建筑物几何约束的航空影像与机载LiDAR点云配准

Registration of Aerial Imagery with Airborne LiDAR Point Clouds Using Building Geometric Constraints

  • 摘要: 航空影像与机载激光雷达(Light Detection and Ranging,LiDAR)点云的高精度融合依赖二者的精确配准,但现有方法面临双重挑战:对初始位姿偏差敏感,且难以可靠提取跨模态、跨维度的同名特征,制约了融合效果。为此,本研究提出一种建筑物全局与局部特征约束的航空影像与机载LiDAR点云直接配准方法。首先,分别从航空影像生成的稀疏点云和机载LiDAR点云中提取建筑物实例。利用其全局几何分布的相似性,通过图匹配网络实现粗配准。其次,分别从影像和LiDAR点云提取建筑物轮廓线段,基于空间几何一致性进行线段匹配。最后,构建优化函数最小化匹配线段间的欧氏距离,结合随机一致性(Random Sample Consensus,RANSAC)求解最优影像外参。在两个不同场景数据集上的实验表明,该方法实现了航空影像与机载LiDAR的高精度配准,平均投影误差分别低至0.26倍和0.5倍点云平均间距。

     

    Abstract: Objectives: Significant initial deviations in the Exterior Orientation Parameters (EOPs) between aerial imagery and Airborne Light Detection and Ranging (LiDAR) data often lead to insufficient registration accuracy, adversely affecting the fusion of multi-source geospatial data. To overcome this challenge, a registration method is proposed that integrates both global distribution and local contour features of buildings. The primary goal is to substantially enhance the fusion accuracy of these two data types, thereby providing a reliable foundation for critical applications such as high-precision change detection, refined feature extraction, and high-fidelity 3D real-scene modeling. Methods: The methodology comprises three key stages. First, in the global coarse registration stage, Structure from Motion (SfM) technology is used to reconstruct a sparse 3D point cloud from overlapping aerial image sequences. Subsequently, through efficient filtering and Euclidean clustering algorithms, individual building instances are segmented and extracted from the image-derived sparse point cloud and the LiDAR point cloud, respectively. Given the relatively stable global layout characteristics of buildings in urban spaces, a deep learning-based Graph Matching Network (GMN) is introduced to abstract the scattered building instances into graph nodes. By learning and comparing the topological similarity of their spatial distribution relationships, cross-source building instance-level correspondences are established, thereby effectively correcting large-scale rotation and translation deviations. Second, in the local fine registration stage, we shift our focus to the geometric details of the buildings themselves. Building contour line segments are accurately extracted from aerial images and the LiDAR point cloud, respectively. On this basis, rigorous screening and matching are performed using multiple geometric constraints, including directional consistency, length similarity, and spatial proximity between line segments, to construct a set of high-confidence corresponding line segment pairs. Finally, based on the above reliable matching primitives, an overall optimization function is constructed with the objective of minimizing the cumulative spatial Euclidean distance between all corresponding line segment pairs. To enhance the robustness of the algorithm, the Random Sample Consensus (RANSAC) algorithm is integrated during the optimization process to solve for the optimal aerial image EOPs. This iterative approach identifies and eliminates potential mismatches, ensuring the accuracy and stability of the solution. Results: To validate the effectiveness and universality of the proposed method, experiments were conducted on two datasets with different point cloud densities and different image resolutions. Quantitative analysis results demonstrate that after registration using the proposed method, the average projection errors on the two datasets were significantly reduced to 0.26 times and 0.5 times the average point spacing of their corresponding LiDAR point clouds, respectively. This accuracy significantly outperforms traditional registration methods based on single features, proving the excellent performance of our method across different data specifications. Conclusions: The synergistic optimization mechanism integrating global distribution constraints and local line feature matching effectively overcomes modal transformation errors and initial extrinsic parameter deviations, establishing a high-precision registration foundation for multi-source geospatial data fusion.

     

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