No abstract

In this work, we improved the efficiency and accuracy of our proposed cylinder-based registration and model fitting method of point clouds by terrestrial laser scanners for the as-built modeling of piping systems. Our algorithm simultaneously calculated the scanner parameters and cylinder parameters to avoid the propagation of registration errors and modeling errors. Coarse registration is performed by finding the alignment of the cylinder axes based on the random sample consensus approach and using a hash table. The efficiency of the coarse registration is improved by introducing a three-dimensional hash table. The fine registration and modeling is performed by minimizing the fitting errors of the cylinders as a nonlinear function of the positional and geometric parameters of scanners and cylinders. An iteratively reweighted least squares method is applied to the fine registration and modeling, leading to improved robustness. Moreover, for the modeling of pipes that are slightly bent due to gravity, incident angle filtering of scanned points and cylinder subdivision of the pipes to be modeled are introduced. The efficiency and robustness of the improved algorithm were compared with the previous approach using both artificial and real point clouds. The effectiveness of incident angle filtering and cylinder subdivision was confirmed. The proposed algorithm achieved the level of cylindrical modeling precision required for the renovation work of piping systems.

No abstract

Extracting wireframes from 3D meshes is a challenging problem. Existing methods are typically based on analyzing local shape properties, such as surface curvatures and angles between faces, which are generally sensitive to small features in the model and the complexity of the object. In this work, we propose a wireframe extraction method based on a geometric approximation of 3D meshes. Our idea is to utilize a well-established variational geometric partitioning method to derive a complete set of descriptive feature curves. The advantage of this strategy is that a reliable feature ltering mechanism can be inherently incorporated into the geometric approximation step, giving rise to descriptive wireframes that capture global structures of the 3D meshes. We experimented on various meshes. The results demonstrated that our method is superior to existing approaches in terms of the correctness and completeness of the extracted feature curves.