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. 190-194 (oo) Other readings Chapter 3 in Burrough and McDonnell’s 1998, pp. 71-74

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

3.4.2 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

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

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

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)

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?