Creative Commons License

Creative Commons Attribution-Share Alike 4.0 License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.


Landmarks are yet to be integrated with mainstream mobile phone based navigation aids. In geographical regions where land marks are commonly used by the community for navigation support, the lack of them in electronic navigation aids make them less useful for such communities. In this study a land marks based navigation model is derived considering the value of them for local community in Sri Lanka. The landmarks can be prominent or not, make sense only during certain time of the day or been important differently for people with different age groups. We assume that the attributes of landmarks can be used to give a strength value for them for navigation. In this study three parameters, the visibility of them at different time of the day, the horizontal spread of the landmark and the height of them are considered as attributes which gives strength to a landmark. First, to give more importance to landmarks, we have developed an algorithm where not only the distance of a route but the strength of landmarks is also considered when selecting the best route to navigate. The Dijikstra algorithm is used as the base which output possible shortest paths considering only the distance. This algorithm was enhanced to output the optimum paths considering both the distance and the strength of landmarks along it. If the route is having more strength related to landmarks, it is prioritized. The route’s strength is defined based on number of landmarks visible along it and the strength of them. In order to calculate the number of landmarks along a route a landmark buffer is used. The day/night visibility and the height/spread are used to calculate the strength of the landmarks along the route. Second, to utilize the mobile screen in more effective manner which has the size limitation, map generalization approach is used when showing the navigation path. We have identified that after placing landmarks on a mobile screen, the map become too congested and it becomes difficult to read the navigation path. This is more prominent when the path is having many turns. The selected path is reduced to a linear map which shows the path reducing curves while emphasising the turns by markers. The linear map, which is a schematic representation of the actual map, reduces the path between junctions to straight lines. The junctions and turns are also incorporated to the resulting map. The landmarks around significant turns are also provided and guidance is provided based on landmarks. Douglas-Peucker algorithm is used to derive the linear path. A prototype implementation is done using mobile web approach to reduce the platform dependency. In the simple mobile web application developed, jQuery mobile, and php are used for the user interface development and server side implementations respectively. PostgreSQL with postGIS capabilities and pgRouting is used as a spatial database. Web services and smart queries are used to implement the basic functionalities communicating with the spatial database and the front end. The application is still being verified and tested in Sri Lanka at the moment.



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