Opti-Acoustic Stereo Imaging, System Calibration and 3-D Reconstruction

Utilization of an acoustic camera for range measurements is a key advantage for 3-D shape recovery of underwater targets by opti-acoustic stereo imaging, where the associated epipolar geometry of optical and acoustic image correspondences can be described in terms of conic sections. In this paper, we propose methods for system calibration and 3-D scene reconstruction by maximum likelihood estimation from noisy image measurements. The recursive 3-D reconstruction method utilized as initial condition a closed-form solution that integrates the advantages of so-called range and azimuth solutions. Synthetic data tests are given to provide insight into the merits of the new target imaging and 3-D reconstruction paradigm, while experiments with real data confirm the findings based on computer simulations, and demonstrate the merits of this novel 3-D reconstruction paradigm

Integration of Motion Cues in Optical and Sonar Videos for 3-D Positioning

Target-based positioning and 3-D target reconstruction are critical capabilities in deploying submersible platforms for a range of underwater applications, e.g., search and inspection missions. While optical cameras provide high-resolution and target details, they are constrained by limited visibility range. In highly turbid waters, target at up to distances of 10 s of meters can be recorded by high-frequency (MHz) 2-D sonar imaging systems that have become introduced to the commercial market in years. Because of lower resolution and SNR level and inferior target details compared to optical camera in favorable visibility conditions, the integration of both sensing modalities can enable operation in a wider range of conditions with generally better performance compared to deploying either system alone. In this paper, estimate of the 3-D motion of the integrated system and the 3-D reconstruction of scene features are addressed. We do not require establishing matches between optical and sonar features, referred to as opti-acoustic correspondences, but rather matches in either the sonar or optical motion sequences. In addition to improving the motion estimation accuracy, advantages of the system comprise overcoming certain inherent ambiguities of monocular vision, e.g., the scale-factor ambiguity, and dual interpretation of planar scenes. We discuss how the proposed solution provides an effective strategy to address the rather complex opti-acoustic stereo matching problem. Experiment with real data demonstrate our technical contribution

Optiacoustic stereo imaging: On system calibration and 3-D target reconstruction,” in review

Utilization of an acoustic camera for range measurements is a key advantage for 3-D shape recovery of underwater targets by opti-acoustic stereo imaging, where the associated epipolar geometry of optical and acoustic image correspondences can be described in terms of conic sections. In this paper, we propose methods for system calibration and 3-D scene reconstruction by maximum likelihood estimation from noisy image measurements. The recursive 3-D reconstruction method utilized as initial condition a closed-form solution that integrates the advantages of so-called range and azimuth solutions. Synthetic data tests are given to provide insight into the merits of the new target imaging and 3-D reconstruction paradigm, while experiments with real data confirm the findings based on computer simulations, and demonstrate the merits of this novel 3-D reconstruction paradigm. 1

View-invariant Pose Analysis for Human Movement Assessment from RGB Data

International audienceWe propose a CNN regression method to generate high-level, view-invariant features from RGB images which are suitable for human pose estimation and movement quality analysis. The inputs to our network are body joint heatmaps and limb-maps to help our network exploit geometric relationships between different body parts to estimate the features more accurately. A new multiview and multimodal human movement dataset is also introduced to evaluate the results of the proposed method. We present comparative experimental results on pose estimation using a manifold-based pose representation built from motion-captured data. We show that the new RGB derived features provide pose estimates of similar or better accuracy than those produced from depth data, even from single views only