About Project North, True North and Real North

THE THREE NORTH IN BIM.

There are 3 concepts of North in BIM design.

1. Geographic North (Real North) which is the direction to the Earth's North Pole.
2. True North which is the Y direction of the internal (global)  coordinate system.
3. Project North which is the Y direction of the project's local coordinate system.
 

1. Geographic North (Real North)

This is the direction of the Earth's North Pole.

• It is the direction shown by a compass.
• It is tied to the actual location of the project.
• It does not change when you rotate the drawing or the model.

Question: Which way is the real north on the site?
Answer: Geographic North.

2. Project North

This is the north direction chosen by the designer for convenient modeling and documentation.

• It is usually rotated so that the main building walls appear horizontal and vertical on the screen.
• It makes modeling, dimensioning, and documentation easier.
• It does not necessarily match the real north direction.
• This setting simplifies the input of distances using the main directions (X, Y).
  Texts and dimensions are automatically adjusted.

Question: How do I want to see and work on the building on my screen?
Answer: Project North.

3. True North 

This is where most confusion occurs.

Technically, True North represents the Y+ direction of ARCHLine.XP's global coordinate system, which is used as the reference for positioning and orienting the project.

From a user perspective, it can be explained as:

• ARCHLine.XP's own "north" direction.
• The fixed reference direction used by ARCHLine.XP to relate the project to its site orientation.
• Project North is rotated relative to this direction.

Question: What is the fixed north direction that ARCHLine.XP uses to calculate the project's orientation?
Answer: True North.

Display Coordinate Origin Points

The Project North and True North points are visible in floorplan. The active coordinate system is displayed with red-green axes, and the inactive one with gray axes.

True North
Project North