nonrotated

Nonrotated is an adjective describing something that has not been rotated relative to a defined reference orientation. It is commonly used in geometry, computer vision, and physics to distinguish objects or frames that maintain a baseline orientation from those that have been rotated.

In geometry and computer vision, a nonrotated object is aligned with the coordinate axes. A nonrotated rectangle, for example, has edges parallel to the x- and y-axes, in contrast to a rotated rectangle. The axis-aligned bounding box (AABB) is a common form of nonrotated bounding box used in collision detection and object localization. If an object's orientation differs from the reference axes, a rotated bounding box or orientation-aware representation is typically used.

In physics and astronomy, "nonrotated" can describe a reference frame that is not undergoing rotation relative to distant stars or another frame. A nonrotating (or inertial) frame can serve as a convenient backdrop for describing motion, whereas a rotating frame requires fictitious forces and additional terms to account for rotation.

Notationally, nonrotation can be formalized by the rotation matrix R being the identity matrix I, implying zero rotation about all axes. In three dimensions, an object is nonrotated if its orientation is given by no rotation, i.e., orientation angle 0 or a quaternion representing identity.

Common related terms include axis-aligned, upright, unrotated bounding box, and rotated bounding box. The choice between nonrotated and rotated representations affects computational efficiency and accuracy in tasks such as object detection, spatial indexing, and kinematics.