Gerneralisation Flashcards
Generalisation
Need to maintain graphic legibility
Need to retain general characteristics
Consider relative importance
Graphical generalisation
Guidelines setting out priorities
Traditional down at compilation stage
Problems with Manual processes
Give different results
Time consuming
Inconsistent
Automation process
Improves consistency - you know exactly what’s happening because computers follow rules
Correct information has to be inputted
Can store different representation of the same feature
9 stages of generalisation
- elimination
- Simplification
- combination/aggregation
- typify cation (selective omission)
- collapse
- exaggeration
- displacement
- smoothing/aesthetic refinement
- combination operations
Elimination
Things below a certain threshold seems to get removed on a smaller scale. Helps to essentially declutter
Simplification
Cannot get as much detail as scale increases - need to simplify boundaries. The general characteristic must be retained
Combination/aggregation
The individual points in an area is shown as a cluster - move from individual points to an area = catastrophic change.
Buildings shown in black to retain balance between buildings and non-buildings.
Not very popular in European cartography
Typification (selective omission)
Rather eliminating individual features, enough is maintained to to retain general idea of the feature I.e tributaries
Exaggeration
A feature on small scale maps may be represented on a larger scale. I.e. The size ratio of a footpath.
This has consequences as it takes up more space. Less things can be represented. This will lead to displacement
Displacement
Adjustments may occur in order to see particular features if they are separated. In order to meet needs of a map, displacement occurs
Smoothing/aesthetic refinement
To make the map legible. Keeping everything as close to its original position. Makes lines straighter, rotation of symbols
Combinations of operations
These operations have to be combined and cannot be completed in isolation. This is to ensure that the legibility of the map is retained. Small collection of indivisible islands are grouped to portray a collection of representative of islands
Key issues
Need to focus on the representation of reality. To easy to focus on geometric problems
May be easy to generalise one feature but the interaction between other features need to be considered. I.e. Contours cannot cross and contours and drainage
