In whole circle bearing (WCB) the bearing of a line at any point is measured with respect to a meridian. Its value varies from zero to 360°, increasing in clockwise direction. Zero is north direction, 90° is east, 180° is south and 270° is west (Ref. Fig. 13.2). This type of bearing is used in prismatic compass.
In reduced bearing (RB) system, bearings are measured from north or south direction towards east or west. Hence, angles are from 0 to 90° as shown in Fig. 13.3. This system of measuring bearings is used in Surveyor’s compass and it is also known as Quadrantal Bearing (QB). The bearing measured is designated with letter N or S in the beginning to indicate whether it is from north or south. The letter E or W written after the angle indicates whether the bearing read is towards east or west, respectively.
The conversion of the bearing from one system to the other system can be easily carried out by drawing a sketch to indicate WCB or RB as shown in Fig. 13.4. It may be observed that conversion table is as given below: