竖直角测量教学中几个概念的讨论

THE DISCUSSION OF SOME CONCEPTS IN THE VERTICAL ANGLE MEASUREMENT TEACHING

任何一个角度都是由两个方向构成的 ,在水平角测量中 ,构成该角的两个方向的水平 (盘 )读数之差即为其水平角。竖直角则是两个方向的竖盘读数之差。不过构成竖直角的其中一个方向是水平 (视 )线。任何注记形式的竖直度盘 (简称竖盘 ) ,无论是盘左或盘右 ,当其视线水平时 ,其读数是个定值。在理想状态下 ,该读数是 90°的整数倍。所以测定竖直角实际上只需读取被照准目标 (方向 )的竖盘读数 ,即可求算得竖直角。在竖直角测量教学中 ,对于竖盘指标差及竖盘指标的正确位置等概念 ,在一些测量学教材中往往表述得不够确切。这样不仅使学生不易真正地弄懂 ,就连一些教师对此也理解得不很深透 ,从而造成讲解时有点似是而非 。

Any angle consists of two directions.In the measurement of the horizontal angle,the difference between the horizontal readings of the two directions that consists of the very angle can be perceived as its horizontal angle.The vertical angle refers to the difference between the vertical readings.However,one of the directions which consists of the vertical angle is horizontal.So on the vertical plate that records its readings in any marked form,whether it is left of right,its reading is a fixed value when its line of sight in surveying is horizontal.Under ideal circumstances,its reading is twice or three times as much as 90 degree.So actually the measurement of the vertical angle is gained from the vertical reading which is based on the aimed target. In the teaching of vertical angle measurement,as to the concepts concerning the correct position of vertical index mark and vertical index error,some textbooks haven't presented an exact description of it.As a result,not only students but also some teachers can not have a clear understanding of it.It is natural that the explanation given by some teachers is apparently right but actually wrong or even self-contradictory.