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PointConvFormer: Revenge of the Point-Based Convolution (arxiv.org)
1 point by PaulHoule on Aug 8, 2022 | hide | past | pdf | discuss on HN

In plain words: A new building block for 3D point clouds blends position-based convolution with attention that compares neighbors' features to pick the useful ones. It offered a better accuracy-speed balance than classic convolutions, attention-only networks, and cube-chopping methods on segmentation and scene flow.

Abstract · PointConvFormer: Revenge of the Point-based Convolution

We introduce PointConvFormer, a novel building block for point cloud based deep network architectures. Inspired by generalization theory, PointConvFormer combines ideas from point convolution, where filter weights are only based on relative position, and Transformers which utilize feature-based attention. In PointConvFormer, attention computed from feature difference between points in the neighborhood is used to modify the convolutional weights at each point. Hence, we preserved the invariances from point convolution, whereas attention helps to select relevant points in the neighborhood for convolution. PointConvFormer is suitable for multiple tasks that require details at the point level, such as segmentation and scene flow estimation tasks. We experiment on both tasks with multiple datasets including ScanNet, SemanticKitti, FlyingThings3D and KITTI. Our results show that PointConvFormer offers a better accuracy-speed tradeoff than classic convolutions, regular transformers, and voxelized sparse convolution approaches. Visualizations show that PointConvFormer performs similarly to convolution on flat areas, whereas the neighborhood selection effect is stronger on object boundaries, showing that it has got the best of both worlds.

Wenxuan Wu, Li Fuxin, Qi Shan
arXiv:2208.02879 · cs.CV, cs.LG · submitted Aug 4, 2022 · updated May 10, 2023
abstract · pdf · html · Accepted at CVPR 2023

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