Anchor-Based Gravity Alignment for Panoramas

A crucial step for improving the usability of panoramas is the accurate alignment of the upright vector to match the direction of gravity. This paper introduces an anchor-based method for estimating the upright vector in panoramas. Our method, named AnchorsUp, combines the strengths of classification and regression by selecting a rough estimate of the upright vector from a predefined set of anchor vectors, followed by a fine-grained adjustment through regression to achieve precise alignment. We evaluate AnchorsUp on the SUN360 dataset and show superior performance compared to state-of-the-art methods, particularly for angular errors below 5 and 12 degrees, considered the most relevant in practical applications. The source code and dataset information are available at https://github.com/mabergmann/anchorsup.