共查询到18条相似文献,搜索用时 62 毫秒
1.
地表反照率是影响地表能量收支平衡的决定性参数之一,精确反演地表反照率需要考虑地表各向异性反射特征。本文尝试以双向反射分布函数BRDF原型为地表各向异性反射的先验知识,通过单方向反射率反演地表反照率。首先根据地面实测及MODIS多角度反射率数据对反演方法进行分析和精度评价,然后借助MODIS BRDF产品统计出研究区的主导BRDF原型,并联合环境一号卫星(HJ-1)单方向反射率数据反演30 m地表反照率,最终将结果与地表实测数据进行比较。结果表明:BRDF原型对BRDF的变化进行了约束,且能够适用于几十米尺度的遥感数据反照率的反演;不同级别的各向异性反射特征的分布是不均一的,借助于主导BRDF原型能够使大部分样本的地表反照率满足精度要求;利用研究区MODIS BRDF产品统计得到的主导BRDF原型为先验知识,通过HJ-1数据反演得到的地表反照率与地表实测反照率有较高的一致性,而朗伯假定条件下的反照率高于实测结果。本文算法简单高效,可为产生全国范围的中高分辨卫星反照率产品提供有价值的算法参考。 相似文献
2.
核驱动的Ross Thick-LiSparse Reciprocal(RTLSR)双向反射函数(BRDF)模型已广泛地应用于MODIS等星载传感器的业务化产品处理中。但是,对于多年MODIS二向反射产品历史数据,如何基于RTMLSR模型发展一种简单有效快速的方法,进行热点效应的校正是一个迫切需要解决的问题。本文提出了一种简单有效的方法,不需要对观测数据重新反演,直接在现有MODIS二向反射产品的基础上进行热点校正,方便用户对历史MODIS二向反射产品的使用。该方法应用POLDER-3/BRDF数据库和部分经MODIS业务化算法筛选的反射率数据进行验证,并与RTLSR模型和RTMLSR模型的结果进行比较,结果表明:(1)该方法比现有的MODIS业务化RTLSR算法,对热点反射率有明显改善,拟合相对误差平均降低了10.12%;(2)该方法相对于RTMLSR模型在热点反射率拟合效果上差别不大,相对误差相差2.10%;(3)该方法对热点和冷点归一化的植被指数(NDHD)的估算效果有一定程度的改善,相对于RTLSR模型降低了约4.99%,与RTMLSR模型的相对误差相差1.32%,该方法对直接应用现有MODIS BRDF产品,基于热点方向反射率反演植被结构参数(如植被聚集指数)的精度提高有现实应用价值。 相似文献
3.
该文系统地研究了BRDF反演和大气纠正的关系。研究中用到了MODIS的大气纠正法,而且,对于不同的植被类型和气溶胶光学深度用到了MODIS和MISR的角度采样。结果显示在大气纠正中考虑BRDF表面各向异性是必要的,而且表面BRDF的反演和大气纠正可以迭代进行,大量模拟证明这一迭代收敛迅速。 相似文献
4.
5.
6.
7.
8.
9.
多角度观测系统用于地面遥感实验中测量地物的双向反射特性。配合高光谱分辨率遥感卫星影像,可以反演得到地物的三维结构信息。多角度观测系统的几何精度直接影响到观测地物的范围及采集数据的准确性。对其进行评估,不仅为实验人员选择实验设备提供精度参数,而且有助于实验人员确定观测范围。以激光脚点最小包络圆半径作为评估参数,提供了一种评估多角度观测系统几何精度的方法;对自主研发的多角度观测系统的几何精度进行了计算与评估。对不同光谱仪视场下的理论观测范围与考虑系统几何精度后的实际观测范围进行了计算,并给出了参考。 相似文献
10.
11.
12.
13.
14.
15.
Unmanned Aerial Vehicles (UAVs) could flexibly and efficiently observe land surface and obtain surface information at very high frequency and resolutions. In recent years, UAV technology has been greatly improved and the UAVs are increasingly applied in large amount of civilian fields. The UAV Remote Sensing (UAVRS) is a comprehensive technology composed of UAV flying aircraft, light remote sensing payload, satellite positioning device, remote-control system, communication technology and application technology. An UAVRS system is mainly composed of UAV platform, load system, ground control and data transmission system and image processing system. With the popularity of civilian UAV products and the development of UAV remote sensing payload, UAVRS also shows an explosive growth trend in various industries. However, the short battery life and limited coverage of the civilian drones are one of the key factors restricting the UAVRS applications. Besides, although the application of UAVs in various industries and fields continues to deepen, most of them are single-type applications in a certain discipline or industry. The 5G technology and wireless communication technology advance and will give rise to the UAVRS applications in terms of“networking”,“IoT”, and“real-time”, as well as cross-domain and convergence application. The modern cities are highly complex and sociotechnical. They comprise people and communities interacting with one another and with objects (e. g., roads, buildings) within a range of urban settings or contexts. It is extremely difficult to monitor and manage such complex sociotechnical systems. The monitoring and mapping of pollutions, traffic, infrastructures are great challenges in rapidly changing cities, and especially gained increasing attentions of citizens and are putting great stresses on policy makers and urban planners. Theoretical and practical efforts to create better city monitoring and management systems have a long history. In the 21st century, we recognize and conceive “creative”,“smart”and“knowledge”cities, in which the multidisciplinary Information and Information and Communication Technology (ICT) has played a vital role. The Internet of Things (IoT) promotes the development of the smart cities. However, in various urban domains, the cities equipped with a sensor-based web, or a cyber-physical information infrastructure, are far from sufficient to help policy makers or citizens to get a full understanding of the real time or near real time city conditions. To this end, due to their mobility, autonomous operation, and communication/processing capabilities, UAVs are envisaged in many smart city application domains. In this article, we describe a technology of air-ground collaborative low-altitude UAV remote sensing network system. The system composes of intelligent UAV, the UAV base station (drone-in box) and operation system. The UAV remote sensing network can provide high-frequency and real-time observations of the land surface. Based on the UAV remote sensing network, we constructed a comprehensive application for urban governance. An UAVRS network composed of eight UAV base stations was deployed in Danzao Town, Foshan City. Connected through 5G network, the UAVRS network advances the UAV inspection frequency, spatial coverage, and response time. It provides revolutionary and intelligent services for local agents and departments of water affairs, environment protection, public security, urban management, and emergency. The UAVRS network system in Danzao is expected to develop a real-world smart city paradigm that could be copied and migrated to other towns across the country. © 2023 Science Press. All rights reserved. 相似文献
16.
17.
无人机影像匹配过程中,粗差是不可避免的,因此,获取稳健性较高的特征点进行无人机影像匹配至关重要。传统的方法是采用经典的RANSAC算法进行粗差剔除,该算法受抽样次数、误差阈值的影响,还会残存部分误匹配的特征点。利用图论原理,对SIFT算法提取的特征点进行预处理,通过构建特征点的能量函数剔除能量较低的特征点,可以提高匹配特征点的稳健性,减少特征点的粗差。本文提出了一种新的方法,将图论算法与经典的RANSAC算法相结合进行粗差剔除。该方法命名为GSIFT-RANSAC算法,利用该算法可以提高特征点的稳健性,获取高精度的单应矩阵。采用两组无人机影像进行验证,本文提出的算法与单独利用图论剔除特征点的算法相比,粗差剔除率分别提高了5.31%和14.29%,说明该方法效果较好。 相似文献
18.
仿地飞行对于无人机航测至关重要,能否相对地面保持稳定的航高直接关系到无人机在复杂地形区域的安全性和数据质量问题。本文提出一种基于单目视觉的无人机航高估计方法,通过光流法对无人机实时获取的视频进行跟踪和分析,提取运动信息以估算实时航高。试验结果表明,该方法能够快速、准确地估算无人机实时航高,在没有地表高程信息的情况下实现了自动仿地飞行。 相似文献