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[测绘知识]地形图的测绘
作者:成都新瑞测绘  来源:吉林省测绘局  浏览:1270次  更新:2009/8/18 9:30:58

人们看到一张张反映地球表面形态和面貌的地形图是相当复杂的。不论是地形起伏变化的山区,还是河流湖塘水网密集的水乡平原,图上各种各样的地貌和地物符号都准确地反映了地面的实际情况。它们是怎样测绘出来的呢?
        这首先要明确确定地形图上的每个点位需要的三个基本要素:方位、距离和高程。同时这三个基本要素还必须有起始方向、坐标原点和高程零点作依据。
        用一张固定在图板上的白纸测绘地形图时,一开始先要对图板定向,这可根据事先测量的大地控制点作为起始方向来定向;在简易测图中,也可用指北针来定向。图板定向后,就要确定测图点在图纸上的位置,对于纳入国家统一的基本地形图的测绘,是有统一规范的坐标展点要求的;但对于小面积局部地区测绘,可假设独立的平面直角坐标系原点,即可着手按测方位和距离两要素的方式,测定地面上其它任何点的平面坐标位置。至于点的高程,由于国家高程系统已在全国各地布设了很多统一高程基准的水准点可供利用,一般均可用水准测量方法连测到测图区,因此在测图时采用视距三角高程测量的方法就可同时测定出任何一点的点位和高程。
        我们知道,地面上任何地貌和地物的描绘都可用其变换点所组成的线条反映出来。地貌可用等高线反映出其高低和形态变化;地物如房屋、道路、河流等均可用其变换特征点所构成的线条表示出来;有不少特殊的地貌和地物还有专门的图例符号来表示。因此,测绘地形图的工作实际上就是测定并表示地面上所有地貌和地物的特征点。当然,不同比例尺的地形图,也还有个对特征点的取舍和繁简综合问题。
        随着测绘科学技术的发展和进步,现代地形图的大量艰巨的测绘工作也已由传统的野外白纸测图转向室内的航空摄影测绘和航天遥感测绘,并已逐渐迈向全数字化、自动化测图。

 

 

 

 

People see the faces reflect the face of the earth's surface morphology and the topographic map is a complicated matter. Whether changes in topography of the mountain, or river water network HUTANG plain water-intensive, the map features a variety of features and symbols are an accurate reflection of the actual situation on the ground. They are mapping out how to do?
         This is the first clearly defined topographic maps for each point on the needs of three basic elements: direction, distance and elevation. At the same time, the three basic elements must also have the initial direction and elevation coordinates of the starting point for the basis of zero.
         Fixed on the map with a white board mapping topographic maps, the first thing I have orientation on the drawing board, which can be measured in accordance with prior land control points as the initial orientation direction; Mapping in the summary, he can refer to North needle orientation. Drawing board after orientation, it is necessary to determine the point in mapping the location of drawings for the national reunification of the basic topographic map of the mapping, is a standardized point of the requirements of the coordinates outreach; but in some areas for small area mapping, can be assumed independent The plane Cartesian coordinate system origin, you can start by measuring the two elements of direction and distance of approach any other determination of the ground point coordinates of the location of the plane. As regards the point of elevation, elevation as a result of the national system has been laid throughout the country a lot of elevation based on a unified standard of points available, the general standard of measurement could be detected even mapping zone mapping is therefore used in trigonometric leveling horizon At the same time, the method can be determined at any point and the elevation of the point.
         We know that the ground topography and features of any description are available by the transformation point of the lines is reflected in the composition. Topography can be reflected in its high and low contour and shape change; features such as housing, roads, rivers, etc. can be used by its conversion feature points of the lines that constitute them; there are many special features of the landscape and there are special symbols legend to express. Therefore, the work of surveying and mapping topographic maps and is in fact determined that the ground topography and features all the feature points. Of course, different scales of topographic maps, but also still have the choice of feature points and the integrated character issues.
         With the mapping of science and technology development and progress, the modern topographic map of a large number of arduous work by mapping the field of traditional white shift mapping indoor aerial photography mapping and space remote sensing mapping, and has been gradually moving towards all-digital, automated test Fig.
 
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