Spatial Databases- Introduction

Spring, 2015

Ki-Joune Li

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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