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Spatial Databases- Introduction
Spring, 2015
Ki-Joune Li
STEMPNU
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Spatial Databases
What are on these images ?
How to represent, store, and retrieve
these data
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What are on these images?
These include Pixels Objects
Buildings, Roads, Symbols, etc Terrain
Height Data Non-Spatial Data
Name of Roads, Levels of Buildings, Capacity of Bridge, etc Relationship Between Objects
Goal of Spatial Databases Spatial databases are for representing, storing and retrieve
useful information from these data
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Properties and Challenges
Characteristics of Spatial Databases Spatial Data: Very Large Amount of Data
Example : more than 200 peta bytes for EOS Project Very complicated
Major Challenges How to represent sophisticated data: Representation How to store and manage a large amount of data: Management
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Issue I: Modeling
Example Building Spatial DB about Pusan City
What is Modeling? (cf. Schema Design) Modeling is much more important than schema design
Real World
Computer World
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Issue II: Management System
How to Handle Large Volume of Data Cost for Storage Media
Not very important and negligible Processing Time
I/O time How to reduce disk i/o time ?
DBMS Issue
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Spatial Databases ?
Spatial Databases ? Databases for spatial phenomena Spatial phenomena ?
Phenomena with spatial properties Spatial properties ?
What are spatial properties ? Example
Distance, Surface, Position (Coordinates) Adjacency, Connectivity
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Spatial Properties: Space
Depending on the Type of Space Euclidean Space
Flat space represented by Rn coordinate systems Point p is represented as an n-ary tuple (x1,x2, …, xn)
Road Network Space, Terrain Space, Indoor Space
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Open Space vs. Constraint Space
Open Space Distance is determined by the straight line connecting two points Example: Euclidean distance (or Euclidean metric)
Constrained Space Constraint on the straight line Distance is the length of shortest path detouring constraints Examples of Constraint
Road Network Indoor Terrain
n
i ii yxyxyxd1
2)(),(
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Example: Indoor Space
Emergency Bell A
401
W.C.
404
405
406
ElevatorStairs
p
Real distance
Emergency Bell B
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2-D space and 3-D space
3-D (cf. 2-D) More information Large amount of data
Example Rectangle: 4 vertices, 4 edges, and 1 face Cube: 8 vertices, 12 edges, and 6 faces
Complicated geometric processing Example
Overlapping of two polygons Overlapping of two polyhedrons
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2.5-D space
2.5-D space (cf. 3-D space) 3-D space: Solid Modeling 2.5-D space
Only one height value at any given point: f (x, y)=h
Field and 2.5-D Field: Terrain, Temperature distribution, etc.. 2.5-dimensional representation: Field Representation
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Spatio-Temporal Model
Spatial Model Stationary objects or phenomena Every object on the earth is moving!
Spatio-Temporal Model Object changing its location or shape according to time Discrete change
Example: Change of administrative boundary Continuous change
Example: Moving Objects, Meteorological Lines, Pollution Areas
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Topological and Geometric Properties
Geometry: Geo + Metry Geo: Earth, Space Metry
meter, metric, etc.. something to measure
Geo+Metry Something to measure in space Quantitative
m, m2, etc..
Topology Relationship between Spatial Objects Qualitative
adjacent, inside, left, right
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Spatial Database Building Procedure
Comparison with Software Life Cycle Comparison with Building Construction
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Spatial Database Building Procedure
Requirement Analysis Scope of databases: depends on applications Data Items, Attributes, Accuracy, etc.. Use-Case Diagram
Current State: As it is As it must be
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Spatial Database Building Procedure
Data Modeling Understanding the real world and application A very small piece of the real world
According to viewpoint Determined by applications
Drawing what you have understood in formal method Example. UML
4 steps Requirement Analysis Entity and Granularity Attributes Relationships
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Spatial Database Building Procedure
Data Collection Legacy System and Databases Interoperability and Standard Issue Data Generalization Metadata
Data Input Relies on Manual work Automatization
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Spatial Database Building Procedure
Quality Control Check the correctness of data
Maintenance Periodic Backup Updates
Equivalent to 30% of the total amount of data Determine the quality of DB