坐标系

Understand the UCS in 3D

When you create or modify objects in a 3D environment,
you can move and reorient the UCS anywhere in 3D space to simplify your work.
The UCS is useful for entering coordinates, creating 3D objects on 2D work planes, and rotating objects in 3D.
The UCS icon changes automatically depending on the current visual style.
The colorful 3D icon on the right displays when a 3D visual style is current.

Note: The UCS icon follows the traditional right-hand rule in determining positive axis directions and rotation directions.

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