High resolution 3D point clouds and orthomosaics:
Filling the gaps in deep-sea spatial ecology

Within iAtlantic, these new techniques have been used to get a better understanding of the distribution of habitats such as cold-water corals in submarine canyons or hydrothermal vent fauna on a mid-oceanic ridge. In a hydrothermal field off the Azores, a vent chimney has been fully reconstructed in 3D using SfM (see Figure 1, right). Over the years, the technique demonstrates an unexpected stability in the distribution of vent assemblages, which questions the dynamics of hydrothermal vent ecosystems. In submarine canyons, vertical walls have been mapped with a multibeam echosounder mounted on the face of an ROV. The resolution achieved allows individual coral colonies to be distinguished (Figure 2, below). These vertical walls attracted interest of iAtlantic scientists all across the Atlantic, from off Ireland and France to the Azores and Greenland. 3D reconstructions of these walls show how fine scale heterogeneities in the topography and orientation of the walls may influence the distribution of species (see Figure 3, below). These new tools pave the way towards a better view and better understanding of deep seascapes but also pose new challenges. The volume of data is huge. In addition to requiring large computing power, data processing still involves cumbersome image annotations. Within iAtlantic, models based on Artificial Intelligence (AI) have been tested to turn the information contained in images and 3D models into meaningful habitat descriptors.