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The key challenge in processing point clouds lies in the inherent lack of ordering and irregularity of the 3D points. By relying on per-point multi-layer perceptions (MLPs), most existing point-based approaches only address the first issue yet ignore the second one. Directly convolving kernels with irregular points will result in loss of shape information. This paper introduces a novel point-based bidirectional learning network (BLNet) to analyze irregular 3D points. BLNet optimizes the learning of 3D points through two iterative operations: feature-guided point shifting and feature learning from shifted points, so as to minimise intra-class variances, leading to a more regular distribution. On the other hand, explicitly modeling point positions leads to a new feature encoding with increased structure-awareness. Then, an attention pooling unit selectively combines important features. This bidirectional learning alternately regularizes the point cloud and learns its geometric features, with these two procedures iteratively promoting each other for more effective feature learning. Experiments show that BLNet is able to learn deep point features robustly and efficiently, and outperforms the prior state-of-the-art on multiple challenging tasks.


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BLNet: Bidirectional learning network for point clouds

Show Author's information Wenkai Han1Hai Wu1Chenglu Wen1( )Cheng Wang1Xin Li2
School of Informatics, Xiamen University, 422 Siming South Road, Xiamen 361005, China
School of Electrical Engineering and Computer Science, Louisiana State University, Baton Rouge, LA 70803, USA

Abstract

The key challenge in processing point clouds lies in the inherent lack of ordering and irregularity of the 3D points. By relying on per-point multi-layer perceptions (MLPs), most existing point-based approaches only address the first issue yet ignore the second one. Directly convolving kernels with irregular points will result in loss of shape information. This paper introduces a novel point-based bidirectional learning network (BLNet) to analyze irregular 3D points. BLNet optimizes the learning of 3D points through two iterative operations: feature-guided point shifting and feature learning from shifted points, so as to minimise intra-class variances, leading to a more regular distribution. On the other hand, explicitly modeling point positions leads to a new feature encoding with increased structure-awareness. Then, an attention pooling unit selectively combines important features. This bidirectional learning alternately regularizes the point cloud and learns its geometric features, with these two procedures iteratively promoting each other for more effective feature learning. Experiments show that BLNet is able to learn deep point features robustly and efficiently, and outperforms the prior state-of-the-art on multiple challenging tasks.

Keywords: shape features, point clouds, irregularity, bidirectional learning

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Publication history

Received: 12 March 2021
Accepted: 05 October 2021
Published: 06 March 2022
Issue date: December 2022

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© The Author(s) 2021.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant No. 62171393), and National Key R&D Program of China (Grant No. 2021YFF0704600).

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