共查询到20条相似文献,搜索用时 15 毫秒
1.
Herbert J. Kramer 《International journal of remote sensing》2013,34(15):4285-4337
This article gives a global overview of some aspects of small satellite developments since the launch of Sputnik‐1 50 years ago. These developments are offering new opportunities for remote sensing. The earliest satellites were small but, as time went on, the satellites that were flown were developed to serve several different projects and they became larger and more expensive and took a long time to design, build and be launched. One of the extreme examples was Envisat. For these large satellites compromises often had to be made between different objectives and different instruments. A failure of the whole system meant the death of many different projects. The future is likely to see more small satellites, each of which is dedicated to a particular mission objective and carries a single instrument. Through this approach more and more countries around the world are becoming involved in Earth observation from space, not just in using the data from the major established systems but also in constructing their own systems. There were some small, low‐cost satellites in the early days, but they were overlooked or considered toys by the space community. The first microsatellites were built by enthusiasts of the amateur radio community and launched in the early 1960s. The invention/introduction of the microprocessor in the 1970s represented a quantum jump for the onboard capabilities of a spacecraft. This technology introduction represented a prime catalyst in the development of microsatellites since it enabled small physical structures in support of sophisticated data handling applications. The engineering of microsatellites, which emerged in the early 1980s, took a radical change of approach from the custom design of traditional spacecraft, namely a design‐to‐capability scheme to achieve cost reductions by focusing on available, and existing technologies using a general purpose bus and ‘off‐the‐shelf’ components and instruments. The new approach of small satellite design was pioneered by Surrey Satellite Technology Ltd (SSTL) of Surrey University, UK. SSTL's lead has now been followed by various companies and space agencies throughout the world. A key feature of this work is the development of microsatellite technology transfer programmes, providing partnerships and on‐the‐job training of engineers and scientists of foreign national organizations in cooperative programmes – in particular to those who were not in a position to start or afford their own space projects – to participate in the development of their own microsatellites. In addition to discussing these developments, this article also covers small satellite classification, small satellite initiatives in the USA, small satellite development in the rest of the world, some aspects of the technology and applications of small satellites, and small satellites developed by universities, particularly the CubeSats programme. Today, small satellites are changing the economics of space. These spacecraft embrace cutting edge Commercial Off‐The‐Shelf (COTS) technology, permitting novel and less‐expensive ways to perform meaningful observation missions, although there are various technical challenges. There are several synthetic aperture radar (SAR) and hyperspectral imaging missions on small satellites in operation and in planning. 相似文献
2.
Tom Beer 《Remote sensing of environment》1980,9(1):65-85
Microwave data from the ESMR sensor of the NIMBUS-6 satellite is used to obtain (i) rainfall rates during a tropical cyclone over the northern part of Western Australia, (ii) wind speed over the surface of the waters of the coastal regions of the southern part of Western Australia, and (iii) the microwave emissivity over the land surface of the southern part of Western Australia. 相似文献
3.
Ran Qiong Xu Xiaodong Zhao Shizhi Li Wei Du Qian 《Multimedia Tools and Applications》2020,79(13-14):8985-9001
Multimedia Tools and Applications - Remote sensing image data have been widely applied in many applications, such as agriculture, military, and land use. It is difficult to obtain remote sensing... 相似文献
4.
DAVID SHERES DAVIDSON T. CHEN G A SPAR R. VALENZUELA 《International journal of remote sensing》2013,34(11):1629-1640
Abstract First, a general review is presented of wave-current interaction processes ( for horizontal shears) and their effect on radar backscatter and radar imagery ( SAR/ RAR ) Then numerical results on the refraction of wave energy trajectories by complex bottom topography (finite depth) and a linear shear current are presented. For deep water, the wave-energy trajectories are given for mesoscale currents ( e.g. eddies and double-vortex configurations). The focusing of wave energy by variable currents found here should have important influence on the spatial scale of wind stress over the ocean, and on optical and acoustic properties of the upper layer of the ocean. 相似文献
5.
B.V Vinogradov 《Remote sensing of environment》1977,6(2):83-94
At the XIIth International Botanical Congress, on July 4, 1975, a new direction in scientific methodology was evaluated for the first time within the framework of an International Union of Biological Sciences—remote sensing of vegetation and the environment. Remote sensing is a method of studying the composition, structure, dynamics, and productivity of ecosystems and the state of the biosphere by means of reflectance and emittance characteristics of the earth's surface measureable from aircraft and spacecraft, and the interpretation of such remotely sensed imagery. Remote cartography is conducted with aerial and space images with a scale of from 1: 1000 to 1:30 000 000. Phytomass can be measured by comparing the dependence of the phytocenometric characteristics with the magnitude of the remotely obtained signal. Phenology and dynamics are revealed by means of optical comparison of successive images. Structural ecological investigations can be based on spatial and factoral integration of ecosystems on single, remotely-sensed images. Remote sensors record spatial and temporal variability of the reflective and emissive characteristics of vegetative ground cover. Anthropogeneous effects are recognized by indication of vegetation clearing, fires, ploughing, overgrazing, water and air pollution, and water and wind erosion. 相似文献
6.
Remote sensing of foliar chemistry 总被引:76,自引:0,他引:76
Paul J. Curran 《Remote sensing of environment》1989,30(3):271-278
Remotely sensed data are being used to estimate foliar chemical content as a result of our need for the information and our increasing ability to understand and measure foliar spectra. This paper reviews how stepwise multiple regression and deconvolution have been used to extract chemical information from foliar spectra, and concludes that both methods are useful, but neither is ideal. It is recommended that the focus of research be modeling in the long term and experimentation in the short term. Long-term research should increase our understanding of the interaction between radiation and foliar chemistry so that the focus of research can move from leaf model to canopy model to field experiment. Short-term research should aim to design experiments in which remotely sensed data are used to generate unambiguous and accurate estimates of foliar chemical content. 相似文献
7.
8.
Xiaohan Liao Yu Zhang Fenzhen Su Zhi Ding Jianli Liu 《International journal of remote sensing》2013,34(21):7138-7153
ABSTRACTMany users are now showing strong interest in UAV RS (Unmanned Aerial Vehicle Remote Sensing) due to its easy accessibility. UAVs have become popular platforms for remote sensing data acquisition. In a number of practical and time constrained circumstances, UAV RS data have been widely used as a substitute for traditional satellite remote sensing data. However, airspace-related regulations are far behind the rapid growth in the number of UAVs and their wide applications. Much effort of the network-based UAV RS have been made by the UAV RS group of the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (IGSNRR, CAS), which proposed the concept of UAV RS data carrier. UAV RS data carrier refers to UAV RS data platform with task planning, data storage, image processing, product generation and output products for various UAVs. An ongoing effort to create a nationwide UAV RS network in addition to an existing ground observational network is being carried out in China. 相似文献
9.
A point in the Letter by Curran (1983) on remote sensing terminology is expanded and a further point made. 相似文献
10.
Anitha Nair Shubha Sathyendranath Trevor Platt Jesus Morales Venetia Stuart Marie-Hélène Forget Emmanuel Devred Heather Bouman 《Remote sensing of environment》2008,112(8):3366-3375
The principal goal in early missions of satellite-borne visible spectral radiometry (ocean colour) was to create synoptic fields of phytoplankton biomass indexed as concentration of chlorophyll-a. In the context of climate change, a major application of the results has been in the modelling of primary production and the ocean carbon cycle. It is now recognised that a partition of the marine autotrophic pool into a suite of phytoplankton functional types, each type having a characteristic role in the biogeochemical cycle of the ocean, would increase our understanding of the role of phytoplankton in the global carbon cycle. At the same time, new methods have been emerging that use visible spectral radiometry to map some of the phytoplankton functional types. Here, we assess the state of the art, and suggest paths for future work. 相似文献
11.
Abstract The widespread misuse of the word ‘acronym’ is pointed out. 相似文献
12.
E. P. Green C. D. Clark P. J. Mumby A. J. Edwards A. C. Ellis 《International journal of remote sensing》2013,34(5):935-956
Different approaches to the classification of remotely sensed data of mangroves are reviewed, and five different methodologies identified. Landsat TM, SPOT XS and CASI data of mangroves from the Turks and Caicos Islands, were classified using each method. All classifications of SPOT XS data failed to discriminate satisfactorily between mangrove and non-mangrove vegetation. Classification accuracy of CASI data was higher than Landsat TM for all methods, and more mangrove classes could be discriminated. Merging Landsat TM and SPOT XP data improved visual interpretation of images, but did not enhance discrimination of different mangrove categories. The most accurate combination of sensor and image processing method for mapping the mangroves of the eastern Caribbean islands is identified. 相似文献
13.
14.
T. E. BEAUMONT 《International journal of remote sensing》2013,34(2):411-427
Abstract The commercialization of remote sensing has been initiated during a time of change in consulting engineering practice. As the engineering community constitutes a significant potential market for remote-sensing data and value-added products, current trends in the profession are reviewed against the initial impact of the commercialization of data available from Earth observation satellite systems. 相似文献
15.
城市遥感影像语义模型 总被引:2,自引:0,他引:2
在快速的城市化进程中,遥感技术可以为城市土地利用变化提供直观、准确、同步的资料.在应用城市遥感影像的过程中,根据城市的社会、经济及自然环境特征,按照城市用地类型的分类建立不同功能区的模型,最终结合起来,组成整个城市的遥感影像判读应用语义模型,使在目视判读中所积累的知识应用到计算机的自动判读过程中,以提高遥感技术在城市领域的应用精度与效率. 相似文献
16.
遥感图像纹理特征是光谱相近林型准确分类的有效方法,然而其带来分类特征向量维数增加和计算量增大。因此,对南方山区林地TM图像进行独立成分分析ICA降维,通过计算灰度共生矩阵获取纹理特征,使用SVM分类,研究林地类型的快速分类方法。结果表明,ICA与SVM法利用遥感图像纹理特征可较准确地实现林地类型分类,分类总精度、Kappa系数分别为85.4%、0.73,均高于SVM法、BP神经网络法、最大似然法、最小距离法;其对阔叶林、针叶林、竹林的分类精度依次为78.2%、80.1%、84.3%,误识率主要是由于混交林而造成两类林地之间存在交集,易出现的针阔混交林使得阔叶林、针叶林的分类精度低于竹林。 相似文献
17.
The role of UNESCO is to promote international peace and security through cooperation in the fields of education, science and culture. In view of eradicating illiteracy, overcoming unsustainability of natural resources, confronting environmental problems, safeguarding historical monuments, and preserving natural and cultural heritage, UNESCO develops international research programmes and makes best possible use of new advances in technology, namely remote sensing and GIS, in order to effectively carry out activities in the framework of its programmes. Part one describes remote sensing and GIS use in international programmes such as the Man and the Biosphere (MAB) programme for biosphere reserve development and ecosystem monitoring, management and conservation; the International Hydrological Programme (IHP) for surface and ground water research management; the International Geological Correlation Programme (IGCP) for the creation of a data base on the spectral signatures of rocks and soils; and in several projects concerning ocean investigation and climate observation conducted in the framework of the Intergovernmental Oceanographic Commission (IOC). In part two constraints of using the remote sensing and GIS technology are addressed and remaining difficulties in accessing and exchanging data, training issues and costs are discussed. 相似文献
18.
Daniel J. Jobson Richard G. Zingmark Stephen J. Katzberg 《Remote sensing of environment》1980,9(4):351-362
A remote sensing instrument was mounted on a 50-ft tower overlooking North Inlet Estuary, South Carolina in order to conduct a remote sensing study of benthic microalgae. The instrument was programmed to take multispectral imagery data along a 90° horizontal frame in six spectral bands ranging from 400–1050 nm and had a ground resolution of about 3 cm. Imagery measurements were encoded in digital form on magnetic tape and were stored, decoded, and manipulated by computer. Correlation coefficients were calculated on imagery data and chlorophyll α concentrations derived from ground truth data. The most significant correlation occurred in the blue spectral band with numerical values ranging from ?0.81 to ?0.88 for three separate sampling periods. Mean values of chlorophyll α for a larger section of mudflat were estimated using regression equations. The scanner has provided encouraging results and promises to be a useful tool in sampling the biomass of intertidal benthic microalgae. 相似文献
19.
PAUL J. CURRAN 《International journal of remote sensing》2013,34(9):1255-1275
Abstract Remote sensing is a technique used in scientific and technological approaches to geographical research. In the scientific approaches (of which the empirical are the most popular) the motivation is curiosity, the goal is knowledge and the methodology is often induction to derive theory and then deduction to verify theory. In the technological approaches the motivation is human need, the goal is the application of knowledge and the methodology is design. This review discusses both approaches, concentrating on the problems of taking a scientific approach and the unwillingness of geographers to accept an often more suitable technological approach. It is argued throughout that both types of approach can be valid, both can be useful and both are suitable methodologies for remote sensing in geography. 相似文献
20.
Remote sensing support for national forest inventories 总被引:1,自引:0,他引:1
National forest inventory programs are tasked to produce timely and accurate estimates for a wide range of forest resource variables for a variety of users and applications. Time, cost, and precision constraints cause these programs to seek technological innovations that contribute to measurement and estimation efficiencies and that facilitate the production and distribution of an increasing array of inventory data, estimates, and derived products. Many of the recent innovations have involved remotely sensed data and related statistical estimation techniques. Current applications of remote sensing in support of national forest inventories are reviewed for three areas: (1) observation or measurement, meaning using remotely sensed data in lieu of field observations or measurements; (2) estimation, meaning calculation of traditional inventory areal estimates such as forest area or volume per unit area; and (3) mapping. Future applications focus on two areas: augmenting field measurements with remotely sensed data obtained from lidar sensors and Internet accessible map-based estimation. 相似文献