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A multi-agent System Approach for Feature-
driven Generalization of isobathymetric Line
Xunruo Zhang, Eric Guilbert
The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
crystal_zxr@hotmail.com
Abstract
Generalization is an important branch in cartography. This process
abstracts a map for emphasizing important items and increasing its legibility.
On a nautical chart, the purpose is also to emphasize navigational hazards
and main navigation routes. Therefore, the cartographer not only adapts
the amount of information to the scale of the chart but also selects the
information according to the types of features on the seabed and their impor-
tance to the navigator. Features are characterized by the isobaths. Methods
usually applied on contours for topographic maps cannot be applied on
isobaths as they do not take information about features into consideration
and a new strategy coordinating different generalization operators must be
defined for nautical charts. This paper focuses on isobaths generalization
and introduces a new approach based on a multi-agent system. It first in-
troduces the characteristics and constraints of isobath generalization. Then
it presents the multi agent model where features and isobaths are repre-
sented by agents at different levels. Possible actions performed by each
agent are presented with measures for evaluating their results according to
generalization constraints.
1- Introduction
A nautical chart is a plane representation of the seabed. It is used by navi-
gators to establish their route and ensure safety of navigation. On the chart,
the seabed is described by soundings (depth points) and isobathymetric
lines (contour lines of equal depth). In order to present a useful and legible
chart, soundings and lines must be generalized with regard to their rele-
vance to the map purpose and scale. Automatic generalization of contour
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