The technique of underwater photogrammetry is the reconstruction of submerged scenery from photographs. One of its applications, perhaps the main one, is the investigation of the underwater environment with the intention of interpreting, conserving, disseminating and raising awareness of natural and archaeological heritage. The only equipment needed is a submersible camera and scuba diving equipment.
Another application, beyond underwater archaeology, lies in the possibility of creating with it a model of a thematic scenario, for its construction and subsequent recreation in leisure and tourism facilities. Therefore, thanks to this technique, we can bring spaces from the underwater world to different aquatic facilities, whether in aquariums, animal parks or theme parks, or even hotels and resorts, water parks, campsites, shopping centres and so on. Underwater scenery that is very difficult to access therefore is now available to the general public.
Photogrammetry is a complex process through which three-dimensional information is created, from multiple two-dimensional images taken from alternative viewpoints, using a computer programme that generates point clouds or 3D meshes,. Some of the software available for this are Autodesk ReCap, Agisoft Metashape, AliceVision Meshroom or PIX4D, among others. Unlike LIDAR technology, which uses laser pulses to directly generate point clouds and, with them, create colourless images, photogrammetry compiles data based on what the camera detects with ambient light and, therefore, with colour. In any case, obtaining underwater photogrammetric models involves difficulties due to the refraction of light in the aquatic environment. Two additional problems must be added to these: the depth and possible turbidity of the water.
By Juan Guardiola Cutillas, senior architect in Amusement Logic’s Architecture Department.
