Aggregating land-use polygons considering line features as separating map elements

ABSTRACT

Map generalization is the process of deriving small-scale target maps from a large-scale source map or database while preserving valuable information. In this paper we focus on topographic data, in particular areas of different land-use classes and line features representing the road network. When reducing the map scale, some areas need to be merged to larger composite regions. This process is known as area aggregation. Given a planar partition of areas, one usually aims to build geometrically compact regions of sufficient size while keeping class changes small. Since line features (e.g. roads) are perceived as separating elements in a map, we suggest integrating them into the process of area aggregation. Our aim is that boundaries of regions coincide with line features in such a way that strokes (i.e. chains of line features with small angles of deflection) are not broken into short sections. Complementing the criteria of compact regions and preserving land-use information, we consider this aim as a third criterion. Regarding all three criteria, we formalize an optimization problem and solve it with a heuristic approach using simulated annealing. Our evaluation is based on experiments with different parameter settings. In particular, we compare results of a baseline method that considers two criteria, namely compactness and class changes, with results of our new method that additionally considers our stroke-based criterion. Our results show that this third criterion can be substantially improved while keeping the quality with respect to the original two criteria on a similar level.

KEYWORDS:

• Map generalization
• area aggregation
• road networks
• strokes
• simulated annealing

Data availability

The data used in our experiments are derived from OpenGeodata.NRW at https://www.opengeodata.nrw.de/produkte/geobasis/lm/basis-dlm/. The particular data set is openly available in figshare at https://doi.org/10.6084/m9.figshare.12987710.v2. The data is provided by Geobasis NRW under the Data licence Germany - Zero - Version 2.0; https://www.govdata.de/dl-de/zero-2-0.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by Zoomless Maps: Models and Algorithms for the Exploration of Dense Maps with a Fixed Scale of the German Research Foundation (DFG) [grant number 5451/6-1]; Deutsche Forschungsgemeinschaft [5451/6-1].