field View l 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
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Real (and Virtual) World Models 10100100111 Maps Databases
Visualization Representation Generalization Storage
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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) Maps
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Databases l Store representations of spatial phenomena in the
real world l Data models are languages used to define a database l
The complete database definition is the database schema l Spatial
databases are scaleless and seamless
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spatial data models l two fundamental approaches: l raster
model l vector model
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a raster view of the world... Tessellation Raster Features
Sampling
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raster model The entity information is explicitly recorded for
a basic data unit (cell, grid or pixel)
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vector model In a vector-based GIS data are handled as:
PointsX,Y coordinate pair + label Linesseries of points
Areasline(s) forming their boundary (series of polygons) line
feature area feature point feature