A paper by Verena Vogler,  original link here.

 

This paper introduces new methods and techniques for artificial coral reef design and fabrication based on the Biorock(c) Technology to enable regrowth of damaged coral reefs and discusses state- of- the- art underwater monitoring methods to 3-D reconstruct point cloud models of high precision of our Artificial Reef Prototype (ARP) located in Gili Trawangan, Indonesia. ARP is made out of 200 lightweight construction elements that can be assembled underwater by one diver. Therefore, no boat has to transport the artificial reef structure to the implementation site. ARP is extendable, adapts to the topography of the seafloor and resisted strong storms and an earthquake of 6.9 in August 2018. It works as Biorock reef with a grown calcium carbonate layer of 1.5- 3.00 cm around the construction elements after five years of being in the sea.

To better understand growth procedures and the intricate surface configurations of ARP, we used different 3-D scan methods, including LiDAR scanning (M210UW Newton Labs underwater laser scanner), and high-resolution underwater photogrammetry (Sony Cyber-shot RX100 II, Canon EOS 5Ds) and a CT Scan. In our contribution, we present a) the overall approach and the chosen case study, b) the specific workflow to survey marine environments with millimeter precision, and c) a comparison between different 3-D scan methods applied in this context. Against this background, we discuss the applicability of both methods and their viability for voxel models from high-resolution computed tomography (CT) scans of an extracted sample of ARP.

 

Reference (Chicago): Vogler, Verena, Sven Schneider, and Jan Willmann. n.d. “High-Resolution Underwater 3-D Monitoring Methods to Reconstruct Artificial Coral Reefs in the Bali Sea: A Case Study of an Artificial Reef Prototype in Gili Trawangan.” In Journal of Digital Landscape Architecture, 275–89. doi:10.14627/537663030.