The Study of two-phase SRM for Surveillance of Massive Moving Objects on Mobile Devices

• Main Authors: Wen-Feng Chen, 陳文峰
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/fd2523

碩士 === 朝陽科技大學 === 資訊工程系碩士班 === 93 === Recently, the wireless network and personal digital assistant (PDA) is getting more and more popular. It causes that the wireless communication capability becomes a built-in function of PDA. Many mobile information systems are also implemented on PDA. However, the implementation is constrained by four primary resources: the storage, computing speed, screen size, and network bandwidth. It causes that some functions of systems need special designs to meet these constrains. On the other hand, the precision of global positioning system (GPS) is increased. It causes that many applications provide location-related services by integrating GPS and geographical information system (GIS), such as vehicle navigation or management. Many researches are also focused on the problems related to location-related services. When these services are intent to be implemented on PDA, a primitive function is the display of locations. If the size of locations is massive and continuous changed, the constraints on screen size and network bandwidth and computing speed become three primary problems. To overcome the above problems, a scale-based reduction method for massive locations is proposed in this paper. The SRM has two-phases. Zoom Phase is Map Reduction, it is mainly to reduce the network transmission. The origin map is split to a set of squares based on the selected scale. The size and area of squares for reduction is determined by the scale. Those locations in the same square are then reduced into a single value and thus reduce the network transmission. Mosaic Phase is Screen Reduction, it is mainly follow Zoom Phase to reduce the network transmission, display time and reduction. In this paper, the two-phase SRM Locations for reduction are generated based on random or group distributions. The simulation results on Zoom Phase reveal that the reduction ratio can achieve 82.4% and 94.6% under group and random distribution, respectively. The transmission ratio is varied from the scale. It can be lower to 1% for both distributions. On Mosaic Phase the simulation results reveal that the reduction ratio is 52.3% under group and random distribution. The transmission ratio is varied from the Screen Scale. It can be lower to 1% for both distributions. The result illustrates that the scale-based reduction method can overcome the screen size and network bandwidth constraints for displaying massive locations on PDA.