worldframe

The world frame, or world coordinate frame, is a fixed reference coordinate system used to express the positions and orientations of objects within an environment. It provides a common basis for perception, mapping, planning, and visualization across multiple sensors, agents, and time.

Characteristics: The origin and axis directions are defined by the application and are typically chosen to be convenient for the task. The world frame is usually inertial with respect to the environment, meaning it remains stationary while objects move relative to it. In robotics, the world frame is often initialized at the robot's starting pose, and all subsequent poses and landmarks are expressed relative to that frame. Axis conventions vary: some systems use a right-handed system with X forward, Y left, Z up; others may use different orientations.

Transformations: Positions and orientations in the world frame are related to other frames—such as the robot's body frame, sensor frames, or map frame—through rigid body transformations. These are represented by transformation matrices or quaternions, composing rotation and translation. In SLAM and localization, the world frame serves as the global reference against which estimated maps and trajectories are defined; drift and loop closure processes aim to maintain consistency with the world frame.

In computer graphics and simulation, the term world frame (world space) refers to the static coordinate system in which scene geometry is defined before applying camera and object transforms. It contrasts with local or model coordinates and with the camera (view) frame.

Practical considerations: When new environments are encountered, a system may establish a temporary world frame or switch between frames; long-term operations may require re-referencing to a stable world frame to maintain consistency across sessions.