Our research focuses on the problem of path planning in 3D virtual world applications. The characters we consider are heterogeneous, as they have different sizes, and can perform surface or volumetric motion. In this paper, we propose an enhanced waypoint graph, which consists of point nodes equipped with radius, as well as edges connecting those nodes. Each edge is labeled with the motion type it can support. Given a polygon soup representation of a virtual world, the proposed algorithm starts by subdividing the virtual world into regions. This enables us to process large virtual worlds. Each region is then locally voxelized, one at a time. Two kinds of waypoints are generated: local waypoints using corner detection on the voxelization, and border waypoints at the region boundary. Waypoints are then sparsely connected to form a local waypoint graph, and local graphs are finally connected via the border waypoints to create the final global enhanced waypoint graph. To plan paths between arbitrary points using this graph, the points are connected to the graph using nearest neighbor search and traversability test, then Dijkstra/A* algorithm is used to calculate the final path, taking into account the appropriate size and motion type

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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.

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