The red dot on the compass represents the gem line. The compass consists of three parts: the bottom of the sea, the inner disk and the outer disk. The quality of the three parts is closely related to the measurement accuracy of the compass. The quality of tools is related to the measurement accuracy, which directly affects the accuracy of vertical lofting.

There are three kinds of compasses, namely ternary compasses, ternary compasses and ternary ternary comprehensive compasses. Learning feng shui should be based on choosing a three-in-one comprehensive compass.

The shape of the compass is an inner circle and an outer circle, and the inner disc in the compass can rotate. There must be a 360-degree scale around the inner circle, and there must be two fixed cross longitude and latitude lines on the outer side.

Extended data:

Compass, according to the principles of the Book of Changes and Heluo, and referring to the principles of the sun, the moon, the five stars, the seven strategies and the stars, observes the waves of mountains, rivers and plains on the earth, improves the compass, and is used to determine the orientation and survey the terrain.

Mao on the compass represents the east, noon represents the south, you represents the west, Zi represents the north, Xun represents the southeast, Kun represents the southwest, Gan represents the northwest and Gen represents the northeast.