Modeling And Calibration Of Underwater Structured Light 3D Measurement System

With the development of politics,military affairs,economy and science and technology in various countries around the world,the demand of people for resources of the types and quantities is increasing.There are abundant resources in the ocean.The development and utilization of human being in marine resources are of great significance to human survival and development.In the process of exploring marine resources,photogrammetric technology is an important means to obtain underwater data.Using underwater 3D measurement technology,the underwater camera takes pictures or videos of underwater objects,and then 3D reconstruction the pictures or videos of underwater objects to obtain underwater information.However,due to the peculiarity and complexity of the marine environment,such as the problem of light refraction,the pictures taken underwater cannot truly represent underwater objects,and underwater 3D measurement technology will also be affected by the underwater environment.Aiming at the problem of light refraction,the land-based 3D measurement technology is no longer suitable for underwater environments.this paper improves the land-based 3D underwater structured light measurement technology,and proposes a 3D underwater structured light measurement technology based on refraction compensation.In the whole process of 3D measurement of underwater objects,the technology of model building and system calibration of underwater 3D measurement is the most important.so it is the focus of this research to solve the problem of model building and system calibration of underwater3 D measurement.In the paper,the influence of refraction of light on underwater 3D measurement system is introduced in detail,the difference between underwater 3D measurement model and land 3D measurement model is analyzed,and the underwater imaging process and underwaterstructural light plane are described in detail.Then a complete underwater 3D measurement model is established according to the conversion relationship between four coordinate systems in the underwater 3D measurement system.After modeling the underwater 3D measurement system,the camera calibration principle based on radial distortion proposed by Tsai and the light plane principle based on constant cross ratio are added to the calibration algorithm.Considering the influence of light refraction,a calibration method of underwater 3D measurement system based on refraction compensation is proposed.Camera imaging point compensation and light plane compensation are applied to the system calibration to complete the calibration of underwater 3D measurement system.Finally,the feasibility of the model and calibration algorithm of the underwater 3D measurement system is verified by measuring the simple underwater object.