Rapid tunnel scanning using a 360-degree camera and SfM photogrammetry

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openAccess

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A4 Artikkeli konferenssijulkaisussa

Date

2023-01-10

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en

Pages

8

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IOP Conference Series: Earth and Environmental Science, Volume 1124

Abstract

Photogrammetric scanning can be employed for the digitization of underground spaces, for example for remote mapping, visualization, or training purposes. However, such a technique requires capturing many photos, which can be laborious and time-consuming. Previous research has demonstrated that the acquisition time can be reduced by capturing the data with multiple lenses or devices simultaneously. Therefore, this paper demonstrates a method for rapid scanning of hard rock tunnels using Structure-from-Motion (SfM) photogrammetry and a 360-degree camera. The test was performed in the Underground Research Laboratory of Aalto University (URLA). The tunnel is located in granitic rocks at a depth of 20 m below the Otaniemi campus in Espoo, Finland. A 10 m long and 3.5 m high tunnel section with exposed rock was selected for this study. Photos were captured using the 360-degree camera from 27 locations and 3D models were reconstructed using SfM photogrammetry. The accuracy, speed, and resolution of the 3D models were measured and compared with models scanned with a digital single-lens reflex (DSLR) camera. The results show that the data capture process with a 360-degree camera is 6x faster compared to a conventional camera. In addition, the orientation of discontinuities was measured remotely from the 3D model and the digitally obtained values matched the manual compass measurements. Even though the 360-degree camera-based 3D model's quality was visually inferior to the DSLR model, the point cloud had sufficient accuracy and resolution for semi-automatic discontinuity measurements. The quality of the models can be improved by combining 360-degree and DSLR photos which result in a point cloud with 3x higher resolution and 2x higher accuracy. The results demonstrated that 360-degree cameras can be used to rapidly digitize underground tunnels.

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Keywords

photogrammetry, rock mass characterization, tunnel, 360 degree camera system

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Citation

Janiszewski, M, Prittinen, M, Torkan, M & Uotinen, L 2023, ' Rapid tunnel scanning using a 360-degree camera and SfM photogrammetry ', IOP Conference Series: Earth and Environmental Science, vol. 1124, no. 1, 012010 . https://doi.org/10.1088/1755-1315/1124/1/012010