Photogrammetry is experiencing an era of democratization mostly due to the popularity and availability of many commercial off-the-shelf devices,such as drones and smartphones.They are used as the most convenient and e...Photogrammetry is experiencing an era of democratization mostly due to the popularity and availability of many commercial off-the-shelf devices,such as drones and smartphones.They are used as the most convenient and effective tools for high-resolution image acquisition for a wide range of applications in science,engineering,management,and cultural heritage.However,the quality,particularly the geometric accuracy,of the outcomes from such consumer sensors is still unclear.Furthermore,the expected quality under different control schemes has yet to be thoroughly investigated.This paper intends to answer those questions with a comprehensive comparative evaluation.Photogrammetry,in particular,structure from motion,has been used to reconstruct a 3D building model from smartphone and consumer drone images,as well as from professional drone images,all under various ground control schemes.Results from this study show that the positioning accuracy of smartphone images under direct geo-referencing is 165.4 cm,however,this could be improved to 43.3 cm and 14.5 cm when introducing aerial lidar data and total station surveys as ground control,respectively.Similar results are found for consumer drone images as well.For comparison,this study shows the use of the professional drone is able to achieve a positioning accuracy of 3.7 cm.Furthermore,we demonstrate that through the combined use of drone and smartphone images we are able to obtain full coverage of the entire target with a 2.3 cm positioning accuracy.Our study concludes that smartphone images can achieve an accuracy equivalent to consumer drone images and can be used as the primary data source for building facade data collection.展开更多
针对类美国末段高空域防御(Terminal High Altitude Area Defense,THAAD)系统的红外导引头外形,开展了气动光学效应计算分析,并将其用于飞行器设计。利用国家数值风洞工程高速流场计算软件NNW-HyFLOW,考虑热化学非平衡效应和材料传热耦...针对类美国末段高空域防御(Terminal High Altitude Area Defense,THAAD)系统的红外导引头外形,开展了气动光学效应计算分析,并将其用于飞行器设计。利用国家数值风洞工程高速流场计算软件NNW-HyFLOW,考虑热化学非平衡效应和材料传热耦合效应,对导引头典型状态的流场进行了模拟,获得了流场的密度、温度、压力等参数和窗口的温度场参数。基于流场参数,利用HyFLOW气动光学传输效应计算功能,开展了红外光学传输成像计算;利用HyFLOW气动光学辐射效应计算模块,开展了流场和光学窗口的热辐射计算。计算结果表明,类THAAD导引头在30 km以上飞行时,流场和光学窗口基本不会影响目标信号的光学传输成像,但流场和窗口的热辐射效应会对导引头识别目标造成影响。不过随着飞行高度的升高,这种影响会减小。展开更多
文摘Photogrammetry is experiencing an era of democratization mostly due to the popularity and availability of many commercial off-the-shelf devices,such as drones and smartphones.They are used as the most convenient and effective tools for high-resolution image acquisition for a wide range of applications in science,engineering,management,and cultural heritage.However,the quality,particularly the geometric accuracy,of the outcomes from such consumer sensors is still unclear.Furthermore,the expected quality under different control schemes has yet to be thoroughly investigated.This paper intends to answer those questions with a comprehensive comparative evaluation.Photogrammetry,in particular,structure from motion,has been used to reconstruct a 3D building model from smartphone and consumer drone images,as well as from professional drone images,all under various ground control schemes.Results from this study show that the positioning accuracy of smartphone images under direct geo-referencing is 165.4 cm,however,this could be improved to 43.3 cm and 14.5 cm when introducing aerial lidar data and total station surveys as ground control,respectively.Similar results are found for consumer drone images as well.For comparison,this study shows the use of the professional drone is able to achieve a positioning accuracy of 3.7 cm.Furthermore,we demonstrate that through the combined use of drone and smartphone images we are able to obtain full coverage of the entire target with a 2.3 cm positioning accuracy.Our study concludes that smartphone images can achieve an accuracy equivalent to consumer drone images and can be used as the primary data source for building facade data collection.
文摘针对类美国末段高空域防御(Terminal High Altitude Area Defense,THAAD)系统的红外导引头外形,开展了气动光学效应计算分析,并将其用于飞行器设计。利用国家数值风洞工程高速流场计算软件NNW-HyFLOW,考虑热化学非平衡效应和材料传热耦合效应,对导引头典型状态的流场进行了模拟,获得了流场的密度、温度、压力等参数和窗口的温度场参数。基于流场参数,利用HyFLOW气动光学传输效应计算功能,开展了红外光学传输成像计算;利用HyFLOW气动光学辐射效应计算模块,开展了流场和光学窗口的热辐射计算。计算结果表明,类THAAD导引头在30 km以上飞行时,流场和光学窗口基本不会影响目标信号的光学传输成像,但流场和窗口的热辐射效应会对导引头识别目标造成影响。不过随着飞行高度的升高,这种影响会减小。
