UNIT 48 - LINE GENERALIZATION

UNIT 48 - LINE GENERALIZATION

UNIT 48 - LINE GENERALIZATION

A. INTRODUCTION

B. ELEMENTS OF LINE GENERALIZATION

Simplification

Smoothing

Feature Displacement

Enhancement/Texturing

Merging

C. JUSTIFICATIONS FOR SIMPLIFYING LINEAR DATA

Reduced plotting time

Reduced storage

Problems with plotter resolution when scale is reduced

Processing

D. LINEAR SIMPLIFICATION ALGORITHMS

Independent Point Routines

Local processing routines

Unconstrained extended local processing routines

Constrained extended local processing routines

Global routines

E. MATHEMATICAL EVALUATION OF SIMPLIFICATION

F. LINEAR SMOOTHING

REFERENCES

Buttenfield, B.P., 1985. "Treatment of the Cartographic Line," Cartographica 22(2):1-26.

Douglas, D.H. and T.K. Peucker, 1973. "Algorithms for the Reduction of the Number of Points Required to Represent a Line or Its Character," The American Cartographer 10(2):112-123.

McMaster, R.B., 1987, "Automated Line Generalization," Cartographica 24(2):74-111.

McMaster, R.B., 1987. "The Geometric Properties of Numerical Generalization," Geographical Analysis 19(4):330-346.

McMaster, R.B.,1989. "The Integration of Simplification and Smoothing Algorithms," Cartographica 26(1).

Peucker, T.K., 1975. "A Theory of the Cartographic Line," Proceedings, Second International Symposium on Computer- Assisted Cartography, AUTO-CARTO-II, September 21-25, 1975 U.S. Dept. of Commerce, Bureau of Census and ACSM, pp. 508-518.

White, E., 1985. "Assessment of Line-Generalization Algorithms Using Characteristic Points," The American Cartographer 12(1):17-27.

DISCUSSION/EXAMINATION QUESTIONS

1. Discuss the differences between sequential and global approaches to line simplification.

2. What are the five generalization operators for digital line data? Discuss each one of these and give examples.

3. Using a series of diagrams, discuss the procedure used by the Douglas algorithm.

4. Discuss the different approaches you might use to evaluate the effectiveness of line simplification procedures and the advantages and disadvantages in each case.


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