第一节钢尺量距
　　 一、量距工具
　　 钢尺量距的主要工具是钢尺。钢尺又称钢卷尺，是用钢制成的带状尺，尺的宽度10～15mm，厚度约O．4mm，长度有20m、30m、50m等，基本分划有厘米和毫米两种。在每米及每分米处都有数字注记。基本分划为厘米的钢尺适用于一般距离测量。基本分划为毫米的钢尺，以及基本分划为厘米，但在起点处一分米内刻有毫米的钢尺，适用于精密量距。根据尺上零点位置的不同，钢尺有端点尺和刻线尺之分。
　　 端点尺是以尺的最外端作为尺的零点，如图6-1-1a)所示。当从建筑物墙边开始丈量时使用很方便。刻线尺是以尺前端的一条刻线作为钢尺的零点，如图6-1-1b)所示，在距离丈量时可获得较高的精度。

钢尺量距的辅助工具有标杆、测钎、锤球等。
　　 标杆用木材、玻璃纤维或铝合金制成，长2m或3m，直径3—4cm，用红、白油漆交替漆成20cm的小段，杆底装有锥形铁脚以便插入土中，或对准点的中心，作为观测点的照准标志，如图6-1-2a)所示。
　　 测钎由粗铁丝加工制成，长30-40cm，上端弯成环形，下端磨尖，常用于标定尺端点和整尺段数，一般以11根为一组，穿在铁环中，如图6-1-2b)所示。
　　 锤球由金属制成，外形似圆锥形，上端系有细线，它是对点、标点和投点的工具，如图6-1-2c)所示。

 二、直线定线
　　 在丈量两点间距离时，如果地面两点之间的距离较长或地面起伏较大，一个尺段不能完成距离丈量，则需要分段进行量测。为了使所量线段在一条直线上，需要在两点间的直线上，标定一些点，这—工作称为直线定线。一般量距用目视定线，精密量距用经纬仪定线。
　　 如图6-1-3所示，欲量A、B间的距离，一个作业员甲站于端点A后1-2m处，瞄A、B。并指挥另一位持杆作业员乙左右移动标杆2，直到三个标杆在同一条直线上，然后将标杆竖直插下。直线定线一般山远及近进行。

当量距精度较高时使用经纬仪定线，其方法与目估法基本相同，只是将经纬仪安置在A点，用望远镜瞄准B点进行定线。
　　 三、钢尺一般量距
　　 丈量精度要求达到厘米级时，用一般方法量距且采用目估定线。
　　 1．平坦地区的丈量方法
　　 平坦地区可沿地面直接丈量，可先在地面进行直线定线，亦可边定线边丈量。丈量时由两人进行，各持钢尺一端沿着直线丈量的方向，前尺手拿测钎与标杆，后尺于将钢尺零点对准起点，前尺手沿丈量方向拉直尺子，并由后尺手定方向，将尺的零点对准起始点，当前、后尺手将钢尺拉紧、拉平时，后尺于准确对准起点，同时前尺手将测钎垂直插到尺子终点处，这样就完成了第一尺段的丈量工作。两人同时举尺前进，后尺手走到测钎处停下，同法量取第二尺段，然后后尺手拔起测钎套入环内，沿定线方向依次前进，重复上述操作，后尺手手中的测钎数就等于量距的整尺段数n。最后不足一整尺段的长度称为余长。直线全长按下式计算：

Volume from the first section steel ruler
First, the amount of distance tool
Steel ruler from the main tool is the amount of steel ruler. Steel ruler also known as the steel tape is made of steel strip feet foot width of 10 ~ 15mm, thickness of about O. 4mm, length of 20m, 30m, 50m and so on, the basic partition are two kinds of centimeters and millimeters. In each m and each part has a number of decimetre Notes. The basic sub-classified as a centimeter ruler for distance measurement in general. The basic sub-classified as a millimeter ruler, as well as basic sub-classified as a cm, but at the starting point within a decimeter mm steel ruler engraved for the amount of distance precision. According to the different scale on the zero position, steel ruler engraved lines with endpoints feet and feet of the points.
Endpoint foot is feet, as the outer end of the zero-foot, shown in Figure 6-1-1a) as shown. When measured from the building when the wall started to use very convenient. Line scale is engraved on the front of a carved-foot line as the ruler's zero, as Figure 6-1-1b) shows, when measured at a distance of access to high accuracy.


The amount of aid from the ruler tool benchmarking, measuring drill, hammer ball.
Benchmarking with wood, glass fiber or aluminum, long-2m, or 3m, diameter 3-4cm, with red and white paint, painted alternating bits of 20cm, with cone-shaped iron rod at the end of legs in order to insert the soil, or alignment point the center of the observation points awarded as a sign shown in Figure 6-1-2a) as shown.
Measured by the coarse wire solder processed into long 30-40cm, the top bent circular, the lower sharpened, commonly used in the calibration of the entire foot-foot end-point and the number of segments, generally 11 as a group, wear the hoop, the Figure 6 -1-2b) as shown.
Hammer the ball is made of metal, shape like cone-shaped, the top tied with thin, it is a point, punctuation and investment point of a tool shown in Figure 6-1-2c) as shown.


  2, straight alignment
When measuring the distance between two points, if the longer the distance between two points on the ground or ground fluctuated considerably, and a foot section can not be completed measuring the distance, you need to carry out sub-measurements. In order to make the traffic segment in a straight line, need a straight line between two points, calibration of some point, this - working as a straight-line alignment. In general the amount of distance with the visual alignment, precision alignment of the amount of distance with the theodolite.
As shown in Figure 6-1-3, want the amount of A, B the distance between an operator can stand on the endpoint A A after 1-2m Department, the observable A, B. And directing the other one who shot the operator can move around pole 2 B, until the three pole on the same straight line, and then inserted under the vertical pole. Straight-line alignment far and near to the general Hill.


Equivalent from the use of high precision theodolite alignment of its methods and head estimation method is basically the same, but will be placed in A point theodolite with the telescope aim point B alignment.
Third, the amount of steel ruler from the general
To achieve centimeter-level measurement accuracy when the amount of distance with the general approach and the use of mesh lines assessed.
1. Flat area measuring method
Flat area can be directly measured along the ground can be carried out first in the ground straight alignment, can be measured while alignment edge. Measurement carried out by the two men, each holding one end of the ruler along the straight-line measurement of the direction of, the former ruler in hand soldering and benchmarking test, the latter ruler at the ruler zero point alignment, the former ruler in hand along the direction of straightening measuring ruler, and After the foot by a hand-out directions to align the starting point of zero feet, the current, post-foot steel ruler hand will be stretched, pulled in peacetime, the latter ruler to accurately align the starting point, while the former ruler in hand to plug into the vertical ruler measuring solder terminal Department, thus completing the first-foot section of demarcation. They also cite-foot forward, hand-foot walk test after brazing at a halt, with France taking second volume of foot section, then hand out this test after the solder sets foot into the ring, along the alignment direction of the order forward, repeat the above operation , after measuring the hands of hand-foot is equivalent to the amount of solder a few feet away from the whole number of segments n. Last less than a full foot in length as more than a long paragraph. Straight line length determined by the formula: