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Journal of Zhejiang University (Science Edition)  2023, Vol. 50 Issue (6): 770-780    DOI: 10.3785/j.issn.1008-9497.2023.06.012
CSIAM-GDC 2023     
A point cloud processing network combining global and local information
Yujie LIU,Yafu YUAN(),Xiaorui SUN,Zongmin LI
College of Computer Science and Technology,China University of Petroleum,Qingdao 266580,Shandong Province,China
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Abstract  

To address the limitations of current mainstream networks, which rely solely on local neighborhoods for feature aggregation and suffering from insufficient feature extraction capabilities and information loss due to max-pooling, we propose an attention-based point cloud processing network that combines both local and global information. First, we introduce channel attention for local feature aggregation to minimize information loss. Next, we design a dynamic key point learning method to capture the remote dependency information of points and obtain global information. Finally, we develop a spatial attention fusion module to allow each point to learn the global con-textual information. Our proposed method has been benchmarked on several point cloud analysis tasks. It achieved an overall classification accuracy of 94.0% and an average classification accuracy of 91.7% on the ModelNet40 classification task. On the ScanObjectNN classification task, our method reached an overall class fication accuracy of 81.5% and an average classification accuracy of 78.1%. In the ShapeNet segmentation task, we obtained a mean intersection over union of 86.5%. The experimental results show that the proposed network has significantly improved accuracy compared to classical networks such as PointNet, PointNet++, and DGCNN in classification and segmentation tasks, and has also achieved improvement in deferent degree compared to other point cloud processing networks.



Key wordspoint cloud classification      point cloud segmentation      attention mechanism      global information      local information     
Received: 21 June 2023      Published: 30 November 2023
CLC:  TP 391.41  
Corresponding Authors: Yafu YUAN     E-mail: yuanyafu@s.upc.edu.cn
Cite this article:

Yujie LIU,Yafu YUAN,Xiaorui SUN,Zongmin LI. A point cloud processing network combining global and local information. Journal of Zhejiang University (Science Edition), 2023, 50(6): 770-780.

URL:

https://www.zjujournals.com/sci/EN/Y2023/V50/I6/770


局部信息和全局信息相结合的点云处理网络

针对当前主流点云处理网络仅依靠局部邻域进行特征聚合导致特征提取能力不足,以及使用最大值池化造成信息损失的问题,提出了一种基于注意力的局部信息和全局信息相结合的点云处理网络。首先提出了基于通道自注意力进行局部特征聚合的方法,减少了信息的损失;然后为捕获点的远程依赖信息,设计了一种动态学习关键点的方法获取全局信息; 最后构建了一种基于空间注意力的特征融合模块,使每个点均能学习全局上下文信息。在几个常用点云数据集上对方法进行了实验验证,在ModelNet40分类任务上实现了94.0%的总体分类精度、91.7%的平均分类精度;在ScanObjectNN分类任务上实现了81.5%的总体分类精度、78.1%的平均分类精度;在ShapeNet 分割任务上实现了86.5%的平均交并比。表明提出的点云处理网络在分类、分割等任务中的精度均较PointNet、PointNet++、DGCNN等经典网络有显著提升,较其他点云处理网络也有不同程度的提高。


关键词: 点云分类,  点云分割,  注意力机制,  全局信息,  局部信息 
Fig.1 Three feature aggregation methods
Fig.2 A and B two-point spatial diagram and neighborhood plane schematic
Fig.3 The feature aggregation process of mainstream methods
Fig.4 Local information aggregation module based on channel self-attention
Fig.5 Feature fusion module based on spatial attention
Fig. 6 LGA module
Fig. 7 LGANet
方法MA/%OA/%
PointNet186.089.2
PointNet++2-90.7
PointCNN[1088.192.3
A-CNN490.392.6
DGCNN1790.292.9
PAConv12-93.6
PointASNL22-92.9
GDANet23-93.4
CurveNet25-93.8
Point Trans1890.693.7
PointMLP4491.394.1
PointNeXt45-94.0
LGANet91.794.0
Table 1 The accuracy of different methods on ModelNet40 dataset
方法MA/%OA/%
PointNet163.268.2
PointNet++275.477.9
DGCNN1773.678.1
SpiderCNN1169.873.7
PointCNN1075.178.5
DRNet4278.080.3
GBNet4377.880.5
LGANet78.181.5
Table 2 The accuracy of different methods on ScanObjectNN dataset
类别mIoU/%
PointNet1PointNet++2DGCNN17SpiderCNN11PointASNL22GS-Net21PointCNN10LGANet
飞机83.482.484.083.584.182.984.185.1
书包78.779.083.481.084.784.386.585.1
帽子82.587.786.787.287.988.686.090.1
汽车74.977.377.877.579.778.480.880.0
椅子89.690.390.690.792.289.790.691.6
耳机73.076.874.776.873.778.379.777.6
吉他91.591.091.291.191.091.792.392.0
85.985.987.587.387.286.788.487.8
80.883.782.883.384.281.285.385.3
电脑95.395.395.795.895.895.696.196.1
摩托65.271.666.370.274.472.877.273.2
杯子93.094.194.993.595.294.795.295.5
手枪81.281.381.182.781.093.184.281.6
火箭57.958.763.559.763.062.364.259.0
滑板72.876.474.575.876.381.580.077.0
桌子80.682.682.682.883.283.883.083.9
整体83.785.185.285.386.185.386.186.5
Table 3 Comparison of mIoU by category and overall ShapeNet part
Fig.8 Visualization of the segmented results of the ShapeNet dataset
模型模块OA/%
LIACA-1LIACA-2DLKSAFA
A92.5
B??93.0
C????93.3
D??????93.7
E????92.9
F????????94.0
Table 4 Ablation experiments
策略OA/%
FPS93.1
Random92.7
DLK94.0
Table 5 OA of key selection strategies
关键点数OA/%
093.3
25692.9
50094.0
1 02493.4
Table 6 OA of different number of key points
方法参数量/MOA/%
PointNet13.5089.2
PointNet++21.4890.7
GS-Net211.5192.9
GBNet438.3993.8
LGANet2.2094.0
Table 7 Comparison of complexity of classification models
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