Skeleton-and-Trackball Interactive Rotation Specification for 3D Scenes

We present a new technique for specifying rotations of 3D shapes around axes inferred from the local shape structure, in support of 3D exploration and manipulation tasks. We compute such axes by extracting approximations of the 3D curve skeleton of such shapes using the skeletons of their 2D image silhouettes and depth information present in the Z buffer. Our method allows specifying rotations around parts of arbitrary 3D shapes with a single click, works in real time for large scenes, can be easily added to any OpenGL-based scene viewer, and is simple to implement. We compare our method with classical trackball rotation, both in isolation and in combination, in a controlled user study. Our results show that, when combined with trackball, skeleton-based rotation reduces task completion times and increases user satisfaction, while not introducing additional costs, being thus an interesting addition to the palette of 3D manipulation tools.