# Deepwater 3D Measurements with a Novel Sensor System
); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] or [EMAIL_ADDRESS] (G.N.) [PERSON] and [PERSON]  
1 Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, D-07745 Jena, Germany; [EMAIL_ADDRESS] (C.M. ); [PERSON]] (M.H. ); [EMAIL_ADDRESS] (I.G. ); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] or [EMAIL_ADDRESS] (G.N.) [PERSON] and [PERSON]  
1 Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, D-07745 Jena, Germany; [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (I.G. ); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] or [EMAIL_ADDRESS] (G.N.) [PERSON] and [PERSON]  
1 Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, D-07745 Jena, Germany; [EMAIL_ADDRESS] (C.M. ); [PERSON]] (M.H. ); [EMAIL_ADDRESS] (I.G. ); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] or [EMAIL_ADDRESS] (G.N.) [PERSON] and [PERSON]  
1 Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, D-07745 Jena, Germany; [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (I.G. ); [EMAIL_ADDRESS] (P.K. ); [EMAIL_ADDRESS] or [EMAIL_ADDRESS] (G.N.) 2 Robotics and [PERSON]  
1 Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, D-07745 Jena, Germany; [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (I.G. ); peter.kuehnstedtwind foundations, pipeline systems for oil and gas transport, and cable or anchor chain inspections. For these purposes, new 3D measurement systems with improved features and easier handling are currently being developed. Various non-contact methods are available for 3D reconstruction underwater, e.g., techniques with sonar systems [1; 2; 3], laser scanning [4], time-of-flight measurements (ToFs) [5; 6], and photogrammetry [7; 8; 9; 10]. Optical time-of-flight (ToF) sensors, which are based on the temporal evaluation of light pulses, provide similar accuracy to acoustic systems for 3D underwater measurements. These systems, based on LiDAR technology, are available, for example, from the company 3D at Depth [5]. [PERSON] et al. [6] present a new ToF-based measurement system called UTOFIA. Laser scanner systems are suitable for obtaining 3D data underwater and addressing the challenges posed by long distances and cloudy water [11; 12; 13]. These measurements can also be carried out in motion and offer a high level of robustness. As a rule, laser systems are based on the capture of individual lines, which must be merged into a 3D scan. Visual odometry is used to estimate vehicle navigation and motion data [14]. Generated motion data are used, for example, for the 3D mapping of the route traveled, but has a much lower accuracy than measurement data obtained from photogrammetry. Underwater photogrammetry has been used for decades for the highly accurate reconstruction of objects such as shipwcks [7; 8]. However, a lot of preparation work is required to achieve a high level of measurement accuracy. This concerns the placement of markers and textured objects or the support of structured lighting. Furthermore, static measurements, in which neither the measuring system nor the measurement object moves at all or only very slowly, require a lot of logistical effort. A large amount of time must be planned for the acquisition of a small measurement volume. [PERSON] [15], [PERSON] and [PERSON] [16], [PERSON] and [PERSON] [17], and others [18; 19] present photogrammetric 3D measurement systems for underwater use. [PERSON] [20] took a different approach, using video streams from a stereo camera. This involved merging successive 3D scans to reconstruct large underwater structures with low accuracy. [PERSON] [21] uses a plenoptic camera for underwater 3D measurements. Underwater 3D measurement systems with structured lighting are currently experiencing increasing development and testing but are not yet used commercially.