深度上下文动态点云几何压缩
Deep Contextual Dynamic Point Cloud Geometry Compression
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摘要: 现有的动态点云压缩方法采用预测编码的框架, 通过对当前帧点云进行预测计算预测帧与当前帧的残差并进行编码, 但由于使用残差编码消除帧间冗余, 在运动比较剧烈和内容细节丰富的区域压缩效果欠佳. 针对此缺陷, 使用条件编码替代传统的预测编码, 提出一个基于条件编码的深度上下文动态点云几何压缩方法. 首先构建一个特征空间多尺度场景流网络,用于计算动态点云的运动向量, 以提高运动估计的精度; 然后通过上下文生成模块构造上下文信息, 并且直接以此信息为条件对当前帧点云进行编码和解码; 最后融合时间先验与超先验信息, 设计一个基于上下文信息的熵模型, 用于估计点云的条件概率分布, 提高熵编码效率. 以率失真曲线的BD-rate作为性能指标, 与D-dpcc相比, 在8iVFB数据集上, 所提方法的平均比特率降低13.62%; 在MVUB数据集上, 该方法的平均比特率降低15.15%; 压缩性能得到显著提升.Abstract: Existing dynamic point cloud compression methods adopt a predictive coding framework, where the residual between a predicted frame and the current frame is calculated and encoded based on the prediction of the current frame's point cloud. However, due to the use of residual coding to eliminate inter-frame redundancy, the compression performance in regions with intense motion and rich content details is subpar. To address this limitation, this paper proposes a depth context-based dynamic point cloud geometry compression method using conditional coding instead of traditional predictive coding. Firstly, a feature space multi-scale scene flow network is constructed to calculate the motion vectors of the dynamic point cloud, enhancing the accuracy of motion estimation. Secondly, a context generation module is utilized to construct context information, which is then directly used as a condition for encoding and decoding the current frame's point cloud. Lastly, by fusing temporal priors with hyperpriors, a context-based entropy model is designed to estimate the conditional probability distribution of the point cloud, thereby improving the efficiency of entropy coding. Evaluated using the BD-rate of rate-distortion curves as the performance metric, the proposed method achieves an average bitrate reduction of 13.62% compared to D-dpcc on the 8iVFB dataset and 15.15% on the MVUB dataset, significantly enhancing compression performance.