Underwater 3D shape measurement using inverse triangulation through two flat refractive surfaces

This work describes a physical refraction model stereo vision system calibration. A back projection and a stereo optimization are used to find the cameras axis and distances from its central point to the water tank glass. The system performs inverse triangulation, also known as mesh oriented measurements. In order to evaluate the refraction model performance, laboratory experiments were conducted and the measurement error of two calibrated spheres were compared to air acquisitions. A mannequin face is also used as a complex shape underwater measurement sample.