Rotation-Invariant Spherical Watermarking via Third-Order SO(3) Representation Coupling

This paper presents a novel method for watermarking panoramic imagery using third-order representations of the rotation group SO(3), addressing the challenges posed by arbitrary 3D rotations. The authors introduce a spherical invariant bispectrum that retains phase information and ensures rotation invariance, allowing for watermark embedding in higher-order spherical harmonic coefficients. This approach demonstrates near-perfect robustness against continuous rotations, which is crucial for practitioners needing reliable watermarking in 3D environments.