Yap Florence G H, Yen Hong-Hsu
Center for General Education, Chang Gung University, Taoyuan 333, Taiwan.
Department of Information Management, Shih Hsin University, Taipei 116, Taiwan.
Sensors (Basel). 2016 Dec 30;17(1):64. doi: 10.3390/s17010064.
In this paper, we consider the visual sensor deployment algorithm in Pan-Tilt-Zoom (PTZ) Wireless Visual Sensor Networks (WVSNs). With PTZ capability, a sensor's visual coverage can be extended to reduce the number of visual sensors that need to be deployed. The coverage zone of a visual sensor in PTZ WVSN is composed of two regions, a Direct Coverage Region (DCR) and a PTZ Coverage Region (PTZCR). In the PTZCR, a visual sensor needs a mechanical pan-tilt-zoom operation to cover an object. This mechanical operation can take seconds, so the sensor might not be able to adjust the camera in time to capture the visual data. In this paper, for the first time, we study this PTZ time-aware PTZ WVSN deployment problem. We formulate this PTZ time-aware PTZ WVSN deployment problem as an optimization problem where the objective is to minimize the total visual sensor deployment cost so that each area is either covered in the DCR or in the PTZCR while considering the PTZ time constraint. The proposed Time Aware Coverage Zone (TACZ) model successfully captures the PTZ visual sensor coverage in terms of camera focal range, angle span zone coverage and camera PTZ time. Then a novel heuristic, called Time Aware Deployment with PTZ camera (TADPTZ) algorithm, is proposed to solve the problem. From our computational experiments, we found out that TACZ model outperforms the existing coverage model under all network scenarios. In addition, as compared to the optimal solutions, the TACZ model is scalable and adaptable to the different PTZ time requirements when deploying large PTZ WVSNs.
在本文中，我们考虑了在具有云台变焦（PTZ）功能的无线视觉传感器网络（WVSN）中的视觉传感器部署算法。借助PTZ功能，可以扩展传感器的视觉覆盖范围，从而减少需要部署的视觉传感器数量。PTZ WVSN中视觉传感器的覆盖区域由两个区域组成，即直接覆盖区域（DCR）和PTZ覆盖区域（PTZCR）。在PTZCR中，视觉传感器需要进行机械云台变焦操作来覆盖物体。这种机械操作可能需要几秒钟，因此传感器可能无法及时调整摄像头以捕获视觉数据。在本文中，我们首次研究了这个考虑PTZ时间的PTZ WVSN部署问题。我们将这个考虑PTZ时间的PTZ WVSN部署问题表述为一个优化问题，其目标是最小化视觉传感器的总部署成本，以便在考虑PTZ时间约束的情况下，每个区域要么在DCR中被覆盖，要么在PTZCR中被覆盖。所提出的时间感知覆盖区域（TACZ）模型成功地从相机焦距、角度跨度区域覆盖和相机PTZ时间方面捕捉了PTZ视觉传感器的覆盖情况。然后提出了一种新颖的启发式算法，即带PTZ相机的时间感知部署（TADPTZ）算法来解决该问题。从我们的计算实验中，我们发现TACZ模型在所有网络场景下都优于现有的覆盖模型。此外，与最优解相比，TACZ模型具有可扩展性，并且在部署大型PTZ WVSN时能够适应不同的PTZ时间要求。
