Fiducial Marker Detection in Multi-Viewpoint Point Cloud
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The existing LiDAR fiducial marker systems have usage restrictions. Especially, LiDARTag requires a specific marker placement and Intensity Image-based LiDAR Fiducial Marker demands that the point cloud is sampled from one viewpoint. As a result, with point clouds sampled from multiple viewpoints, fiducial marker detection remains an unsolved problem. In this letter, we develop a novel algorithm to detect the fiducial markers in the multi-viewpoint point cloud. The proposed algorithm includes two stages. First, Regions of Interest (ROIs) detection finds point clusters that could contain fiducial markers. Specifically, a method extracting the ROIs from the intensity perspective is introduced on account of the fact that from the spatial perspective, the markers, which are sheets of paper or thin boards, are non-distinguishable from the planes to which they are attached. Second, marker detection verifies if the candidate ROIs contain fiducial markers and outputs the ID numbers and vertices locations of the markers in the valid ROIs. In particular, the ROIs are transmitted to a predefined intermediate plane for the purpose of adopting a spherical projection to generate the intensity image, and then, marker detection is completed through the intensity image. Qualitative and quantitative experimental results are provided to validate the proposed algorithm. The codes and results are available at: https://github.com/York-SDCNLab/Marker?Detection-General
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