Matching features such as curve segments in stereo images play a very important role in scene recomtruction. In this paper, a stereo matching algorithm for the trajectories composed of time stamped points is proposed....Matching features such as curve segments in stereo images play a very important role in scene recomtruction. In this paper, a stereo matching algorithm for the trajectories composed of time stamped points is proposed. Based on time stamped points, planar curve match measurements are given first, such as time constraint, cross-ratio invariant constraint and eplpolar geometry constraint; then, a trajectory matching method is proposed based on epipolar geometry constraint and cross-ratio invariant constraint. In order to match the planar curve segments projected by perspective projection system, the curve start time and end time are selected first to prepare match candidates. Then, the epipolar equation is used to discard the unmatched curve segment candidates. At last, a cross ratio invariant constxaint is used to find the most matched curve segments. If their match measurement is higher than the specialized threshold, a candidate with the least cross ratio difference is then selected as the match result; otherwise, no match is found. Unlike the conventional planar curve segments matching algorithm, this paper presents a weakly calibrated binocular stereo vision system which is based on wide baseline. The stamped points are obtained by targets detecting method of flying objects from image sequences. Due to wide baseline, there must exist the projection not in epipolar monotonic order or the curve segments located in very short distance and keeping the epipolar monotonic order. By using the method mentioned above, experiments are made to match planar curve segments not only in epipolar monotonic order but also not in epipolar monotonic order. The results show that the performance of our curve matching algorithm is effective for matching the arc-like planar trajectories composed of time stamped points.展开更多
时序分析是合成孔径雷达干涉测量(InSAR)的一项关键技术,它被广泛应用于监测广阔地区的地表缓慢形变。这种方法能够提供大范围、大面积的形变监测。其中,StaMPS PS方法凭借适用范围广、开源等优点,受到众多学者的使用。但在时序InSAR中...时序分析是合成孔径雷达干涉测量(InSAR)的一项关键技术,它被广泛应用于监测广阔地区的地表缓慢形变。这种方法能够提供大范围、大面积的形变监测。其中,StaMPS PS方法凭借适用范围广、开源等优点,受到众多学者的使用。但在时序InSAR中,对流层延迟相位会导致形变监测精度的降低,因此,以合肥市为研究区域,分析了经验模型线性改正、GACOS(generic atmospheric correction online service for InSAR)改正和欧洲中期天气预报中心(ECMWF)最新发布的ERA5数据集改正,并对比这3种方法在时序InSAR反演形变速率中的改正效果。通过计算得到研究区的标准差,进行比较分析和验证。其中线性改正、ERA5和GACOS改正后的标准差分别降低了21.71%、16.14%、10.38%。对于合肥区域,这3种方法均可减弱对流层延迟的影响,且精度都有所提高,其中线性改正效果最好,适用性更高,ERA5和GACOS受天气以及地面监测点密度等影响,在该区域改正效果较差。展开更多
To design an efficient protocol for sharing the encrypted lock keys in the renting house system,we introduce a new notion called time-and identitybased proxy reencryption(TIPRE)and the blockchain platform.Our CPA secu...To design an efficient protocol for sharing the encrypted lock keys in the renting house system,we introduce a new notion called time-and identitybased proxy reencryption(TIPRE)and the blockchain platform.Our CPA secure TIPRE scheme is constructed from Green et al.’s identity-based proxy reencryption scheme by adding the time property.In every time period,a time stamp authority generates a public key embedded with the current time stamp for each user.In our protocol for the renting house system,the TIPRE scheme is the primary building block,and the blockchain platform serves instead of a trusted third party,such as a real estate agency between landlords and tenants.The TIPRE scheme allows the landlord to change the lock key at each time period for safety.The blockchain platform allows the landlords and tenants to directly interact,and all of the interactions are recorded in the blockchain database to provide the desired security requirements,such as nonrepudiation and unforgeability.Finally,we provide the secure analysis of our protocol and test its performance by implementing it in the MacBook Pro and the Intel Edison development platforms.展开更多
基金The National Natural Science Founda-tion of China (No.60135020) and the National Defence Key Pre-research Project of China (No.413010701-3)
文摘Matching features such as curve segments in stereo images play a very important role in scene recomtruction. In this paper, a stereo matching algorithm for the trajectories composed of time stamped points is proposed. Based on time stamped points, planar curve match measurements are given first, such as time constraint, cross-ratio invariant constraint and eplpolar geometry constraint; then, a trajectory matching method is proposed based on epipolar geometry constraint and cross-ratio invariant constraint. In order to match the planar curve segments projected by perspective projection system, the curve start time and end time are selected first to prepare match candidates. Then, the epipolar equation is used to discard the unmatched curve segment candidates. At last, a cross ratio invariant constxaint is used to find the most matched curve segments. If their match measurement is higher than the specialized threshold, a candidate with the least cross ratio difference is then selected as the match result; otherwise, no match is found. Unlike the conventional planar curve segments matching algorithm, this paper presents a weakly calibrated binocular stereo vision system which is based on wide baseline. The stamped points are obtained by targets detecting method of flying objects from image sequences. Due to wide baseline, there must exist the projection not in epipolar monotonic order or the curve segments located in very short distance and keeping the epipolar monotonic order. By using the method mentioned above, experiments are made to match planar curve segments not only in epipolar monotonic order but also not in epipolar monotonic order. The results show that the performance of our curve matching algorithm is effective for matching the arc-like planar trajectories composed of time stamped points.
文摘时序分析是合成孔径雷达干涉测量(InSAR)的一项关键技术,它被广泛应用于监测广阔地区的地表缓慢形变。这种方法能够提供大范围、大面积的形变监测。其中,StaMPS PS方法凭借适用范围广、开源等优点,受到众多学者的使用。但在时序InSAR中,对流层延迟相位会导致形变监测精度的降低,因此,以合肥市为研究区域,分析了经验模型线性改正、GACOS(generic atmospheric correction online service for InSAR)改正和欧洲中期天气预报中心(ECMWF)最新发布的ERA5数据集改正,并对比这3种方法在时序InSAR反演形变速率中的改正效果。通过计算得到研究区的标准差,进行比较分析和验证。其中线性改正、ERA5和GACOS改正后的标准差分别降低了21.71%、16.14%、10.38%。对于合肥区域,这3种方法均可减弱对流层延迟的影响,且精度都有所提高,其中线性改正效果最好,适用性更高,ERA5和GACOS受天气以及地面监测点密度等影响,在该区域改正效果较差。
基金This research is partially supported by the National Natural Science Foundation of China under Grant Nos.61672016the Jiangsu Qing Lan Project,the Six Talent Peaks Project in Jiangsu Province under Grant RJFW-010the Guangxi Key Laboratory of Cryptography and Information Security under Grant GCIS201815.
文摘To design an efficient protocol for sharing the encrypted lock keys in the renting house system,we introduce a new notion called time-and identitybased proxy reencryption(TIPRE)and the blockchain platform.Our CPA secure TIPRE scheme is constructed from Green et al.’s identity-based proxy reencryption scheme by adding the time property.In every time period,a time stamp authority generates a public key embedded with the current time stamp for each user.In our protocol for the renting house system,the TIPRE scheme is the primary building block,and the blockchain platform serves instead of a trusted third party,such as a real estate agency between landlords and tenants.The TIPRE scheme allows the landlord to change the lock key at each time period for safety.The blockchain platform allows the landlords and tenants to directly interact,and all of the interactions are recorded in the blockchain database to provide the desired security requirements,such as nonrepudiation and unforgeability.Finally,we provide the secure analysis of our protocol and test its performance by implementing it in the MacBook Pro and the Intel Edison development platforms.
