Structure from Motion on a Sphere
This addresses a specialized case in computer vision for applications like 360-degree scene reconstruction, but it is incremental as it builds on existing structure-from-motion frameworks.
The paper tackles the problem of structure from motion for cameras rotating on a sphere, deriving an efficient essential matrix solver that requires only three point correspondences and applying it in a pipeline for scene modeling and object scanning.
We describe a special case of structure from motion where the camera rotates on a sphere. The camera's optical axis lies perpendicular to the sphere's surface. In this case, the camera's pose is minimally represented by three rotation parameters. From analysis of the epipolar geometry we derive a novel and efficient solution for the essential matrix relating two images, requiring only three point correspondences in the minimal case. We apply this solver in a structure-from-motion pipeline that aggregates pairwise relations by rotation averaging followed by bundle adjustment with an inverse depth parameterization. Our methods enable scene modeling with an outward-facing camera and object scanning with an inward-facing camera.