基于DenseNet与PointNet融合算法的三维点云分割

3D point cloud segmentation algorithm based on fused DenseNet and PointNet

  • 摘要: 点云分割对于智能驾驶、物体检测和识别、逆向工程等任务非常重要。PointNet是一种能够直接处理点云数据的方法,近年来在点云分割任务中得到广泛应用,但其分割精度较低,而PointNet++的计算成本又较高。针对以上问题,提出一种融合DenseNet和PointNet的算法,用于点云分割,并引入三分支混合注意力机制,以提高PointNet在提取局部特征方面的能力。基于密集连接卷积网络(DenseNet)思想,提出用DenseNet-STN和DenseNet-MLP结构来替代PointNet中的空间变换网络(STN)和多层感知机(MLP);同时,使用Add连接代替密集块(DenseBlock)中的Concat连接,以提高对点特征间相关性的准确性,同时不显著增加模型复杂度。DenseNet-PointNet能够提高复杂分类问题的泛化能力,实现对复杂函数更好的逼近,从而提高点云分割的准确率。有效性和消融实验结果表明,本文算法具有良好的性能。点云分割实验结果表明,DenseNet-PointNet在大多数类别中的交并比(IoU)都高于PointNet的IoU,并在部分类别中也高于PointNet++,参数量是PointNet++的47.6%,浮点运算量(FLOPs)是PointNet++的49.1%。实验结果验证了DenseNet-PointNet的可行性和有效性。

     

    Abstract: Point cloud segmentation is crucial for key tasks, including intelligent driving, object recognition and detection, as well as reverse engineering. PointNet represents a direct point cloud data processing approach widely utilized in point cloud segmentation tasks. Nevertheless, it is associated with low segmentation accuracy and the computational cost of PointNet++ is high. Aiming at the above problems, an algorithm combining DenseNet and PointNet was proposed for the segmentation of point clouds. A three-branch hybrid attention mechanism was introduced to enhance PointNet capability to extract local features. DenseNet-STN and DenseNet-MLP structures were proposed to substitute spatial transformation networks (STNs) and multi-layer perceptrons (MLPs) in PointNet, in line with the dense connected convolutional networks (DenseNet) concept. At the same time, the add connection in DenseBlock, rather than the Concat connection, to enhance the accuracy of point feature correlation, without imposing significant complexity to the model. DenseNet-PointNet demonstrates effective generalization ability for complex classification problems and facilitates better function approximation, thereby improving the precision of point cloud segmentation. The findings of the effectiveness and ablation experiments show that the proposed algorithm performs well. The results of the point cloud segmentation experiments indicate that the intersection and concatenation ratio (IoU) of DenseNet-PointNet is superior to that of PointNet in most categories, and also higher than that of PointNet++ in some categories. DenseNet-PointNet achieves this with only 47.6% of the parameters of PointNet++, and 49.1% of the floating point operations (FLOPs). Therefore, these experimental results confirm the feasibility and availability of DenseNet-PointNet.

     

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