基于对象方位的连续方向查询的优化技术

The Optimization Technology of Continuous Direction Query

连续方向查询中的结果是包含有效时域的,传统的拓扑运算无法计算出连续方向查询结果的有效时域。连续方向查询的传统处理方法是当结果发生变化时,重复执行方向查询,这种频繁的查询导致系统的消耗的增加。基于这种情况,本文提出了扩展的开放区域和相对坐标系的算法,就是先用扩展的开放区域计算出方向查询的结果,进行平移旋转,转化为相对坐标系内的坐标。这样可以迅速的计算出连续方向查询结果的有效时域。最后,在实验中比较了重复方向查询算法和扩展的开放区域算法的相对性能,实验结果表明扩展的开放区域算法的性能优于重复方向查询算法的性能。

The results of continuous direction query include time-domain. The topology operation＇s is which betweens open shapes and closed geometry objects couldn＇t compute out the time-domain. In this paper,we proposed that extended open-shapes strategy and Translate-Rotate strategy. Using extended open-shapes strategy, according to the results which satisfy query condition, and translate rotating it in the relative coordinates system. Ultimately, we computed the validity time interval of result set. Finally, this strategy could rapidly implement the continuous query of moving object. The experiment demonstrated that the extended open-shape strategy can outperform the strategy of repeating direction query in I/O cost：