Abstract: A computer system displays a representation of a field of view of the one or more cameras, including a representation of a portion of a three-dimensional physical environment that is in the field of view of the one or more cameras. The computer system receives a request to add a first virtual effect to the displayed representation of the field of view of the one or more cameras. In response to receiving the request to add the first virtual effect to the displayed representation of the field of view of the one or more cameras and in accordance with a determination that the first virtual effect requires a scan of the physical environment, the computer system initiates a scan of the physical environment to detect one or more features of the physical environment and displays a user interface that indicates a progress of the scan of the physical environment.

Abstract: An optical element (10) is pivoted for limited rotation about an axis (12). An actuator arm (14) is rotatable by an actuator (13) about an axis (15) and is connected to the optical element by a first link (16). A second link (21) connects the actuator arm (14) to a balance arm (18) which carries a balance mass (20) and is pivoted about an axis (19). The arrangement is such that the line (23) joining the axis (12) of the optical element to the point of connection between the first link (16) and the optical element (10) is always parallel to the line (24) joining the axis (19) of the balance arm (18) to the point of connection between the balance arm and the second link (21).