Refraction-Based Dome Port Camera Calibration

In underwater environments, the dome port can withstand higher water pressure to better protect the camera. In addition, it provides a wider field of view for the camera. However, if the center of the camera and the center of the dome do not coincide, the light received by the camera will be refracted, which can cause serious distortion in the captured image. To deal with this problem, this paper proposes a more effective calibration method for underwater cameras using dome ports. We firstly deduce the transformation matrix between the camera coordinate system and the dome coordinate system, which ensures that all linear calculations of calibration parameters can be performed in the same coordinate system. Then to make the iterations sufficient to obtain optimization results closer to the true value, we introduce a two-layer nested nonlinear optimization based on the back projection of 3D points. Finally, we measure the calibration results.