问题 问答题 简答题

简述遥感图像计算机分类的一般流程。

答案

参考答案:

遥感图像计算机分类处理的基本过程,包括原始图像的预处理、训练区的选择、特征选择和特征提取、分类、检验结果以及成果输出等。

(1)原始图像的预处理

原始图像的预处理(preprocessing)就是指对观测数据作成像处理,以及图像的几何校正、辐射校正、量化、采样、预滤波、去噪声等处理,以便获得一幅比较清晰、对比度强、位置准确的图像以提高分类精度。

(2)训练区的选择

从待处理数据中抽取具有普遍性、代表性的数据作为训练群本。训练区选择得准确与否,训练样本数是否足够,关系到分类精度的高低。在监督分类中,训练区选择的最好的办法是选择一、两个典型区域,各类地物全有,进行实地调查,调查时,对照实地将被分类的遥感影像,一一识别,在图上标好,再到计算机上将这些数据提出。如果受客观条件的限制,可以借助于地图、航片或其他专题资料进行选择等。在上述资料都没有的情况下也可以先做非监督分类,在分类结果中选择训练区。

(3)特征选择和特征提取

特征选择(featureselection)是从众多特征中挑选出可以参加分类运算的若干个特征。特征提取(featureextraction)是在特征选择之后,利用特征提取算法从原始特征中求出最能反映其类别特性的一组新特征,完成样本空间到特征空间的转换。通过特征提取既可以达到数据压缩的目的,又提高了不同类别特征之间的可区分性。

(4)图像分类运算

图像分类运算(classification)就是根据影像特点和分类目的设计或选择恰当的分类器及其判别准则,对特征矢量集进行划分,完成分类工作。

(5)检验结果

主要是对分类的精度与可靠性进行评价。进入传感器的遥感信息由于受传感器空间分辨率和光谱分辨率的限制,常常得到混合的信息。有时地物本身就是混合在一起的,例如植被覆盖下的土壤。因此不存在理想的分类器,加上“同物异谱”、“异物同谱”现象的存在,错分的情况普遍存在,因此,分类后都必须进行检验,错分像元所占的比例越小,则分类结果越佳。

(6)结果输出

包括分类结果图像的输出,以及分类结果的统计值,例如各类别的地物占地面积、类别集群的统计中心和方差等。

单项选择题

Anthropology is the study of human beings as creatures of society. It (1) its attention upon those. physical characteristics and industrial techniques, those conventions and values, which (2) one community from all others that belong to a different tradition.

The distinguishing mark of anthropology among the social sciences is that it includes for serious study other societies (3) our own. For its purposes any social (4) of mating and reproduction is as significant as our own. To the anthropologist our customs and those of a New Guinea tribe are two possible social schemes for (5) a common problem, and in so far as he remains an anthropologist he is (6) to avoid any weighting of one (7) the other. He is interested in human behavior, not as it is shaped by one tradition, our own, but as it has been shaped by any tradition (8) He is interested in a wide (9) of custom that is found in various cultures, and his object is to understand the way in which these cultures change and (10) , the different forms through which they express themselves and the (11) in which the customs of any peoples function in the lives of the (12) .

Now custom has not been commonly regarded as a (13) of any great moment. The inner workings of our own brains we feel to be uniquely (14) of investigation, but custom, we have a way of thinking, is behavior at its most commonplace. (15) , it is the other way round. Traditional custom is a mass of detailed behavior more astonishing than (16) any one person can ever evolve in individual actions. Yet that is a rather (17) aspect of the matter. The fact (18) first rate importance is the predominant role that custom (19) in experience and belief, and the very great varieties it may (20)

10()

A.deviate

B.fluctuate

C.differentiate

D.segregate

单项选择题