Investigating submerged morphologies by means of the low-budget “GeoDive” method (high resolution for detailed 3D reconstruction and related measurements)

Abstract

<p class="Abstract">Geophysical methods allow to collect geological data on lakes and seas bottoms and characterize large areas, even at high depths, but with high costs. Moreover, the most widespread acquisition methods for morpho-bathymetric survey and the related instruments used are almost always ship-, ROV- or AUV-based and consequently they require high budgets.</p><p class="Abstract">It is known that shallow waters can represent a limit for certain vessels and techniques, preventing the acquisition in the nearshore zone. To overcome the limits, i.e. to survey with high accuracy nearshore shallow waters with a low budget, we tested and tuned the “GeoDive” method that allowed us to survey two test sites, featured by the presence of “block fields” (i.e., accumulations of huge blocks and boulders of gravitational origin) under shallow waters.</p><p class="Abstract">The “GeoDive” method allowed us to map the submerged morphologies and to acquire high-resolution optical images for further photogrammetric processing. The latter was fundamental to obtain 3D high-resolution models, also with conditions of low visibility. An Action Sport Cam with high definition resolution has been used for video acquisition, in addition to the equipment used during scientific diving.</p><p class="Abstract">By coupling the processing of underwater-acquired data with the direct surveys performed by underwater SCUBA operators, it was possible to perform some morphological and sedimentological measurements and observations on the experimental targets, with the help of suitable markers.</p>

Impact of the October 2018 Storm Vaia on Coastal Boulders in the Northern Adriatic Sea

“…In order to reconstruct the 3D model of the seabed, underwater images were collected via a snorkel survey in June 2019. Photogrammetric procedures are a common and rapid technique to acquire metric measurements in a submarine environment using the combination of field operations and post-processing [31,32]. Submerged photogrammetry requires a precise preparation and setting of the images to reduce water refraction and distortion.…”

Integrating observational targets and instrumental data on rock coasts through snorkel surveys: A methodological approach

“…6), following, for example, the SfM method (Micheletti et al 2015) below the waterline as well (e.g. Gaglianone et al, 2018). Post-processing of images can help refine the mapping of forms, but also to better define the morphometric parameters of coastal landforms through 3D models.…”

Deepwater 3D Measurements with a Novel Sensor System

“…Recent applications have targeted the use of low-cost components in 3D reconstruction in coastal shallow waters using video streams from an action sports camera [27]. Structure-from-motion technology (SfM) was used to create an overall 3D model from the measurements [28].…”