In November 2015, a team from University of Otago, New Zealand, was performing a pilot survey of an underground network of tunnels used during World War I, in Arras, north of France.
The project, called LiDARRAS, is done in partnership with different New Zealand and French institutions, schools and private partners including Trimble.
Goal of this first week of 3D scanning and underground control network establishment was to understand all specific aspects of this very unsual job.
A full Trimble scanning solution has been provided to the team during this pilot survey: Trimble TX8, panoramic camera kit, Trimble RealWorks, Trimble ScanExplorer.
The team will go back in Q3 2016 for a month to complete this impressive historical project.
Pictures from the pilot survey:
Here is a feedback from Pascal Sirguey, senior lecturer at the University of Otago and leader of the LiDARRAs project:
I am delighted to report that the LiDARRAS pilot survey was highly successful.
Over nearly three weeks, Richard Hemi and surveying student Chris Page completed over 100 scans in the Carriere Wellington. They mostly used the Trimble TX8 scanner kindly borrowed by Gregory Lepere from TRIMBLE. It turned out that the use of portable light sources along with the high quality panoramic camera setting associated with the TX8 yielded enough quality to colorize the point clouds.
The area scanned included nearly all the public path in the Wellington quarry (see below) as well as the tunnel access to the Auckland quarry.
Further to this, a network of marks was set up in the quarry for a convenient triangulation of ground control marks. The network absolute coordinates were obtained by a traverse from the emergency exit at the south of Auckland quarry to the emergency exit in the Wellington quarry. This task was completed by the surveying crew of ESGT (student and staff) who reported a closure accuracy of about 2cm. This is quite satisfying given the underground situation. ESGT students also acquired their own scans with a Leica C10.
Gregory Lepere who assisted our crew at the start of the project was kind enough to put together a quick animation of the first few scans assembled, giving some idea of what we aim to achieve. The animation is available at https://youtu.be/1xT8yYTaeNA
This pilot survey allowed us to address a lot of question marks we had about the structure and how to approach the scanning in this challenging situation. It has enabled us to acquire enough experience of the terrain to foresee a successful survey in Q3 2016. At this stage, Chris Page and a student from the ESGT will have 3-4 weeks to tackle the rest of the Wellington Quarry, as well as the Blenheim and the Nelson quarries (see below).
We thank again all our sponsors, organisations, and individuals who made this project possible with funding from the Lottery World War One Commemorations, Environment and Heritage Committee, the New Zealand France Friendship Fund, and the Fondation de France.
Stay tuned for more update on the LiDARRAS project.