数字地形模型考题.doc

考试时间：6月8号，8:0010:00；鉴3-10名词解释： 1）Progressive Sampling :It is carried out in a grid pattern whose interval changes progressively from coarse to fine over an area(E25)2) LIDAR: AS LIDAR is an active system, it sends off electromagnetic energy and records the energy scattered back from the terrain surface and the objects on the terrain surface.(E53)3) INSAR: It is a technology that a pair of SAR images of the same area taken at slightly different position can be used to form an interferogram and the phase differences recorded in the interferogram can be used to derive a topographic map of Earths surface.(E43)4)DGPS: It is to determine the difference of coordinates between two points ,one of which is known precisely.(E61)5)DPW: It is an automated system .When given an image point of the left image ,the system will search the corresponding point on the right image automatically.(E39)6)DTM: A DTM is an ordered set of sampled data points that represent the spatial distribution of various types of information on the terrain.(后面的还有个公式，见E8，自己加上去)7)Least-squares fitting: (重点是公式，见书上E124)A simple definition could be that the sum of the absolute values of the errors is at a minimum. Another popular definition is the square errors being minimum, leading to the least squares, which is widely used in error theory.(E122)8)Constraints Delaunay Triangulation: Delaunay Triangulation with consideration of a given constrain is constrained Delaunay Triangulation, these constraints are a given set of data points and a set of lines.(E101)填空题1) DTM has wide applications in all geo_sciences and engineering, such as flight simulation, battle simulation, tank route planning, missile and airplane navigation.2) Distribution , density and accuracy are attributes of sampled source data.3) The accuracy of sampled data largely depends on the methods used for measurement, such as the mode of measurement, instruments used ,technique adopted.4) There are three basic orientations in the procedure of photogrammetry: interior, relative, absolutely.5) Three type of possible relations between elevation values of neighboring contours are: increase in elevation, decrease in elevation, equal elevation.6) Generally speaking , there are three type of models in the world: conceptual, physical, mathematical.7) The complexity of a terrain:（光谱频率，分形，曲率，半方差）Frequency Spectrum ,Fractal Dimension, Curvature, Semivariogram.8) From the statistical point of view ,a terrain surface is a population and the sampling can be carried out either: randomly or systematically.9) Three major characteristics of modern maps: measurability, generalization ,intuition.简答题1) 为什么说坡度能够定量表达地表起伏（中文作答19）通过坡度可以描述地面的复杂度，因为坡度描述的是地形表面在某一点的倾斜程度，并且是通过垂直和水平两个方向来描述，事实上夜就是通过地形表面的凹面和凸面来描述地形表面的特征，即地表的陡峭方向和大小，所以说坡度是描述地表复杂度的基本方法2）简述空间采样的原理以及空间采样的策略(E21+24)Sample Theory: If a function g(x) is sampled at an interval of d, then the Variations at frequencies higher than 1/(2d) cannot be reconstructed from the sampled data.Sample Strategy: 1)Selective Sampling: Very important points plus other points 2) Sampling with one Dimension Fixed :Contouring and profiling 3)Sampling with two dimensions fixed: Regular Grid and progressive sampling 4)Composite Sampling: An integrated Strategy2) 列表阐述TIN和GRID建模有哪些区别和联系（E）(答案不确定，自己再看看PPT或者书)1. 相对传统的模拟地形的表达，数字地形模型有何特点？E 7a. A variety of representation form；b.No accuracy loss of data overtime；C.Greater feasibility of automation and real-time processing D.Easier multi-scale representation 2. 画图绘出数字地形表达的分类方法 中P33. 简述渐进式采样有何缺点？E 26A.The sampled data points exhibit a high degree of redundancy in the proximity of abrupt changes in the terrain surface B.Pertinent features may be lost in the first run with its wide（coarse）spacing.These cannot be recovered by the following sampling runs.C.The tracking path is rather long，which decreases efficiency.4. 画图简述两种等高线内插方法.中P74一种方法 ：沿预定轴线方向的等高线直接内插，在这种方法中使用的预定轴线数目可能有一条，两条或四条另一种方法：沿内插点最陡坡度的内插，在这种方法中，相邻等高线上沿最陡坡度上的两点被首先搜索出来，然后根据这两点线性内插出格网节点的高程值5. 内插和表面建模有什么区别C 65 Interpolation includes the whole process of estimating the elevation vales of new points，which may in turn be used for surface reconstruction，while the latter emphasizes the process of actually reconstructing the surface，which may not involve interpolation. And，interpolation has a much wider scope.It may include surface reconstruction and the extraction of height information form the reconstructed surface；it may also include the formation of contours either from randomly located points or from a measured set of elevation values obtained in a regular grid pattern. 内插包括估计一个新点高程的整个过程，这个新点可能随后被用于表明重建。但表面建模强调重建表面的实际过程，这个过程或许并包括内插的计算。 而且内插包含了更为广泛的内容，它可能包含了表面重建，以及重建表面提取高程信息的过程，也可能包含了根据随机分布数据点或从规则格网中获取的高程量测值生成等高线的过程。6. Delaunay三角网构建的基本原则。Ca. TIN是唯一的b.力求最佳的三角形几何形状，每个三角形尽量接近等边形状。C.保证最近点的点构成三角形，即三角形的边长之和最小。7. 画图绘出数字地形建模的整个过程。E108. 摄影测量方法采集DTM时的共线方程。中文书P33要是中文作答的话，自己翻译下9. 简述数字地形模型建模的方法。E69 For the basic geometric unit used in modeling，the following approaches can be identity：a. point-based surface modelingb. triangle-based surface modeling c.grid-based surface modelingd. Hybrid surface modeling According to the type of source data used，modeling can be divided into two type：a.direct construction from measured data.b.indirect construction from derived data.10. 格网型DTM生成有哪些基本方法？E81 A. Coarser grid network formation from finer grid data：resamplingB. Grid network formation randomly distributed dataC. Grid network formation from contourd