Plane Table Surveying
Plane table surveying is a graphical method of surveying in which the field works and the plotting is done simultaneously. It is particularly adopting in small areas mapping. Plane table surveying is used for locating the field computation of area of field.
Plane Table essentially consists of a Drawing board mounted on tripod stand and Alidade.
1. Drawing board mounted on tripod: A sheet of drawing paper, called plane table sheet is fastened to the board. Board is made up of well seasoned wood such as teak of size 40x30 to 75x60cm. it had plane and smooth top. It is mounted on a tripod in manner that it can be leveled. Leveling up of the table is done by shifting the legs of tripod. Some tripod provided with leveling screw or by ball and socket head for accurate leveling.
2. Alidade: Alidade consists of two vertical sight vane fitted at end the end of straightedge. The straight edge ruler usually made of brass or teak wood graduated beloved edge. One of the sight veins is provided with narrow slit and the other with a central vertical wire or hair. Beveled working edge alidade is called fiducial edge.
Fig. 6.1 Plane table with Alidade
Accessories used in Plane Table surveying are
Fig. 6.2 Accessories in Plane Table surveying