Table of Contents
How do you measure the angle of theodolite?
- The theodolite is first set up at o.
- Then plate bubble are brought to the center with the help of a foot screws and then the altitude bubble is brought to the center by clip screw.
- The telescope is raised slowly to bisect the point A accurately V to measure the angle of elevation.
How many types of angles can be measured from theodolite?
The theodolite consists of a telescope pivoted around horizontal and vertical axes so that it can measure both horizontal and vertical angles. These angles are read from circles graduated in degrees and smaller intervals of 10 or 20 minutes.
Which method is adopted to measure the angle by theodolite with good accuracy?
Repetition Method: This method is used for very accurate work. In this method; the same angle is added several times mechanically and the correct value of the angle is obtained by dividing the accumulated reading by the number of repetitions.
What can you measure with a theodolite?
theodolite, basic surveying instrument of unknown origin but going back to the 16th-century English mathematician Leonard Digges; it is used to measure horizontal and vertical angles. In its modern form it consists of a telescope mounted to swivel both horizontally and vertically.
How vertical angle is measured in theodolite?
If the points lie on the same side of the horizontal, the vertical angle between the points is the difference between the measured angles. If they lie on either side of the horizontal through the instrument, the vertical angle between the points is the sum of the angles measured.
Which method are used for measurement of horizontal angle by theodolite?
Choosing the most suitable method
| Section1 | Method | Equipment2 |
|---|---|---|
| 3.3* | Compass or protractor | Simple compass, protractor, drawing sheet |
| 3.3** | Plane-table | Plane-table drawing paper |
| 3.4* | Right-angle method | Measuring line |
| 3.5*** | Theodolite or transit | Transit level with graduated horizontal circle |
What are the types of theodolites?
There are two different kinds of theodolites: digital and non digital. Non digital theodolites are rarely used anymore. Digital theodolites consist of a telescope that is mounted on a base, as well as an electronic readout screen that is used to display horizontal and vertical angles.
How do surveyors measure angles?
For these reasons, land surveyors rely on transits (or their more modern equivalents, called theodolites) to measure angles.
How the horizontal and vertical angles are measured by theodolite?
A Theodolite is a measuring instrument used to measure the horizontal and vertical angles are determined with great precision. Theodolite is more precise than magnetic compass. Magnetic compass measures the angle up to as accuracy of 30′. Anyhow a vernier theodolite measures the angles up to and accuracy of 10”, 20”.
How do you measure angles in surveying?
To measure a horizontal angle, stand at the angle’s summit and measure the azimuth of each of its sides; calculate the value of the angle as follows. 10. If the magnetic north falls outside the angle, calculate the value of the angle between the two lines of sight as equal to the difference between their azimuths .
What are the three methods to measure horizontal angle?
Choosing the most suitable method
| Section1 | Method | Horizontal angle |
|---|---|---|
| 3.1* | Home-made graphometer | Medium to large |
| 3.2** | Magnetic compass | Medium to large |
| 3.3* | Compass or protractor | All sizes |
| 3.3** | Plane-table | All sizes |
What is deflection angle?
A deflection angle is the angle between the onward extension of the previous leg and the line ahead.
What is micrometer theodolite?
This instrument is a theodolite with micrometer screws attached to the circle reading system for improved precision in the reading of the horizontal and vertical circles. It is a 2 second first-order theodolite and is typically used for primary and secondary triangulations, traversing and geodetic astronomy.
What does a triangle mean in surveying?
Triangulation is a surveying method that measures the angles in a triangle formed by three survey control points. Using trigonometry and the measured length of just one side, the other distances in the triangle are calculated.
What are the 7 types of angles in surveying?
angle—The difference in direction between two convergent lines. Classed as horizontal, vertical, oblique, spherical, or ellipsoidal, depending on whether it is measured in a horizontal, vertical, or inclined plane, or in a curved surface.
What is geometry of theodolite?
The basic geometry of measuring with a theodolite is the same as that of an intersection. On the other hand such a theodolite can be assumed as a ficititious camera positioned on a station to take a photograph.
How do you read the vertical angle in theodolite?
Measuring Vertical Angles in Theodolite
- Set up the theodolite at the station from where the vertical angle is to be mea-sured. Level the instrument with reference to the plate bubble.
- Swing the telescope to approximately direct the line of sight towards the signal at P.
- Read the verniers C and D.
How do you calculate the angle of deflection?
The deflection angle is measured from the tangent at the PC or the PT to any other desired point on the curve. The total deflection (DC) between the tangent (T) and long chord (C) is ∆/2. The deflection per foot of curve (dc) is found from the equation: dc = (Lc / L)(∆/2).
What is a 12 cm theodolite?
A theodolite is designated by diameter of the graduated circle on the lower plate. The common sizes are 8cm to 12 cm while 14 cm to 25 cm instrument are used for triangulation work.
What is theodolite used to measure?
Theodolite: Introduction 2. Theodolite is used to measure the horizontal and vertical angles. when the objects are at a considerable distance or situated at a considerable elevation or depression ,it becomes necessary to measure horizontal and vertical angles more precisely.
How do you level theodolite?
Leveling of theodolite is completed by making the vertical axis of instrument truly vertical. It is done by centering the bubble in the level tube by rotating foot screws provided. The bubbling should be done in all direction of telescope and the centered bubble should not move while taking reading.
How to use theodolite tripod?
Setting means attaching theodolite to the tripod stand. The tripod is unfolded and placed on the ground with all legs in same level. In this operation, we level the tripod by just eye estimation. From the bottom of theodolite, a plumb bob is suspended to set the instrument over station mark.
How to set up the theodolite telescope?
The theodolite is first set up at o. it is then centered and level-led properly. The zeroes of the verniers are set at the 0 deg -0 deg mark of the vertical circle. The telescope is then clamped. Then plate bubble are brought to the center with the help of a foot screws and then the altitude bubble is brought to the center by clip screw.