第一节 控制测量概述
　　 一、控制测量的任务和作用
　　 为限制测量误差的积累，保证必要的测量精度，使所测的每幅地形图精度均匀；使各分区测绘的地形图能够拼接成一个整体；使工程建设中整体设计的工程建筑物能够分区施工放样，就必须按照一定的测量原则首先在全测区范围内选定一些控制点，构成一定的儿何图形，用精密的测量仪器和精确的计算方法，在统一的坐标系统中，确定它们的平面位置和高程，再以这些控制点为基础进行碎部测量和施工放样等。
　　 在测量工作中，首先在测区内选择一些具有控制意义的点，组成一定的几何图形形成测区的骨架，用相对精确的测量手段和计算方法，在统一的坐标系中，确定这些点的平面坐标和高程，然后以它为基础来测定其他地面点的点位或进行施工放样，或进行其他测量工作。其中，这些具有控制意义的点称为控制点；由控制点组成的几何图形称为控制网；对控制网进行布设、观测、计算、确定控制点位置的工作称为控制测量。
　　 控制测量的任务可概括为：在丁程勘测阶段，测绘各种大比例尺地形图时，进行必要精度的控制测量；在工程建设施工阶段，进行一定精度的施工控制测量；在工程竣工后的营运阶段，为进行建(构)筑物变形观测而作的变形控制测量。总之，控制测量贯穿于工程建设的各个阶段。
　　 由此可见，控制测量的作用在于：它是进行各项测量工作的基础；它具有传递点位坐标并控制全局的作用；具有限制测量误差和积累的作用，还可以使分片施测的碎部点精确连结成为一个统一的整体。
传统的控制测量分为平面控制测量和高程控制测量。平面控制测量确定控制点的平面位置(x，y)，高程控制测量则确定控制点的高程(H)。
　　 二、平面控制测量
　　 测量控制点平面位置(x，y)的工作，称为平面控制测量。平面控制网的建立，传统方法主要有三角测量和导线测量，随着电子技术和航天技术的不断发展，全球定位系统(GPS)目前已广泛地应用于城市控制网的改造、控制点的更新和加密。
　　 在地面上选定一系列点构成连续三角形，若三角形向某一方向推进，这种图形称为三角锁，如图7—1—1所示，若三角形向四面扩展成网状．则称为三角网。测定各三角形顶点的水平角，并根据起始边长、方位角、起始点坐标利用正弦定律来推求各顶点平面位置的测量方法称为三角测量，这种控制点称为三角点，此控制网称为三角网。
　　 将地面上一系列点依相邻次序连成折线形式，如图7-1-2所示，并测定各折线边的长度、转折角，再根据起始数据推求各点的平面位置的测量方法，称为导线测量，这种控制点称为导线点，由它所连接而成的折线称为导线，此控制网称为导线网。

GPS控制测量是将GPS接收机安置在控制点卜，通过接收卫星信号加以处理，即可获得地面控制点的位置，其定位原理可参见第十一章第二节相关内容。
　　 三、高程控制测量
　　 测定控制点高程(H)所进行的测量工作，称为高程控制测量。传统高程控制网主要采用水准测量、三角高程测量的方法建立。用水准测量方法建立的高程控制网称为水准网。三角高程测量主要用于地形起伏较大、进行水准测量有困难的地区，为地形测图提供高程控制。
　　 四、控制网的布设原则
　　 控制网具有控制全局、限制误差累积的作用，是各项测量工作的基础和依据。控制网的布设应遵循整体控制、局部加密，高级控制、低级加密的原则。
　　 国家制定了一系列相应的测量规范，对各种控制测量的技术要求做了详细的规定。在测量工作中应严格遵守和执行《测量规范》。

Section Control Survey Overview
1, control tasks and the role of measurement
To limit the accumulation of measurement error to ensure that the necessary measurement accuracy, so that the measured accuracy of each piece of uniform topographic maps; to enable the district mapping of topographic maps can be spliced into a whole; so that the project construction, the overall design of engineering structures can be sub - Area construction setting, we must follow certain principles of the first measurement of the whole area within the test identified a number of control points, a certain degree of abuse Ho graphics, using precision measuring instruments and precise method of calculation in a unified coordinate system to determine the location and elevation of their plane, then these control points as the basis for pieces such as the Ministry of measurement and construction layout.
In the measurement of work, the first test with control meaning the area to choose some point to form a certain geometrical form the skeleton of the surveyed area, with a relatively accurate means of measurement and calculation methods, in a unified coordinate system to determine these points plane coordinates and elevation, and then based on it to determine the point and other ground points, or construction setting, or other measurements. Among them, the meaning of those controlling the points referred to as control points; by the control points of the geometry known as the control network; be laid on the control network, observation, calculation, to determine the location of control points is called control survey work.
Control of measuring tasks can be summarized as follows: in the small-range investigation phase, mapping a variety of large-scale topographic maps, make the necessary accuracy of control survey; in the construction the construction stage, to a certain accuracy of construction control survey; in operation after the completion of the project stage, for the purpose of building (structure) building material deformation observations and measurements made of the deformation control. In short, the control measurements throughout the various stages of construction.
Thus, the control measure's role is: it is the basis of the work carried out various measurements; it has a delivery point and coordinate and control the overall effect; has limited the role of measurement error and accumulation, but also can make measurements of the broken fragment Shi Department of point accuracy into an unified whole.
Measurement is divided into the traditional control plane control of measurement and control of measuring height. Plane Control Plane Survey to determine the control point location (x, y), height control is to determine the control point measuring height (H).
Second, Horizontal Control Survey
Measurement plane location of control points (x, y) work, known as the Horizontal Control Survey. The establishment of horizontal control network, the traditional methods include triangulation and traversing, with the electronic technology and the continuous development of space technology, global positioning system (GPS) has been widely used in the transformation of urban control network to control the point of updating and encryption.
Selected a series of points on the ground constitute a continuous triangle, if the direction of the triangle to a particular, this graph is called triangular lock, as shown in Figure 7-1-1, if the triangle to expand into the mesh on all sides. Is called triangulation. Determination of the horizontal angle of the triangle vertices and, based on the starting side length, azimuth, the starting point coordinates using the sine law to inquire the location of the vertex plane triangulation measurement method is called, the control points, known as the triangle point, this control network known as triangulation.
Will be a series of points on the ground in accordance with the order even as the adjacent broken line form, as shown in Figure 7-1-2, and to determine the length of the polyline edges, turning angle, and then start the data according to inquire the location of various points of the plane measuring method known as the wire measurement, such control points, known as the lead point, it is connected by a wire made of the broken line is called, this control network known as the lead network.



GPS Control Survey is the GPS receiver placed in the control point Pu, through the reception of satellite signals to be addressed, you can get the location of ground control points, positioning theory can be found in section II of chapter XI of relevant content.
3, elevation control surveying
Control points measured height (H) measurements carried out, called the height control surveying. Elevation control network mainly uses the traditional standards of measurement, trigonometric leveling method of establishment. The standard of measurement methods used to establish the elevation control network known as the standard network. Trigonometric leveling is mainly used for large undulating terrain to carry out the standard of measurement difficulties in areas of topographic mapping to provide elevation control.
4, control the layout of the principles of network
Control network with the control of the situation, limiting the role of cumulative error, is the basis and foundation survey. Control network should follow the layout of the overall control, partial encryption, advanced control, low-level encryption principles.
Countries have developed a series of corresponding measurements norms and technical requirements for various control measurements made detailed provisions. In the measurement of work should be strictly observed and implemented "measurement standard."