Lecture 4: Spatial Data Models Flashcards
Object vs field view of the world
Object: Viewed as discrete features. Boundaries are well defined, each object is identified and described through the attribute table. Time changes represented as object location, shape and attribute changes (VECTOR MODEL/SYSTEM)
Field: Boundaries are fuzzy, each space partition is represented by a category or a value. Time changes is represented as a snapshot of cell changes (RASTER SYSTEM)
Topology
Science and mathematics studying properties of objects that do not change as the object is distorted.
What are the 3 fundamentals of vector data model
Point: one location (has a unique identifier)
Line: start and end point are connected
Polygon: each polygon has a label
What are the types of topology
Arc node topology: Line features can share endpoints
Polygon topology: Area features can share boundaries
Route topology: Line features can share segments with other line features
Region topology: Area features can overlap with other area features
Node topology: Line features can share endpoint vertices with point features
Point events: point features can share vertices with line features
Arc-node topology
Provides rule-based information of node connections to form lines
Join vs relate
Join:
Relate:
What ways are raster model displayed?
Triangle, hexagon, square
What are the challenges of encoding pixels?
Boundaries are fuzzy and hard to differentiate
Comparing vector and raster data models
Raster: Good for continuous data, better representation, good for data derived from remote sensing, application: forest change, landslide modelling
Vector: good for data with definite boundaries, network analysis capabilities are possible, best for graphic output, application: census analysis, routing problems
Sinton framework definition for vector and raster
In a vector system, time is controlled, space is measured and attributes are fixed. However, in the raster system, time is controlled, spaces is fixed and attribute is measured.
