Types of Special Surveying Instruments and Their Uses
Civil engineering surveys often require the use of special surveying instruments for specific purposes. These instruments, which differ from general surveying equipment such as compasses, levels, and theodolites, are specifically designed for certain tasks and come with their own unique setups. This article will discuss the types of special surveying instruments and their uses.
Optical Rangefinder
An optical rangefinder is a surveying instrument that uses the principles of optics to determine distances between two points. It works by measuring the time it takes for a beam of light to travel from one point to the other and back, using the speed of light to estimate the distance. This instrument is mainly used for surveying long distances, such as those between two buildings.
Digital Theodolite
A digital theodolite is a surveying instrument that uses a computer to measure and record angles. It works by using a telescopic sight with built-in sensors to determine the direction and magnitude of angles. This instrument is mainly used for measuring angles in survey measurements, such as those between two points on a map.
Total Station
A total station is a surveying instrument that combines a theodolite, an electronic distance meter, and a computer. This instrument is mainly used for measuring distances and angles in survey measurements, such as those between two points on a map. It is also capable of performing various calculations, such as triangulation and area calculations.
GPS Receiver
A GPS receiver is a surveying instrument that uses the Global Positioning System (GPS) to determine the position of an object on the Earth’s surface. This instrument is mainly used for measuring distances and angles in survey measurements, such as those between two points on a map. It is also capable of performing various calculations, such as triangulation and area calculations.
Laser Scanner
A laser scanner is a surveying instrument that uses laser beams to measure distances and angles. It works by sending out a beam of light which is then reflected off of objects, with the reflection being measured by the instrument. This instrument is mainly used for measuring distances and angles in survey measurements, such as those between two points on a map.
Types of Special Surveying Instruments and Their Uses
The special instruments used in surveying are:
- Jig telescope and jig transit
- Telemeter
- Collimator
- Altimeter
- Electronic theodolite
Jig Telescope and Jig Transit
Industrial Surveying: From Conventional to High Precision
In the past, industrial surveying relied on conventional tools such as transit and levels. However, modern times require more accurate results and so jig telescope and jig transit have been developed to meet this need. These instruments are specifically designed for optical tooling and are able to measure down to the 1000th of an inch due to the use of optical micrometers.
Telemeter
What is a Telemeter?
A telemeter is a surveying instrument used to directly measure horizontal distances. It consists of a telescope with a counterweight at one end and a Vernier scale with a micrometer drum at the other. When used in the field, the image of the Vernier is brought into the center of the telescope and the micrometer drum is rotated until the Vernier and main scale graduations align. This provides a reading that represents the slope distance along the line of sight.
How to Calculate Horizontal Distance with Telemeter?
When using a telemeter to measure the horizontal distance, the inclined distance (L) and angle of inclination (x) must be taken into consideration. The horizontal distance is calculated by multiplying the inclined distance (L) by the cosine of the angle of inclination (x). In other words, the horizontal distance (H) is equal to L * cos(x).
Collimator
- Converting a Telescope Into a Collimator
A standard telescope can be transformed into a collimator by replacing its eye piece with an eye piece lamp. The lamp must be focused to infinity, allowing the telescope to serve as an accurate reference mark for optical tooling. In addition, collimators come with four adjustable levelling screws for increased accuracy in measurement.
- Benefits of a Collimator
Using a collimator has the key advantage of providing measurements that are independent of the instrument’s position and distance from the collimator to the station. Furthermore, the eye piece of the collimator can be changed to various levels of zooming to offer more precise viewing of targets.
Altimeter
Barometric Leveling Using Altimeter
Barometric leveling is a surveying method used to determine the vertical difference between two points. Traditionally, aneroid barometer was used for this purpose, but it had significant errors. Altimeter, on the other hand, is more accurate and is now the preferred instrument for barometric leveling. Furthermore, air-recorder may also be used to photograph the survey area.
Effect of Temperature on Altimeter
Temperature is a major factor affecting the accuracy of an altimeter. As an altimeter measures the atmospheric pressure of the surrounding air, temperature has a direct effect on this measurement. Altimeters are typically calibrated to a standard temperature of 10°C. If the observational temperature is higher than 10°C, then this will result in an elevation difference. A correction of 0.2ft for every 100ft elevation difference needs to be applied if the temperature is above 10°C.
Impact of Temperature on Altimeter Readings
Temperature has a significant impact on the readings of an altimeter. As the device is designed to measure the atmospheric pressure of the air around it, a change in temperature affects the accuracy of the readings. Altimeters are usually calibrated to a standard temperature of 10°C. If the temperature is higher than 10°C, then the elevation difference will also be greater. A correction of 0.2ft for every 100ft elevation difference needs to be applied if the temperature is above 10°C in order to ensure accuracy.
Electronic Theodolites
What Are Electronic Theodolites?
Electronic theodolites are advanced surveying instruments used to measure angles and other points of reference in the field. They are equipped with an opto-electronic scanning system, a control panel complete with a keyboard and LCDs, and a clear display for easy reading.
Benefits of Electronic Theodolites
Using electronic theodolites, surveyors can quickly and accurately measure angles and other survey points. The device’s control panel is outfitted with a keyboard and multiple-function keys, allowing users to easily create and manage tasks. The LCD display also provides a clear reading of measurements taken in the field.
Advantages of Electronic Theodolites
The advantages of electronic theodolites over traditional surveying instruments include their superior accuracy and speed, as well as their ability to precisely measure angles and other points of reference. Additionally, their control panels are user-friendly and allow for quick and easy task management. The clear LCD display also makes it easier to read measurements taken in the field.
Advantages of Electronic Theodolites in Surveying
Electronic theodolites offer many advantages when it comes to surveying. They are especially useful for their speed and accuracy in measurements, as well as their ability to store measurement values without needing to record them on paper.
Benefits of Electronic Theodolites
The use of electronic theodolites in surveying allows for greater accuracy and efficiency in measurements, as well as the ability to store the data without manually writing it down. This makes the surveying process much quicker and more accurate than it would be otherwise.