The large number of bolts and screws that attached to the subway shield ring plates. along with the great amount of accessories of metal stents and electrical equipments mounted on the tunnel walls. make the laser point cloud data include lots of non-tunnel section points (hereinafter referred to as non-points). therefore affecting the accuracy for modeling and deformation monitoring. https://www.roneverhart.com/Western-Digital-Ultrastar-DC-HC550-WUH721816ALE6L0-0F38460-16TB-7-2K-RPM-SATA-6Gb-s-512e-ISE-3-5in-Hard-Drive/