Lesson 21 Remote Sensing
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Remote sensing is the process of collecting data about objects or landscape features without coming into direct physical contact with them. Most remote sensing is performed from aircraft or satellites using instruments, which measure electromagnetic radiation (EMR) that is reflected or emitted from the terrain(as shown in Fig.21-1). In other words, remote sensing is the detection and measurement of electromagnetic energy emanating from distant objects made of various materials. This is done so that we can identify and categorize these objects by class or type, substance, and spatial distribution.
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1. Write T(True) or F(False) beside the following statements about the text. a. Passive systems beam artificially produced energy to a target and record the reflected component. b. Active systems detect only energy emanating naturally from an object, such as reflected sunlight or thermal infrared emissions. c. "Image-oriented" capitalizes on the pictorial aspects of the data and utilizes analysis methods which rely heavily on the generation of an image. d. "Numerical-oriented" results directly from the development of the computer and because it emphasizes the quantitative aspects of the data, treating the data abstractly as a collection of measurement. e. Using passive sensor systems—the system sends out electro-magnetic radiation towards target object (s) and measures the intensity of the return signal.
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3.These techniques are diverse, ranging from traditional methods of visual interpretation to methods using sophisticated computer processing. 译文：这些技术是多种多样的，从传统的视觉判断的方法到复杂的计算机处理。因此，遥感的两个主要组成部分就 是数据采集和数据分析。 4.The branch first mentioned above we refer to as "image-oriented" because it capitalizes on the pictorial aspects of the data and utilizes analysis methods which rely heavily on the generation of an image. 译文：我们把前面首先提到的分支技术称为图像遥感，因为它利用图像方面的数据，采用很大程度上依赖于图像的 生成的分析方法。
Remote sensing devices can be differentiated in terms of whether they are active or passive. Active systems, such as radar and sonar, beam artificially produced energy to a target and record the reflected component. Passive systems, including the photographic camera, detect only energy emanating naturally from an object, such as reflected sunlight or thermal infrared emissions. Today, remote sensors, excluding sonar devices, are typically
captured and recorded by remote sensing systems must be analyzed by interpretive and measurement techniques in order to provide useful information about the subjects of investigation. These techniques are diverse, ranging from traditional methods of visual interpretation to methods using sophisticated computer processing. Accordingly, the two major components of remote sensing are data capture and data analysis.
（范围）从……到…… 被称为 发出，放射 空间分布 地球轨道卫星 图像遥感 产生于……，由……引起 一排，一群，一批 发送；发出
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1.Most remote sensing is performed from aircraft or satellites using instruments, which measure electromagnetic radiation (EMR) that is reflected or emitted from the terrain. 译文：大多数遥感通过飞机或卫星完成，在这个过程中，使用仪器对从地面发射或反射电磁辐射（EMR）。 EMR ：electromagnetic radiation 电磁辐射 2.Active systems, such as radar and sonar, beam artificially produced energy to a target and record the reflected component. Passive systems, including the photographic camera, detect only energy emanating naturally from an object, such as reflected sunlight or thermal infrared emissions. 译文：有源系统，如雷达和声纳，对目标发射人为产生能量，然后记录反射的分量。无源系统，包括照相机，只检 测由对象自然反射的能量，如反射的太阳光或热红外辐射。 active systems:有源系统、主动系统 passive systems:无源系统、被动系统
Today we are acquiring earth observational data from earth-orbiting satellites, because of the wide view possible from satellite altitudes, the speed with which the satellite borne sensors travel, and the number of spectral bands used, very large quantities of data are being produced.
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range from…to… refer to as emanate from spatial distribution earth-orbiting satellites image-oriented result from an array of send out