19 research outputs found
Area topology for road extraction and topographic data validation
CISRG discussion paper ; 1
Line generalisation by repeated elimination of the smallest area
CISRG discussion paper ; 1
The Visvalingam algorithm: metrics, measures and heuristics
This paper provides the background necessary for a clear understanding of forthcoming papers relating to the Visvalingam algorithm for line generalisation, for example on the testing and usage of its implementations. It distinguishes the algorithm from implementation-specific issues to explain why it is possible to get inconsistent but equally valid output from different implementations. By tracing relevant developments within the now-disbanded Cartographic Information Systems Research Group (CISRG) of the University of Hull, it explains why a) a partial metric-driven implementation was, and still is, sufficient for many projects but not for others; b) why the Effective Area (EA) is a measure derived from a metric; c) why this measure (EA) may serve as a heuristic indicator for in-line feature segmentation and model-based generalisation; and, d) how metrics may be combined to change the order of point elimination. The issues discussed in this paper also apply to the use of other metrics. It is hoped that the background and guidance provided in this paper will enable others to participate in further research based on the algorithm
Approximation, generalisation and deconstruction of planar curves
CISRG discussion paper ; 1
Cartographic algorithms : problems of implementation and evaluation and the impact of digitising errors
CISRG discussion paper ;
Generalising roads on large-scale maps : a comparison of two algorithms
CISRG discussion paper ; 1
Towards sketch-based exploration of terrain : a feasibility study
CISRG discussion paper ; 1