查询词典 Dem.

The DEM in the new geodetic coordinate system on the ellipsoidal surface is different from the DEM in the projection plane.

基于此种坐标系在椭球面上建立DEM不同于基于地图投影概念的DEM。

Compared with traditional DEM or TIN based methods, this pure vector approach obtains not only the topological structure of drainage system in planar graph, but also the valley distribution polygon range. Depending on geometrical computation and judgment of vector line, polygon, the structured properties in drainage representation is enhanced, avoiding the case of noise disturbance in DEM based method. The core algorithm makes use of the ability of Delaunay triangulation in detecting hierarchical structure of each contour line.

中文摘要：基于Delaunay三角网模型在矢量等高线基础上通过弯曲特征分析，给出了一种地形结构特征提取及谷地树组织的方法，与传统的基于DEM或TIN数据结构提取地形特征的方法相比，该方法不仅得到了谷地系统在平面图上的拓扑结构，还获得了河谷在空间分布上的汇水范围，依托矢量线、多边形的几何关系判断，增强了谷地树组织中的结构化，避免了DEM方法中的噪音干扰，方法的核心是Delaunay三角网在单根等高线弯曲深度表达上的层次结构识别。

In the chapter 3, the development and characteristic of TM image and DEM is explained generally. In following chapter, how to measure backwater curve using remote sensing and DEM is particular expounded, including revise the backwater curve using water level data which is measured by hydrology station.

在第三章中概括性的叙述了TM遥感影像与DEM的发展过程及特点，在随后的章节中详细的阐述了遥感影像结合DEM测定水库回水曲线以及利用水位站点实测数据进行校正等内容。

On the basis of scaleless transform of DEM data, this paper introduces a method of extracting stream network after the generalization, and the fractal transformation of square root model, which is the same with the quantity-fixed generalization model of the stream networks.

本文在DEM数据无级变换的基础上，从DEM中提取出综合前后的河网，并引入分形扩展的方根模型，得到适用于河网的定量综合模型，从而评估出变换后DEM的比例尺。

Testing in terrain relief, and the algorithms can optimize the structure of TIN nicely.(2) According to the smoothness of the terrain and correlation between adjacency data points, the paper studied the possibility of smooth surface constructing of DEM based on TIN. Then based on Tayor fomula, vertical normal vector, triangular decomposition, continuous and smooth of surface and so on, a new kind of interpolate model of DEM was proposed based on TIN.

2分析原始地形起伏变化的连续光滑性以及邻近数据点之间的相关性，探讨了基于TIN的DEM光滑曲面构造的可行性，并基于二元泰勒公式、三角面剖分、曲面的连续光滑性等，提出了一种TIN上的DEM表面光滑插值模型，并通过构造数学曲面进行精度评估，并对模型进行了可视化分析。

The sixth part: Studies on the dynamic changes of soil retention function value of ecosystem in YUYANG District. Utilized ERDAS8. 5 to interpret the remote sensing image and get LUCC data and vegetation information of YUYANG District. Utilized R2V5. 5 to digitize administrative map, topographic map, vegetation picture, soil distribution map and meteorological website map. Utilized ARCINFOR8. 3 to change every digitization layer to the same projection, to generate Tyson polygon, to structure DEM and do vector polygon overlay. Utilized ARC VIE W3. 3 to obtain the grid data topographic slope and slope length from DEM data of YUYANG District, and then, turned every coverage layer into grid layer and do grid polygon overlay to gain data about dynamic changes of value of soil retention of ecosystem in YUYANG District, at last, the author analyzed the features of the spatial-temporal changes and its reason.The seventh part: Studies on the dynamic changes of fixing drifting sand against wind function value of ecosystem in YUYANG District.

第六部分：榆阳区生态系统土壤保持功能价值动态变化研究；利用ERDAS8.5对遥感数据进行解译获得榆阳区土地利用数据和植被信息，利用R2V5.5数字化榆阳区政区图、地形图、植被图、土壤分布图及气象站点分布图，利用ARCINFOR8.3对各数字化图层进行投影转换、泰森多边形生成、DEM构建和叠加分析，利用ARCVIEW3.3从DEM数据中获取榆阳区的坡度、坡长面域数据，并将上述各图层格网化，然后通过栅格图层叠加分析和代数运算获取榆阳区生态系统土壤保持功能物质量和价值量时空动态变化数据，最后分析了其变化的时空特点及形成原因。

The first is how to adequately define topographicst ructure morphol- ogically or hydrologically, and the second is how to design algorithms for the defined topographic structure. From the improving the approachs of the filling depressions and making gradient of plain in DEM, the extraction efficiency and result accuracy are better than existing methods and better fit to deal with the mass data of DEM.

通过对DEM中的洼地和平原区域处理算法的改进，使效率和结果准确性等方面都有了明显的改进，从而更加适合于对大范围流域的DEM数据进行处理与信息提取。

In this dissertation, through studying montanic grid DEM data in view of informatics, it is discovered that montanic grid DEM data possesses features of high information efficiency and low redundancy, which makes it impossible to gain high compression ratio with lossless compression methods.

用信息论观点对山区格网DEM数据进行了研究，发现山区格网DEM数据具有信息效率高、冗余度低的特点，揭示了用无损压缩对其进行压缩时效率较低的原因。

DEM is one of the important contents in photogrammetric.

DEM是摄影测量中的一个重要的内容，利用DEM生成等高线已经是摄影测量数字化作业中必不可少的环节，从内插DEM生成的等高线与原始等高。。。

Fractal theory is used to the interpolating method of DEM model to improve the accuracy of DEM model.

分析DEM模型插值的特点，把分形理论应用于DEM模型的插值方法中，提高DEM模型的精度。

Plunder melds and run with this jewel!

掠夺melds和运行与此宝石！

My dream is to be a crazy growing tree and extend at the edge between the city and the forest.

此刻，也许正是在通往天国的路上，我体验着这白色的晕旋。