S, Dept. It is a combination of an electronic theodolite transit , an electronic distance meter EDM and software running on an external computer known as data collector. When these instruments are combined and interfaced with EDMs and electronic data collectors, they become total-stations or electronic tacheometers ET. With a total-station one may determine horizontal and vertical angles together with slope distances from the instrument to points to be surveyed. With the aid of trigonometry and triangulation, the angles and distances may be used to calculate the coordinates of actual positions X, Y, and Z or northing, easting and elevation of surveyed points, or the position of the instrument from known points, in absolute terms.
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Surveying This blog is purely dedicated to discuss the theories, procedures and methods of Surveying. In case you are someone who is from Civil Engineering field, this blog will improve or keep you in touch with this art. So, after reading the articles, subscribe yourself through the email to keep track of the posts.
The known distances are either assumed to be horizontal or the geodetic lengths at the mean sea level MSL. The distances are measured directly as in the plane surveying or they are computed as in the geodetic surveying. In the first way, we can measure the horizontal distance between the given points if it is accessible.
We take the observation of the vertical angles and then compute the distances using them. If the distances are large enough then we have to provide the correction for the curvature and refraction and that we provide to the linearly to the distances that we have computed. In the second way, i.
The corrections for the curvature and refraction are applied directly to the angles directly. Now we will discuss the various cases to find out the difference in elevation between the two.
When the two points are at a known horizontal distance then we can find out the distance between them by taking the vertical angle observations. Trigonometric Leveling If the vertical angle of elevation from the point to be observed to the instrument axis is known we can calculate the vertical distance using trigonometry. The difference in lines of sights is same as the staff readings difference, when the staff is kept at a little distance from these two points.
So we can get the solution for the vertical distance easily. This gives us the difference in the line of the sights between the two points of instrument station.
Then again we do the same. Again we will take the vertical angular observations from the two instrument stations also and then we can apply the sine rule to solve the horizontal distances of the triangle. With the help of these angles and the distances we can get the vertical distance between any two point Instrument station and the top of object.