Fig. 1. Flowchart of the study
Fig. 2. Line extraction template for vertical lines
Fig. 3. Transmission line point filtering in image space
Fig. 4. Tree-trimming clearance guidelines(Ballard et al., 2007)
Fig. 5. 3D buffering of each transmission line point for near feature detection
Fig. 6. Test area (two spans)
Fig. 7. Generated point cloud (before classification)
Fig. 8. Rasterized elevation model (a)DSM and (b)DTM
Fig. 9. Classified point cloud using height information(red: transmission line, green: non-transmission line, blue: the ground)
Fig. 10. Transmission line extraction using different height thresholds (from left: 10m, 15m, 20m)
Fig. 11. Information loss of transmission lines in raster processing
Fig. 12. Line extraction example (a) drone image (b) morphological opening (c) noise removal
Fig. 13. Transmission line filtering in the image space for different height thresholds (from left: 10m, 15m, 20m)
Fig. 14. Estimated center line of transmission line points(top view)
Fig. 15. Estimated zones along the transmission line (red color, width 27.4m) and border zone(green color, 21.2m from the wire zone)
Fig. 16. 3D buffering for feature detection in security wire zone (simulated) (blue color: transmission line, green: rights-of-way, red: hazardous objects)
Table 1. Minimum vegetation clearance distances for alternating current voltages (meters)
Table 2. Wire height from the ground(Korea Electric Association, 2012)
Table 3. Specification of the drone and camera
References
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