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计算机工程 ›› 2023, Vol. 49 ›› Issue (10): 247-254. doi: 10.19678/j.issn.1000-3428.0065825

• 图形图像处理 • 上一篇    下一篇

改进特征匹配的ORB-SLAM稠密建图算法

刘洋1, 陈俊1, 胡诗佳1, 赖佳华2   

  1. 1. 福州大学 先进制造学院, 福建 晋江 362200
    2. 中国科学院海西研究院泉州装备制造研究中心, 福建 晋江 362200
  • 收稿日期:2022-09-22 出版日期:2023-10-15 发布日期:2023-10-10
  • 作者简介:

    刘洋(1996-), 男, 硕士研究生, 主研方向为视觉SLAM

    陈俊, 副教授、硕士

    胡诗佳, 硕士研究生

    赖佳华, 硕士研究生

  • 基金资助:
    国家自然科学基金(61871132)

Improved Feature Matching ORB-SLAM Algorithm for Dense Mapping

Yang LIU1, Jun CHEN1, Shijia HU1, Jiahua LAI2   

  1. 1. School of Advanced Manufacturing, Fuzhou University, Jinjiang 362200, Fujian, China
    2. Quanzhou Institute of Equipment Manufacturing Haixi Institutes, Chinese Academy of Sciences, Jinjiang 362200, Fujian, China
  • Received:2022-09-22 Online:2023-10-15 Published:2023-10-10

摘要:

对于同步定位与建图(SLAM)中主流的特征点法,特征匹配是估计相机运动的关键,然而在特征匹配过程中存在图像特征的局部特性、误匹配等问题,成为视觉SLAM的瓶颈。此外,特征点法生成的稀疏地图只能用于定位,无法满足更高层次的需求。针对ORB-SLAM3中ORB特征点匹配效率低且未能生成稠密地图的问题,提出一种改进的ORB-GMS匹配策略并在ORB-SLAM3系统中加入稠密点云构建线程来实现稠密建图。将运动平滑性约束作为特征点运动统计的方法,通过比较特征点邻域内的匹配数量和阈值快速判断当前匹配是否正确,将图片网格化并快速计算网格内特征点的匹配数量,进行相机的位姿估计。根据关键帧与相应位姿构建稠密点云地图,采用外点去除滤波和体素网格滤波减小点云规模。在TUM的RGB-D数据集上的实验结果表明,与ORB-SLAM3相比,该算法可以减少约50%的匹配耗时,同时在匹配数量上平均提升60%,定位平均误差降低32%。此外,与稀疏地图相比,该方法生成易于2次加工的稠密点云地图,扩大算法的应用场景。

关键词: 同步定位与建图, 特征点, 特征匹配, 基于网格的运动统计, 稠密建图, 点云滤波

Abstract:

In the mainstream feature-based Simultaneous Localization and Mapping(SLAM) method, feature matching is a key step in estimating camera motion. However, the local characteristics of image features cause widespread mismatch and have become a major bottleneck in visual SLAM. In addition, the sparse maps generated by the feature-based method can only be used for localization, as they do not satisfy higher-level requirements. To address the problems of low efficiency in ORB feature point matching and failure to generate dense maps in ORB-SLAM3, an improved ORB Grid-based Motion Statistics(ORB-GMS) matching strategy is proposed, whereby a dense point cloud construction thread is added to ORB-SLAM3 to realize dense mapping. The motion smoothness constraint is used for the feature point motion statistics method, and the number of matches in the feature point neighborhood and threshold are compared to efficiently determine whether the current match is correct. The gridded images are used for fast computation to perform camera pose estimation. Finally, the dense point cloud map is constructed according to the key frame and the corresponding pose, using the outlier point removal and voxel-grid filters to reduce the size of the point cloud. The experimental results on the RGB-D dataset of TUM show that compared with ORB-SLAM3, the proposed algorithm can reduce matching time by approximately 50% and average positioning error by 32%, while increasing the number of matches by an average of 60%. In addition, compared to sparse maps, this method generates dense point cloud maps that are easy for secondary processing, thereby expanding the application scenarios of the algorithm.

Key words: Simultaneous Localization and Mapping(SLAM), feature point, feature matching, Grid-based Motion Statistics(GMS), dense mapping, point cloud filter