Abstract
This paper proposes a new spatial data query, the continuous nearest neighbor query with the direction constraint (DCNN query). The DCNN query finds the nearest point of interest (POI), which also satisfies the direction constraint. The direction constraint depends on the direction of the user's speed. It is an angle range with the direction of the user's speed as the angle bisector. And the angle range is determined by the user. We study the snapshot and the continuous DCNN queries. The snapshot query finds the nearest POI according to the user's current location. The continuous query updates the results when the user is moving on a segment. To answer the DCNN queries, we propose R-tree-based approaches. The snapshot query algorithm is more efficient than the existing method. The continuous query algorithm finds the change points of the results according to two geographical properties. The experimental results show that we can answer the snapshot and the continuous queries accurately and efficiently.