Reference

How to understand 3D coordinates in the scene

For a 3D coordinate system, the scene’s origin is at (0,0,0). We can represent the position of any role as a certain number of units to the left or right of the origin, a certain number of units above or below the origin, and a certain number of units in front of or behind the origin. These three dimensions are known as the X-axis, Y-axis, and Z-axis.

These three numbers provide the 3D coordinates of a point in space. For example, a point located 7 units to the right of the origin (X-axis), 3 units above the origin (Y-axis), and 4 units in front of the origin (Z-axis) has the （x, y, z） coordinates of (7,3,4). To specify a point in the opposite direction of the origin, we should use negative numbers. For instance, a point located at (-5, -2, -1) is 5 units to the left of the origin, 2 units belove the origin, and 1 unit behind the origin.