【正文】 the basis for various measurements, such measurements as control measurements. Within a certain area topographic mapping and engineering measurements to establish control work (regional control work) carried out survey work. Divided into horizontal control and vertical control survey measurements. Horizontal control work and vertical control work of the general layout separately, can also be laid into a threedimensional control work. Control work has control of the situation, limiting the role of measurement error accumulation is the basis of the survey work. For topographic mapping, grade control is the basis for expansion of root control to ensure that the measured topographic maps can be spliced with each other as a whole. For the engineering survey, which require special control work layout, construction setting and deformation as the basis for observation. Horizontal Control Network Include: (1) Triangulation: triangulation to establish horizontal control work of the basic methods. However, triangulation (lock) to require every point and more links between adjacent points, as, in the hidden areas often need to build a high survey markers. (2) Traverse: Travers simple before and after each point and two points only through television, point to facilitate the election, especially in hidden areas and buildings are many and difficult watching the city, convenient and flexible application of them. As the electromagic wave range finder development of wire measurement is widely used. (3) triangular measurement: measuring work trilateration asked all the side. Application of electromagic distance measurement can be carried out after determination of the side of Solution. Check this method fewer conditions, the lower the accuracy of azimuth projection. Vertical Control Network Include: (1) Leveling: The standard of measurement to establish the elevation control work known as the standard work. Regional level and accuracy level of work and national level work of the same. Elevation control work can be a full cloth mesh can also be laid classification. Each grade level can be measured as the heads of the surveyed area height control. Primary general layout as ring works, encryption can be laid as to satisfy the line or node work. Measurement of elevation height system of national reunification should be adopted. Joint testing of small test areas difficult, they can be assumed that elevation. (2) trigonometric leveling: trigonometric leveling is based on two points between the calculated vertical angle and horizontal distance to derive the elevation height difference, its accuracy is lower than the standard of measurement. Terrain often large, difficult to measure directly the standard triangular area measured elevation points for the topographic mapping to provide elevation control. Trigonometric leveling can use a single line, closed loop, work nodes in the form of work or elevation layout. Trigonometric leveling routes are generally shorter and the height difference smaller side of the edge ponent, starting and ending at the level associated with the elevation measurement points. In order to ensure the accuracy of trigonometric leveling work, work should be a certain number of known elevation points, these points or by direct leveling Leveling obtained. In order to eliminate as much as possible the Earth39。用測量不確定度表征測量結果不確定性，既要考慮測量結果的系統(tǒng)誤 差效應，又考慮了測量結果的隨機誤差效應，嚴格說還考慮了測量結果的模糊效應，所以測量不確定度具有嚴密的科學性與嚴謹性，是測量結果不確定性的精確描述。最小二乘法是一種數(shù)學優(yōu)化技術，它通過最小化誤差的平方和找到一組數(shù)據(jù)的最佳函數(shù)匹配，是用最簡的方法求得一些絕對不可知的真值。于是問題歸結為確定中的常數(shù)和使為最小，用這種確定系數(shù)的方法稱為最小二乘法。為了提高成果的質(zhì)量，處理好這些測量中存在的誤差問題，觀測值的個數(shù)往往要多于確定未知量所必須觀測的個數(shù)，也就是要進行多余觀測。 平差原理 測量平差是用最小二乘法原理處理各種觀測結果的理論和計算方法。當測區(qū)中部遠離 3176。在個別情況下，小測區(qū)也可采用假定坐標和磁北定向。對于區(qū)域性平面控 制網(wǎng)，根據(jù)測區(qū)面積、發(fā)展遠景、因地制宜、經(jīng)濟合理的原則，在保證控制點的必要精度和密度的情況下，可以一次全面布網(wǎng)，也可以分級布網(wǎng)。測角有利于控制方向誤差，測邊有利于控制長度誤差。一、二等水準路線定期重復測量 ,用以研究地殼垂直運動。為保證三角高程網(wǎng)的精度，網(wǎng)中應有一定數(shù)量的已知高程點，這些點由直接水準測量或水準聯(lián)測求得。各等級水準測量都可作為測區(qū)的首級高程控制。 （ 2） 導線測量： 導線測量布設簡單，每點僅需與前后兩點通視，選點方便，特別是在隱蔽地區(qū)和建筑物多而通視困難的城市，應用起來方便靈活。 在一定的區(qū)域內(nèi)為地形測圖或工程測量建立控制網(wǎng)（區(qū)域控制網(wǎng)）所進行的測量工作。分為平面控制測量和高程控制測量。隨著電磁波測距儀的發(fā)展，導線測量的應用日益廣泛。首級網(wǎng)一般布設成環(huán)形網(wǎng)，加密時可布設成附合線路或結點網(wǎng)。為了盡可能消除地球曲率和大氣垂直折光的影響，每邊均應相向觀測。為了計算觀測高差的有關改正 ,沿一、二等水準路線還要實施重力測量。邊角共測可充分發(fā)揮兩者的優(yōu)點，提高點位精度。分級布網(wǎng)通常先布設大范圍的首級網(wǎng)，再分階段進行低級控制點的加密。三角網(wǎng)所需的起始邊長可用測距儀器直接測出。 帶中央子午線時，應以測區(qū)中部子午線為中央子午線，采用任意帶高斯正形投影（見高斯－克呂格爾平面直角坐標系）。測量平差的目的在于消除各觀測值間的矛盾，以求得最可靠的結果和評定測量結果的精度。有了多余觀測，勢必在觀測結果之間產(chǎn)生矛盾，測量平差的目的就在于消除這些矛盾而求得觀測量的最可靠結果并評定測量成果的精度。 其精確定義可以從一組測定的數(shù)據(jù)中尋求變量之 間的依賴關系 ,這種函數(shù)關系稱為經(jīng)驗公式。 測繪中廣泛使用的測量平差法，是基于最小二乘原理的測量數(shù)據(jù)處理方法，它是利用直接測量采集觀測數(shù)據(jù)（觀測向量），再利用此觀測數(shù)據(jù)（ 觀測向量）結合平差 數(shù)學模型，對被測量結果進行估計的過程，估計方法采用 “ 數(shù)理統(tǒng)計學 ” 中著名的 “ 最小二乘法 ” 。隨機誤差（平差結果）是由于測量時的隨機因素或效應所引起的相對于被測量真值的偏差，這種隨機因素或效應，將導致重復測量時測量結果值的分散性。s curvature and atmospheric refraction perpendicular to the impact of observation on each side should be opposite. National leveling work Within the national territory, by a series of unified specifications laid by country and determination of the standard point of elevation posed by the work. Also known as the national vertical control work. The national economic construction, national defense a