One Click Focusing: An SQL-based Fast Loop Road Extraction Method for Mobile Map Services

摘要

This paper proposes a method for the fast loop roads extraction for mobile Web map services and applications. Since the existing loop road extraction method has drawbacks such as those related to the processing speed and interactivity, it has been difficult to apply the method to real-time applications such as mobile Web map services directly. Therefore, this paper proposes a fast extraction method that involves acquiring information on all loop roads with high efficiency in advance and storing the information in a database and querying those with SQL statements. The proposed method is 51.0 times faster than the previous method, and for expanded loop road extraction, it is 16.4-25.3 times faster than the previous method. Further, when used to build a loop road database, the proposed method, which involves the use of a tabulation method, is 3.86 times faster than the conventional method. We have developed the Web API function in order to acquire loop roads easily from other Web services. For the application of the proposed method, we have developed the One Click Focusing function that can modify the size, position, and scale of the focus automatically in fisheye-view maps.