Putting the compass in front of the door, or under the dripping eaves, or in the center of the house, these sayings of penetrating geomantic omen are no longer applicable in modern geomantic omen, because these places may be disturbed by magnetic fields.
Metal security door, reinforced wall, etc. , it will affect the magnetic needle.
The method I usually use is to set a compass in the room with the largest internal space in the house, such as the living room and dining room near the middle, draw a parallel line with the wall on the ground, or draw a parallel line or vertical line with the door of the house, and measure the angle of this line.
Then the compass must be set up and down on the accurate floor plan of the room to form the following picture, so as to be foolproof.