外文翻译----控制测量的意义与方法(编辑修改稿)

外文翻译----控制测量的意义与方法(编辑修改稿)内容摘要：

scientific research to provide the ground point elevation, but also for Terrestrial Network, topographic measurement system to provide elevation control. Network of national standards adopted by the senior to junior, layout in several levels, sequential control, encryption. Form for each grade level closed loop route. The first and second line is the vertical control work level basis, along the tectonic stability of the traffic route steep, the layout and facilities with precise leveling measurements. The first and second level route regularly repeated measurements to study the vertical crustal movement. To calculate the observed height difference of the correction, along the first and second line will also carry the standard of gravity measurements. Third and fourth level line encryption first and second level of direct measurement system for the topographic maps provide elevation control. In order to establish a unified national control work, to establish a level base surface, as a work for all levels starting point elevation datum, usually the geoid as a standard base surface, it is a longterm coastal tide gauge sea surface fluctuation Observations were averaged and determined. Strictly speaking, different from the mean tide gauge sea to seek the same level as the base point of elevation, and the results vary. National level works generally use a tide gauge sea as determined by the average level of base level. Tide gauge stations in the vicinity of a permanent standard of origin, the level base surface and reliable calibration of the ground, measured by the leveling tide stations for the origin of the average sea surface elevation, calculated as the national standard height of the base work. Corner measurement Corner measurement point of view both the observation control work, but also measure side. Help control the direction of angular error, measured edge help control the length of the error. Measurement can give full play to the corner of the advantages of both, to improve location precision. In the engineering survey, not necessarily the perspective of observing works and all the side, you can angle the basis of additional testing part of the side, or in the test work based on the plus side some of the angle measured in order to achieve the required accuracy . Small triangle in a small test area is measured to establish a method of horizontal control work, which are used for small test area of the Primary Horizontal Control or third and fourth triangular following encryption, as a direct extension for topographic mapping in the Mapping Control Network (dot) foundation. In addition, Intersection encryption method is a method of horizontal control points. Known in two or more fixed observation point treatment of the horizontal angle, and find the location to be determined point plane, called the forward intersection method。 to be determined more than 3 points on the horizontal angle observations of known points, but find the location to be determined point of plane , called resection. Network by parison with the statecontrolled work, the former control the smaller, the control point density, point and the absolute error is less accurate. For the regional horizontal control work, according to the measured area, the development of vision, according to local conditions, the principle of economic rationality, control point in ensuring the necessary accuracy and density of circumstances, can a prehensive distribution work, you can grade cloth mesh. Grade cloth usually laid before the heads of largescale work of lowlevel control points in phases and then encrypted. Grade cloth mesh can be used with a new method, you can use different measurement methods. Design, should be accurate estimates, mapping the whole work control work accuracy requirement is relatively uniform. Surveying dedicated control work, sometimes in a wide range of high precision control work established within the local control work. Network by the general control work in the country under the encryption, or to the national control work for the initial data for the same coordinates system. If the measured area can no known control point when the optional point in work measurement with astronomical observation of its latitude and longitude, converted to Gauss Kr252。 ger Coordinate, as the starting coordinates. Also observing the astronomical point to another point azimuth, be converted into coordinates of azimuth, as the starting azimuth. In individual cases, a small test area can be used also assumes that coordinates and magic north direction. Triangulation can be required for the initial side rangefinder device directly measured. When the measurement area is small, can be regarded as flat. But in the larger area, you need to take into account the curvature of the earth. In order to deal with a reasonable length of projection distortion, should be properly chosen projection zone and perspective plane. Observation results of the general should go to the reference ellipsoid (or the geoid), the calculation ac。