An Experimental Evaluation Of The Relativity Principles For Schematic Network Maps Design

Schematic network maps are abstraction for geographic networks in reality. They are able to preserve the major information of the network in a reader-friendly way and are widely used in geographic networks such as traffic, electronic and hydrology. Algorithms have been developed by researcher from various disciplines to generate the schematic network maps automatically, but the results are less satisfactory comparing to those designed by artists. The key of a successful schematic network map lies in the designing rules. The relative principle is a critical part of it. However, among those automated algorithms, none of them have paid enough attention to this principle.The relative principle in designing a schematic network map includes the principle of relativity in position and the principle of relativity in length, which means comparing to the original geographic network, the schematic network map should preserved the corresponding position between nodes and corresponding length of the arcs. This principle is approved by professional cartographic researchers who have a lot of experience in mapping, but there is still a lack of objective ground and validation. Furthermore, the relative principle has not being consider in the automated algorithms to generate schematic network maps yet. For those insufficiency, the thesis discussed several key problems of relative principle in schematic network designation. The major contributions are as follows:1) With the help of several examples, the thesis has demonstrated the significance of rel ative principle in map recognition from the perspective of geographical spatial relationship, i ncluding direction and measurement.2) The thesis has proposed an approach to validate the maintenance of relative principle in the schematic network maps. Then the thesis took 5 tube networks from London and etc. as examples, and validated their maintenance of the relative relation from the view of global and the local. The results shown that among the 5 tube networks, the maintenance rate of the principle of relativity in position are all over 80%, and 70% for the principle of relativity in length. So conclusions can be drawn that the schematic network maps which released by the government followed the relative principle3) Based on the version released by government, the thesis has redrawn the schematic network maps of those 5 cities’ tube networks, following the 4 principles accordingly: globally maintaining the relative relationship, locally maintaining the relative relationship, maintaining the relationship of position only and length only. The thesis then compared the geometry deformation between the redrawn schematic network maps and those released by government, evaluated their difference in map recognition through questionnaires.4) To find out how those different schematic network maps influence the users in path-choosing, the eye-tracking experiment is conducted on three versions of the maps, e.g. the one released by the government, the one globally maintaining the relative relationship and the one locally maintaining the relative relationship. Results shown that those schematic network maps followed the relative principle are better, in the way that they enable users to choose a path that is more convenient or less time-consuming.Taken together, conclusions can be drawn that the relative principle is benefit for map recognition, and should be included in the algorithms of automatically generation of schematic network maps.