Modern repair and construction works are not complete without the use of precision instruments for measuring - levels. With their help, they measure the difference in height between points of space that are distant from each other. In this case, both devices give a reverse image due to the optic tubes.
Theodolite measures the vertical and horizontal angles, and the level allows you to set the exact location of the object in space.
This measurement process is called leveling. It can be hydrostatic, barometric, trigonometric and geometric.
The main difference of a theodolite from a levelBack to table of contents
The main differences when using optical measuring devices
Basic controls leveling.
The widespread use of laser measuring equipment in construction does not allow to ensure the final victory over theodolites and levels, which have always had a traditional use in conducting geodetic works. What is the difference between the studied devices?
What effect does the error have on measurement accuracy? Are there special restrictions that should not be overstepped? How to take into account the height of the terrain for building maps? These questions can be answered, knowing the distinctive features of a theodolite and leveling.
Theodolite is a device that allows to measure both horizontal and vertical angles. The tool allows you to accurately determine the magnitude of the measured angles between different points in space. The importance of linking buildings to specific points is related to measuring the angles between them in space. Taking into account the results obtained, it is possible to make a markup of the contour of buildings, the profile of the road and other quantities determined by the exact measurement of the result.
Measurements made using an optical theodolite are divided into 3 classes. This can include such types of device as:
- Exact optical theodolites, which provide an error within 2-5 seconds, such models are the most running during construction work.
- Precision, which help to ensure the error in the range of 1 second.
- Technical optical theodolites with an accuracy of 1 minute.
They are used in the field of land improvement, in forestry and other places, the study of which does not require measurements with high accuracy. With the help of precision theodolites, you can track the deformation of buildings, which occurs over time depending on the influence of environmental conditions and its own weight of construction objects.Back to table of contents
High-quality measurement devices
Construction professionals apply high quality requirements for construction sites, which have always increased with time. In order to meet all the necessary requirements for the erection of buildings, builders must take many different measurements to determine the inaccuracies made during the work. This allows you to move the entire construction process further, taking into account all the errors that will be corrected in a timely manner.
High-quality conduct of all measurements requires the use of geodetic instruments that are part of a fairly large group of measuring instruments. A specific measuring instrument is designed to perform specific measurements. At the same time, there are instruments for measurements that are multi-profile with a wide range of possibilities.
If we compare two devices for special measurements, then the use of a theodolite is associated with the most universal measurements compared to a level whose specialization is narrower. Despite this, both types of measuring devices have a wide range of applications.
Theodolite is characterized by a two-channel optical system, which provides the mechanism with the most independent and reliable system associated with the construction of an image of 2 circles that are in the plane of one scale. Theodolite reference system is associated with the use of a microscope, which has a certain price division. To separate the circles of theodolite single strokes are provided.Back to table of contents
What are the levels used for surveying?
For different types of measurements, different types of levels are used, which are distinguished by the type of instrument and the principle of its operation. Use laser and digital levels that are electronic. The use of such devices as optical levels allows the process of geometric leveling.
The measuring instrument has a telescope with an eyepiece. For fixing the pipe, use a special stand with a support platform, as well as a system of screws, which allows rotation of the level to the side in the horizontal plane.
You can reinforce the optical level with the help of lifting screws that allow you to give the tool the necessary working position. It is possible to make horizontal movement when taking the necessary reference point through the use of an elevation screw. To keep the sighting axis, which is horizontal, an automatic compensator is provided in the level, allowing you to increase not only the speed with which the measurement process is performed, but also their accuracy.
The use of a geodesic instrument, which may also be an electronic level, allows for more accurate measurements. The availability of the instrument software is connected with the possibility of real-time processing of the obtained measurements, which is done with maximum accuracy. The storage device helps to fix all the obtained measurement values.Back to table of contents
Characteristics of a design of a laser level
The measurement scheme level.
Today, laser levels are widely used in construction, the design features of which are associated with the ease of use of these tools. The principle of operation of optical, laser or electronic levels differs, depending on the mechanisms of the instruments. For example, the design of a laser level is characterized by the presence of a laser emitter that delivers a laser beam into space in the presence of an optical prism.
The laser beams, which emanate from the level, lead to the formation in the open space of two planes located perpendicularly, which intersect each other. If you are guided by them, then it is possible to make alignment of various surfaces (walls, floor, doorways). The work of such levels allows you to call them positional or static.
Allocate laser levels of rotational type. They are distinguished by an accelerated pace of work due to the built-in electric motor, which allows the laser emitter to be rotated through 360 °.
The role of a prism in such devices is performed by focusing lenses creating a point in the outer open space, which is visible with the naked eye. This point turns into a line, which is an ideal line. This type of levels is used for the purpose of carrying out the repair and finishing works connected with pasting on walls of wall-paper, laying of a tile, the device of plinths, etc.Back to table of contents
What design features has a theodolite?
Scheme device theodolite.
Theodolite is a device that allows to measure horizontal and vertical angles on the ground. The first theodolites had a ruler, which was placed at the very tip of the needle in the center of the goniometric circle. The rotation of the ruler on the tip of the needle resembled the movement of the needle of the compass.
The ruler had special cuts through which the threads were played, playing the role of reporting indices. The goniometric circle in the center was combined with the top of the measured angle, after which it was firmly fixed.
Then the first side of the corner was combined with the ruler, which was turned, taking into account the count No. 1 according to the scale, which the goniometer had. The second side of the corner was then combined with a ruler, noting the countdown No. 2. Next, we found the difference between the values of samples No. 2 and No. 1, and the result was equal to the angle. The movable ruler was called alidade, and the word "limb" was the name of the goniometric circle. To combine the ruler and the sides of the corner, the viziers were used, which were still at a primitive level.Back to table of contents
Devices that are part of the theodolite design
The scheme of measuring the vertical angle of theodolite.
Modern theodolites are characterized by the same principles of operation and the names of structural elements. The idea of measuring angles is associated with the presence of a telescope that combines the alidade and sides of the angle. The pipe must be rotated not only in height, but also in azimuth.
The device has a device on the dial scale, which allows you to read. For the construction of a theodolite, a robust metal casing is provided. In order for the alidad with the limba to be brought into smooth rotation, a system of axes is provided.
The process of moving in a circle of these elements is regulated with the help of clamping screws. To establish a theodolite on the surface of the earth, use a special tripod. There is also an optical plummet (filament oats), which allows to combine the plumb line and the center of the limb.
The sides of the angle during its measurement should be designed on the plane of the limb by a vertical plane, which is movable and is called collimation. The sighting axis of the telescope is involved in its formation when it rotates around its own axis.
Theodolite has, in turn, horizontal and vertical threads arranged in diameters. Thanks to these threads is sighting. When two horizontal threads are located at an equal distance from a simple cross thread, which is horizontal, they are called rangefinders.Back to table of contents
Differences in theodolite and level devices
The main differences between the measuring instruments of the level and theodolite are related to the design of their mechanisms.
Diagram of the elements of the optical level.
The differences of instruments can be noted in the presence of a two-channel reference system for the theodolite and the measuring rod with the strokes at the level. In the first case, the optical system assumes the presence of a microscope that has a certain price of division. With the help of strokes applied to the rail of the level, measurements are made in meters, centimeters, millimeters.
Theodolite, due to its versatility, has a perfect reference system related to digital indexing, therefore, the industrial industry has launched production of various modified devices. The modern device of theodolite differs from the basic model by the presence of the compensator, which is responsible for the operational installation of the additional possibility of sighting.
Unlike a level, the theodolite of any design can be applied on two levels at once. Not only on a horizontal level, like a level, but also on a vertical one. The development of instrumentation involves the development of the production of theodolites, which are distinguished by the technical characteristics of a higher level, which also applies to their operational properties.
The scope of theodolite is wider than the level, due to the possibility of conducting accurate studies and calculations. If we compare two types of devices, then for a certain class of the level used, specific requirements are provided.Back to table of contents
Conditions for the qualitative application of theodolite and level
Example of theodolite survey table.
Surveyors prefer to have at once two instruments for research, each of which is convenient for certain measurement conditions. In practice, it is planned to apply an improved recording, which will no longer be a sketchy one, as before the level.
In a few years the theodolite, without which it is impossible to manage in geodesy, will have a highly equipped construction. For example, it will be possible to use special search circles in the device.
If surveyors have to work in open space, the use of a laser level may not be as convenient as taking measurements with a theodolite. This is due to the fact that in bright and inhomogeneous illumination the laser beam of the level can be overlooked. In general, for field conditions of measurement, a traditional theodolite is a more useful optical device that does not require batteries or a battery for operation.
Theodolites telescopes are equipped with grids of four kinds of threads. The point of intersection of the filaments of the grid and the optical center of the lens is called the tube's sight axis. The manufacture of the device is connected with the installation perpendicular to its vertical axis, which is the main one. With a precise installation of the vertical axis, any rotation of the telescope, which is fixed in the zero position, the position of the sighting axis should be connected with the horizontal plane. This property of a level is basic as its pipe can have only zero position.Back to table of contents
The main difference between the level and theodolite in their practical applicationBack to table of contents
How is the installation of a tripod measuring tools
At installation of a support of a level plumb is not required. It is necessary to monitor the head of the device so that it takes a more or less horizontal position.
Theodolite survey scheme.
If you want to install a theodolite, the tripod for it must be centered. For this purpose, a plumb line is attached to the stalled screw. The tripod is installed so that the plumb line is closer to the center of the peg, which serves to mark the standing point of the tool.
The tripod adjustment should be done by pushing the legs apart and moving them to more securely fasten a measuring instrument equipped with a telescope. After this, the rams of the tripod should be fastened and the adjustment should be made more precisely by pressing the foot on the protrusion of the specific leg.
When this procedure has come to an end, the level or theodolite is removed from the case or box to install the instrument, aligning the ends of the lifting screws with special notches on the tripod head. Then it is necessary to unscrew the screws that are lifting at an equal height, and to fix the tool on the tripod.Back to table of contents
How to install the instrument on a tripod
Lifting screws and levels allow further installation of the level or theodolite. This is due to the need to bring the main vertical axis in the vertical position. If you install the level, then click on the protrusion of each leg of the tripod so that the circular level is in the center position.
Next, the telescope should be placed in a position that is parallel to the line of the two lifting screws. When rotating in different directions, the bubble attached to the telescope should be brought to the middle position.
Then repeat the rotation of the telescope, setting it parallel to the line, which refers to the other two screws. As a result, the level should again be in the middle position. Then any turn of a telescope of a level will not bring its bubble from the given position.Back to table of contents
Distinguishing characteristics of the measurement error
The use of an optical level is associated with the determination of the relative value, which indicates the degree of understating or exceeding of any mark relative to the point associated with the installation of the level. Using an optical level, make the necessary measurements of the distance to the rail.
It is important to accurately determine the angles in the horizontal plane. However, this is enough to make a breakdown of the foundation for a country house. In this case, it is not necessary to use an expensive optical theodolite for this purpose.
Often, the optical level has a measurement error that is lower than the error of the most expensive laser device with high accuracy. For conventional models of devices, the error will be about 2 mm per 1 km of double stroke. For this reason, the use of an optical level is more common for longer distances and an accurate measurement result.
For optics of any level, the minimum degree of rail removal from the installation point of the tool is typical, which is 0.4 m. This value is sufficient to allow the construction work to be carried out even for objects of minimal importance.