Temporal Correlation Optimization for Accelerated 3D Sparse Convolution in Point Cloud Inference on CPU

3D point clouds primarily consist of irregular, sparse data, dominated by background elements. The inherent irregularity of 3D point clouds induces elevated data movement, while the predominance of background points significantly amplifies computational requirements. Inspired by the substantial overlap of background points in adjacent frames, we introduce a pruning technique that exploits temporal correlations across successive frames to reduce redundant computations and expedite inference. This methodology optimizes computational resources to process valuable and highly correlated data, rather than indiscriminately processing entire point clouds. To further accelerate performance, we enhance data movement using Single Instruction Multiple Data (SIMD) techniques, optimizing the time-intensive Gather and Scatter operations within the dataflow. We compare it with the state-of-the-art sparse inference engine TorchSparse 2.0 to show our proposed method can achieve 1.2× speedup for MinkUnet and SPVCNN, without a significant accuracy loss. In particular, our SIMD-based data movement can achieve more than 5× speedup.