3. Data Models

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Lecture 07 Data Representation (V)
Topics
3. Data Models 3.3 Spatial data models
3.3.1 Raster Data Models 3.3.2 Vector
Data Models
Readings on the topics
Chapter 8 in the text, pp. 183-184 Chapter 6 in
Aronoffs (1993), pp. 172-177
Other readings
Chapter 3 in Bonham-Carters (1994), pp.
68-71 Chapter 3 in Burrough and McDonnell (1998),
pp. 57-64
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Lecture 07 Data Representation (V)
3. 3 Spatial Data Models
3.3.2 Vector data models A. Vector
representation The basic concept
(The Vector Representation Figure)
The representation of point, linear and area
features (The point, line, area in
vector figure)
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B. Terminology Vertex Node
Arc Polygon Label
point C. Spatial Topology Spatial
relationships of the basic geometric elements
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D. Types of models 1) Entity by
Entity (Spaghetti) Model a) definition
b) Versions of spaghetti models
(1) Simple lists (The
simple lists figure) (2) Point
directory (The point directory
figure) c) A comparison of spaghetti
models (The Spaghetti comparison
figure)
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E. Summary (1) Geographic features
are treated as individual objects The
spatial boundary is explicitly coded (2) No
relationships among objects Spatial
topology among features are not explicitly coded

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Questions
1. How does a vector data model represent spatial
data? How does it represent a point feature,
a linear feature, and an area feature? 2. What
are the advantages and disadvantages of the
vector data model? 3. What is an arc and
what is a node? Can any point be a node?
what is the difference between arc and a polyline
(a line made of multiple straight
segments)? 4. How are the three basic geometric
elements are used to capture spatial topology
in a topological data model? 5. What is the main
difference the simple list data model and the
point directory data model? Why dont we
consider them to be topological data models?