Introduction
Plane table surveying is a very old surveying method that was used before the invention of electronic surveying instruments. It is still used today in some cases, especially when the terrain to be surveyed is too difficult to access with modern equipment. Plane table surveying is done by first setting up a plane table in the area to be surveyed. The plane table is a small, portable table that can be easily carried into the field. The surveyor then uses a compass and alidade (a type of sighting instrument) to take measurements and record them on the plane table. Once the measurements have been taken, the surveyor can then draw a map of the area on the plane table. This map can then be used to plan for construction projects, or for any other purpose. If you need to survey an area that is difficult to access, or if you simply want to try out a different method of surveying, plane table surveying may be right for you.
Theodolite
A theodolite is an instrument used for measuring angles in horizontal and vertical planes. It consists of a telescope mounted on a tripod, with graduated circles that rotate around the telescope’s axis. Theodolites are used in surveying and engineering applications to measure distances, angles, and elevations.
Theodolites can be used in conjunction with a plane table to create a topographical map of an area. This surveying method is known as plane table surveying. The surveyor sets up the theodolite at a point on the ground and measures the angles to two or more distant objects. These objects can be natural features like trees or hills, or man-made structures like buildings or fences. The surveyor then plots these points on a sheet of paper laid over the surface of the plane table. By connecting these points, the surveyor can create a contour map of the area.
Plane table surveying is a relatively simple and inexpensive way to create detailed maps of small areas. It is often used for preliminary surveys before more expensive and time-consuming methods are employed.
Plane table
A plane table is a flat surface on which a map or drawing can be placed for tracing or measuring. It is used in surveying and engineering to create two-dimensional representations of three-dimensional objects.
There are two types of plane tables: those that are fixed in position, and those that are mounted on a tripod and can be moved. The fixed type is usually attached to the ground or another object, while the tripod-mounted type can be set up anywhere.
Plane tables are often used in conjunction with a leveling instrument, such as a transit, to ensure that the surface is level. This is important for accurate measurements. Once the plane table is level, the surveyor can begin taking bearings of objects around them.
Bearing measurements are taken by aligning the sighting device on the plane table with an object in the distance and then reading the bearing off of the compass attached to the table. These bearings can then be transferred to a map or drawing, allowing the surveyor to create a two-dimensional representation of the area they are surveying.
Advantages of plane table surveying
There are many advantages of plane table surveying which make it a popular choice for surveyors. Some of these advantages include:
1. It is a relatively quick and easy method to set up and carry out.
2. It does not require expensive equipment, making it a more affordable option.
3. It is suitable for small to medium sized surveys.
4. It is ideal for surveys where detailed mapping is required, such as cadastral surveys.
5. Results from plane table surveying are generally very accurate.
Disadvantages of plane table surveying
There are several disadvantages of plane table surveying which include:
1. Time consuming: Plane table surveying is a very time consuming process as it requires setting up the plane table, leveling it, and then taking measurements at each station. This can be quite tedious and time-consuming, especially if there are a large number of stations to be surveyed.
2. Requires skilled personnel: Plane table surveying also requires skilled personnel in order to set up the plane table and take accurate measurements. This can make the process quite expensive as you will need to hire qualified surveyors.
3. Limited to relatively small areas: Plane table surveying is also limited to relatively small areas due to the nature of the equipment. This means that it is not suitable for surveying large tracts of land.
How to use a plane table
A plane table is a surveying instrument that allows the user to transfer measurements from the field to a paper or cardboard drawing. It consists of a flat surface, usually supported by a tripod, on which a drawing board is mounted. The plane table is used in conjunction with an alidade, which is an instrument used for sighting and measuring angles.
To use a plane table, first set up the instrument on level ground and make sure that the drawing board is parallel to the ground. Place a sheet of paper or cardboard on the drawing board, and secure it with tape. Use the alidade to sight an object in the distance, and then mark its position on the paper with a pencil. Repeat this process for several objects in different locations, until you have created a network of lines on the paper that represent the various angles you have measured.
Once you have transferred all of your measurements to the paper, you can use them to create a map of the area you surveyed. This can be done by scaling down the measurements, or by using a software program that can convert your data into a map.