A viewpoint planning strategy for determining true angles on polyhedral objects by camera alignment

The paper presents a viewpoint planning strategy which automatically guides a movable camera from an arbitrary position to a position where the optical axis is perpendicular to a plane spanned by any two intersecting edges on a polyhedral object, i.e., a junction. In related work it is common to use the changing length of edge segments to control such alignment, but we demonstrate the use of the apparent angle between the edge segments of the junction. Based on the control on the apparent angle we achieve robustness as well as independence of distance to the object and focal length. The strategy is able to determine the true angle of a junction with an accuracy of approximately 1°, and align with an accuracy of approximately 6°