Conditional Directed Graph Convolution for 3D Human Pose Estimation

16 Jul 2021  ·  WenBo Hu, Changgong Zhang, Fangneng Zhan, Lei Zhang, Tien-Tsin Wong ·

Graph convolutional networks have significantly improved 3D human pose estimation by representing the human skeleton as an undirected graph. However, this representation fails to reflect the articulated characteristic of human skeletons as the hierarchical orders among the joints are not explicitly presented. In this paper, we propose to represent the human skeleton as a directed graph with the joints as nodes and bones as edges that are directed from parent joints to child joints. By so doing, the directions of edges can explicitly reflect the hierarchical relationships among the nodes. Based on this representation, we further propose a spatial-temporal conditional directed graph convolution to leverage varying non-local dependence for different poses by conditioning the graph topology on input poses. Altogether, we form a U-shaped network, named U-shaped Conditional Directed Graph Convolutional Network, for 3D human pose estimation from monocular videos. To evaluate the effectiveness of our method, we conducted extensive experiments on two challenging large-scale benchmarks: Human3.6M and MPI-INF-3DHP. Both quantitative and qualitative results show that our method achieves top performance. Also, ablation studies show that directed graphs can better exploit the hierarchy of articulated human skeletons than undirected graphs, and the conditional connections can yield adaptive graph topologies for different poses.

PDF Abstract
Task Dataset Model Metric Name Metric Value Global Rank Benchmark
3D Human Pose Estimation Human3.6M U-CondDGConv@GT_2D_Pose Average MPJPE (mm) 22.7 # 9
Using 2D ground-truth joints Yes # 1
Multi-View or Monocular Monocular # 1
3D Human Pose Estimation Human3.6M U-CondDGConv Average MPJPE (mm) 41.1 # 64
Using 2D ground-truth joints No # 1
Multi-View or Monocular Monocular # 1
3D Human Pose Estimation MPI-INF-3DHP U-CondDGConv AUC 69.5 # 5
MPJPE 42.5 # 4
PCK 97.9 # 2