Algorithmic development of an optimal path computation model based on topographic map features

Path finding problems have attracted widespread research interests with different GIS-T applications such as Logistics applications, Infrastructure Planning and Travel Demand analysis. Previous researches have largely been conducted on developing shortest path algorithms in GIS. The conventional approach is to adopt the arc-node network model. For example, a road is represented by a centerline that is formed between the two road margins. The interconnection of these lines and their intersecting nodes will form a network ready for path finding and computation of relevant parameters. However, the generation and maintenance of a centerline network is difficult and tedious because these are not natural but imaginary features. Human judgment and manual digitization are essential and will differ between individual operators in the creation of these lines. To remedy the situation, an alternative approach is suggested that path finding method is independent of any arc-node data structure. The network model for such computation is solely based only on feature outlines as appeared on the topographic maps. In other words, outlines or symbology of relevant features for a certain path finding application like road margins, building outlines, subways will directly be used to model the path finding network. This paper will investigate the rationale and logistics to develop such a model first for pedestrian walking. A small set of digital map data from a very congested Hong Kong urban area will be used to evaluate the model reliability and efficiency.