Projection based advanced motion model for cubic mapping for 360-degree video

TL;DR

This paper introduces a novel motion model for 360-degree video cubic mapping that improves motion handling by projecting pixels back to the sphere, leveraging uniform motion characteristics for better coding efficiency.

Contribution

The paper presents a new advanced motion model that addresses irregular motion in cubic map projections by projecting pixels to the sphere and deriving motion relationships, enhancing coding performance.

Findings

Significant performance improvement for sequences with obvious motions

Effective handling of irregular motion caused by sphere-to-cube projection

Implementation in HEVC software demonstrates practical benefits

Abstract

This paper proposes a novel advanced motion model to handle the irregular motion for the cubic map projection of 360-degree video. Since the irregular motion is mainly caused by the projection from the sphere to the cube map, we first try to project the pixels in both the current picture and reference picture from unfolding cube back to the sphere. Then through utilizing the characteristic that most of the motions in the sphere are uniform, we can derive the relationship between the motion vectors of various pixels in the unfold cube. The proposed advanced motion model is implemented in the High Efficiency Video Coding reference software. Experimental results demonstrate that quite obvious performance improvement can be achieved for the sequences with obvious motions.