测绘英语unit31

Notes to the Text
Unit 31 Image Processing and Analysis
Notes to the Text
2.In the above unenhanced image, a bluish tint can be seen all-over the image, producing a hazy appearance. This hazy appearance is due to scattering of sunlight by atmosphere into the field of view of the sensor. This effect also degrades the contrast between different landcovers.
Unit 31 Image Processing and Analysis
New words and Expressions cluster [kt] n. 群；簇；丛；串 theme [i:] n. 主题；主旋律；题目 plausible [:] adj. 貌似可信的，花言巧语的；貌似真实的， 似合理的 closed [kud] adj. 关着的；不公开的；封闭的 canopy [kni] n. 天篷；华盖；遮篷；苍穹 rayleigh scattering： 瑞利散射
map： 映射 interpolate [int:uit] v. 内插，插补 discriminate [int:uit] v. 区别，区分 shrub [ʃ] n. 灌木，灌木丛 turbid [t:id] a. 混浊的，脏的，不纯的 versus [:] prep. 与……相对 standard deviation： 标准差
Unit 31 Image Processing and Analysis
This image is displayed without any further enhancement
Unit 31 Image Processing and Analysis
Multispectral SPOT image after enhancement by a simple linear greylevel stretching
Unit 31 Image Processing and Analysis
Unit 31 Image Processing and Analysis
New words and Expressions extract [ik'strækt] v. 提取 prior to： 在前，居先 raw data： 原始数据；原始资料 deliver to： 交付；传达；转交 uneven [,ʌn'i:vən] a. 不均匀的 oblique [ə'bli:k, ə'blaik] a. 倾斜的 imaging conditions： 成像条件 conform to： 符合；遵照 image enhancement： 图象增强，影像增强 spatial filter： 空间滤波器；空间频率滤波器 enhancement [in'ha:nsmənt] n. 增强 bluish ['blu:iʃ] a. 带蓝色的
译文:上面没有增强的影像中，整个影像上可以看到浅蓝色调， 产生了朦雾。该朦雾是由于大气散射的太阳光进入到了传感器 的视场中。这个影响也降低了不同土地覆盖间的反差。
Unit 31 Image Processing and Analysis
Notes to the Text
3.The image can be enhanced by a simple linear grey-level stretching. In this method, a level threshold value is chosen so that all pixel values below this threshold are mapped to zero. An upper threshold value is also chosen so that all pixel values above this threshold are mapped to 255. All other pixel values are linearly interpolated to lie between 0 and 255. 译文:影像可以通过简单的线性灰度级拉伸来增强。在这个 方法中，选择一个下阈值使所有在这个阈值之下的像素值映射 为零。也选择一个上阈值使所有在这个阈值之上的像素映射为 255。所有其它的像素值线性地内插在0到255之间。
Notes to the Text
Unit 31 Image Processing and Analysis
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Unit 31 Image Processing and Analysis
1.Prior to data analysis, initial processing on the raw data is usually carried out to correct for any distortion due to the characteristics of the imaging system and imaging conditions. Depending on the user's requirement, some standard correction procedures may be carried out by the ground station operators before the data is delivered to the end-user. These procedures include radiometric correction to correct for uneven sensor response over the whole image and geometric correction to correct for geometric distortion due to Earth's rotation and other imaging conditions (such as oblique viewing). The image may also be transformed to conform to a specific map projection system. 译文:数据分析前，对原始数据通常进行初处理，以改正由 于成像系统的特性和成像条件产生的任何变形。根据用户要求， 在将数据交付终端用户之前可能由地面站操作员进行一些标准 改正程序。这些程序包括辐射修正以改正整个影像的不均匀的 传感器响应以及几何修正以改正由于地球的旋转和其它成像条 件( 如斜视)产生的几何变形。影像也可能被转换以符合特定的 ng and Analysis
New words and Expressions tint [tint] n. 色彩 hazy appearance： 朦雾 histogram [it] n. 直方图 available [i] adj. 有效的，可得的；可利用的；空闲的 shift [it] n. 移动；变化；手段；轮班；vi. 移动；转变；转换；vt. 转 移；改变；替换 gain factor： 增益系数，增益因子 anticipate [ntiiit] vt. 预期，期望；占先，抢先；提前使用 threshold value： 阈值；门限值；界限值 discriminate [dikiinit, dikiint] vt. 区别； 辨别 supervised [ju:id] v. 监督（supervise的过去式和过去分 词）；指导 unsupervised [,nju:id] adj. 无人监督的；无监督的 belong to： 属于
Unit 31 Image Processing and Analysis
4.In supervised classification, the spectral features of some areas of known landcover types are extracted from the image. These areas are known as the "training areas". Every pixel in the whole image is then classified as belonging to one of the classes depending on how close its spectral features are to the spectral features of the training areas. In unsupervised classification, the computer program automatically groups the pixels in the image into separate clusters, depending on their spectral features. Each cluster will then be assigned a landcover type by the analyst. 译文:在监督分类中，一些已知的土地覆盖类型区域的光谱特 征从影像中提取出来。这些区域就被称为是“训练区”。然后 将整个影像中的每个像素分类为其中一个类，依据它的光谱特 征与训练区光谱特征的接近程度。 在非监督分类中，计算机程序自动地把影像中的像素依据其 光谱特征分成几个组。然后由分析员给每个组分配一个土地覆 盖类。