Extend gravity-aware feature-based pose estimation to the no-IMU setting

Investigate whether the affine- and orientation-covariant feature-based absolute pose estimation framework can be applied when no gravity direction is known, and determine whether such an extension is sufficiently interesting and protectable to warrant development.

Background

The paper develops minimal solvers for upright absolute pose estimation with unknown focal length by exploiting a known gravity direction, typically obtained from an inertial measurement unit. In the supplementary material, the authors briefly note that the approach could potentially be generalized to the case in which no gravity direction is available.

This extension is not developed, analyzed, or experimentally evaluated. The authors explicitly express uncertainty about whether the no-IMU version is sufficiently interesting and protectable, leaving its practical and research value unresolved.