A geomantic figure half a foot from Lu.

The floor ruler, also known as "quasi-floor ruler", is a measuring tool used in building houses and houses, similar to the bending ruler used by craftsmen today. It is divided into four rows from left to right, which are the traditional four scales of inch, Lu Banchi, Ding Lan ruler and centimeter. Lu Banchi, about 46.08 cm long, is said to have been written by the public transport class of Lu in the Spring and Autumn Period. Later, eight characters were added to the geomantic circle to measure the good or bad of the house, which was called "door plan". Its eight characters are: wealth, illness, divorce, righteousness, official, robbery, harm and capital. Under each word, it is divided into four small words to distinguish between good and bad.