Underwater Optical and Acoustic Imaging: A Time for Fusion? A Brief Overview of the State-of-the-Art

Underwater optical imaging has several drawbacks inherent to the physical medium such as light attenuation and turbidity. Sonars try to obviate those issues although, typically, they have lower resolutions. Combining visual and sonar data in underwater applications is still not popular, but researchers' interest in the topic is growing. However, with the advent of recent higher resolution sonar systems, the approach of combining/fusing information from both sensory modalities can bring improvements to underwater imaging. This has special interest for applications such as autonomous navigation, mapping and object recognition. In this paper we investigate the state of the art for these systems and present the most relevant approaches found in the literature.