Fig. 1. Flow chart of algorithm

Fig. 2. Interior view of a power plant

Fig. 3. Schematic of octree structure

Fig. 4. Comparison between (a) global fitting and (b) local fitting

Fig. 5. Schematic of plane point cloud filtering based on normal vector constraints

Fig. 6. Schematic of plane filtering and spatial clustering

Fig. 7. Schematic of pipeline data merging

Fig. 8. Virtual scenes in experiment 1. (a) Top view; (b) front view; (c) left view; (d) southeast side view

Fig. 9. Point cloud data in experiment 1

Fig. 10. Sketch after removal of large planes in experiment 1

Fig. 11. Segmentation results of pipeline data in experiment 1. (a) Southeast side view; (b) top view

Fig. 12. Relationship among station locations in experiment 2

Fig. 13. Grayscale image of station Gr01270 in experiment 2

Fig. 14. Sketch of registered point cloud in experiment 2. (a) Left view; (b) southeast side view

Fig. 15. Sketch after removal of large planes in experiment 2. (a) Top view; (b) southeast side view

Fig. 16. Segmentation result of pipeline data in experiment 2. (a) Top view; (b) front view; (c) southeast side view; (d) southwest side view

Fig. 17. Segmentation sketch of pipeline data in experiment 1, where segmented pipeline data are indicated in white domain. (a) Top view; (b) southwest side view

Fig. 18. Segmentation sketch of pipeline data in experiment 2, where segmented pipeline data are indicated in white domain. (a) Top view; (b) southeast side view