Design of dynamic multi-scale maps for land vehicle navigation

Abstract

A main component of an Intelligent Transport System (ITS) is the navigation system to be used in the 'intelligent' car. In fact, driving a vehicle is a complex task as the driver has to control the vehicle as well as make decisions about getting to his destination. Too much information on the map (a complex map) would confuse the driver, while too little information would not be enough for the user to compare with the actual environment. Likewise, sufficient information poorly presented would also result in confusion. This paper reports on a study of the optimal cartographic design of a navigation map through an investigation of different designs with different content levels. Attention was focused on the use of dynamic variables where features in close proximity of the vehicle would be highlighted such that the prominence of map contents was not a constant in order to lower the map complexity. Users were provided with two modes of navigation, with or without the planned route. A function to calculate the restricted road area according to the time was developed and gained positive comment from users. The effectiveness of the design was investigated by using a map complexity test suggested by MacEachren in 1982. It was concluded that road segments were highlighted by changing the color; building names and road names were highlighted by changing the color and increasing the font size; and direction restriction symbols were highlighted by increasing in size plus flashing effect. Different prominences of map contents were presented. Perspective symbols were designed and direction restriction symbols were designed to replicate the road signs developed by the local Transport Department. Both of them gained appreciations from users. Also, a set of maps with different complexity was designed such that the users would be provided with different levels of contents and representation by zooming in and out. The results were then confirmed by a viewing time record. Finally the design of the map was investigated by a map evaluation process.