1. Lecture 10: Data Representation (VIII)
Topics
3. Data Models
3.4 Linking attribute data with spatial data
3.5 Recent development in data models
Readings on the topics
Chapter 8 in the text, pp (oo)
Other readings
Chapter 3 in Burrough and McDonnell’s 1998, pp

2. Outlines 3. 4 Linking Attribute Data with Spatial Data:
3.4.1 The vector approach:
1) Representation:
(The Linking in Vector Figure)
2) Spatial queries:
a) Show Smith’s farmlands.
b) Find all farmers whose lands are next to Bow River
3) Practice:
Compute the average household income of the farmers
along the Bow River as if you were a computer

3. 3.4.2 The raster approach:
(The Raster Representation Figure)
One raster layer for one attribute type
3.4.3 The TIN Approach:
Mostly used for representing elevation data

4. 3.5 Recent development in data models
2.5.1 Object oriented data model:
1) what is an object and what is an object class
Object is an identifiable and self-contained entity. There
are two components in describing an object: properties
(attributes) and behaviours (methods).
Object class is a group of objects of the same type
2) Aspects of object-oriented data modeling
Encapsulation
Inheritance
Polymorphism

5. 3.5 Recent development in data models (continued…)
2.5.2 Temporal data models:
1) Evolution of geographic features
a) Aspects of evolution
Creation and termination
Attribute change over time
Location (boundary) change over time
Spatial topology change over time
(The Change Examples Figure)
b) Type of evolution
Continuous (gradual) evolution
such as forest fires
Discrete (abrupt) evolution
such as change of ownership of land parcels

6. 3.5 Recent development in data models (continued…)
2.5.2 Temporal data models: (continued…)
2) Strategies of representation
a) Time slices
time stamped snapshots
(for continuous evolution)
b) Event-based
time stamp and record only changes
(for discrete evolution)

7. Questions:
1. How can spatial topology be used to answer spatial queries?
2. What is the difference between vector data model and raster data model in representing attributes?
3. What is advantage for using object oriented data models?
4. What are the different type of evolution of geographic features? How can each type be represented?