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- Zhang, Qingnian
(författare)
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Labeling dense maps for location-based services
- 2005
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Ingår i: Web and Wireless Geographical Information Systems (Lecture Notes in Computer Science). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0302-9743 .- 1611-3349. ; 3428, s. 195-205
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Spatial information is often presented as maps in location-based services, which makes it necessary to label cartographic features in real time. Features may be dense all over the map, or in certain areas. Owing to the limited free spaces, it is always difficult to label dense features. Aiming to utilize free spaces efficiently, this paper proposed a density-based method of labelling dense features. The method placed labels of dense features earlier than sparse ones, so that free spaces were allotted to dense features before consumed by sparse features. An efficient algorithm was developed for map labelling in real time. We implemented this method in a Java environment. A case study shows sound cartographic results and acceptable efficiency of the labelling.
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- Zhang, Qingnian, et al.
(författare)
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Real-time map labelling for mobile applications
- 2006
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Ingår i: Computers, Environment and Urban Systems. - : Elsevier BV. - 0198-9715. ; 30:6, s. 773-783
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Tidskriftsartikel (refereegranskat)abstract
- It is essential to label roads, landmarks, and other important features on maps for mobile applications to help users to understand their location and the environment. This paper aims to examine real-time map labelling methods suitable for the small screen on mobile devices. A slider method with a continuous search space was proposed to sequentially label both line and point features. The method starts with defining a range box for possible locations of the label. Then a search is performed, and the range box is reduced, if there are any cartographic objects that overlap the range box. Finally, the label is placed, at the best possible position in the reduced range box according to normal cartographic preferences, where it does not obscure any cartographic object. We implemented this method in a Java environment using the open source library JTS Topology Suite. A case study showed sound cartographic results of the labelling and acceptable computational efficiency. (c) 2006 Elsevier Ltd. All rights reserved.
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