An Alignment Method for the Integration of Underwater 3D Data Captured by a Stereovision System and an Acoustic Camera

Abstract

The integration of underwater 3D data captured by acoustic and optical systems is a promising technique in various applications such as mapping or vehicle navigation. It allows for compensating the drawbacks of the low resolution of acoustic sensors and the limitations of optical sensors in bad visibility conditions. Aligning these data is a challenging problem, as it is hard to make a point-to-point correspondence. This paper presents a multi-sensor registration for the automatic integration of 3D data acquired from a stereovision system and a 3D acoustic camera in close-range acquisition. An appropriate rig has been used in the laboratory tests to determine the relative position between the two sensor frames. The experimental results show that our alignment approach, based on the acquisition of a rig in several poses, can be adopted to estimate the rigid transformation between the two heterogeneous sensors. A first estimation of the unknown geometric transformation is obtained by a registration of the two 3D point clouds, but it ends up to be strongly affected by noise and data dispersion. A robust and optimal estimation is obtained by a statistical processing of the transformations computed for each pose. The effectiveness of the method has been demonstrated in this first experimentation of the proposed 3D opto-acoustic camera.

Real-Time Underwater StereoFusion

“…Fusing inertial with vision-based navigation will improve both the estimation quality and the system’s robustness. Additionally, the system can be made more robust to low visibility by using a 3D sonar, either instead of the stereo camera, or by fusing the acoustic with vision data in a manner similar to that described by [ 36 ]. Ongoing testing will provide information on the quality of a 3D sonar used as the only sensor, using the same algorithm described in this paper.…”

“…Most sonars are however not suitable for high precision close range applications due to their low resolution and relatively high minimum operating range. A hybrid vision-acoustic approach has been proposed by [ 36 ] using a high-end commercial 3D sonar, which aims to provide the robustness of sonars with the colour information and accuracy of cameras. Such a sonar could be used on its own in a similar way to a depth camera, except for the absence of colour information.…”

Underwater augmented reality for improving the diving experience in submerged archaeological sites

“…The use scenario to which the UWAR technology developed in the iMARECulture project is intended consists in providing to the divers the possibility to know their position within the submerged environment and to enable the augmented visualization of the actual conditions of the ancient ruins in the underwater site and a hypothetical reconstruction of the villa, thus easily understanding the luxury and the importance of that building during the Roman era. The starting point for preparing the 3D data and contents that are necessary for the functioning of the proposed UWAR technologies consists of the 3D reconstruction of the abovementioned archaeological area that has been carried out by combining optical and acoustic techniques [Lagudi et al 2016;Mangeruga et al 2018]. The 3D reconstruction model is then populated with a number of points of interest (POIs), placed on the seafloor, which provide the position of the distinctive and characteristic element of the specific underwater site.…”

3D Room Geometry Reconstruction Using Audio-Visual Sensors

“…Murino and Fusiello used sonar and camera to model underwater scenes [24]. Lagudi et al proposed alignment method for the integration of stereo cameras and an acoustic camera for underwater 3D data capture [22]. Recently Ye at al.…”