Detection Of River Geomorphology Based On Structured Light

In recent decades,earthquakes,tsunamis,volcanic eruptions,floods and other natural disasters,causing serious security threats to people at the same time also caused huge economic losses,how to effectively prevent the focus of domestic and foreign scientists,and rivers The river terraces,river alluvial fan,valley form,water system format,river channel change and so on are able to respond to these tectonic activities.One of the most important aspects of the study of river landscapes is underwater detection.In view of the complexity and uncertainty of the underwater environment,it is difficult to obtain relevant information directly from the river.Because of its advantages such as non-contact,high efficiency,high precision,real-time and full-scene measurement.the multi-line structured three-dimensional measurement technology plays an important role in the field of modern measurement,which is an effective method to solve the non-contact 3D measurement problem.In this paper,the three-dimensional measurement of underwater target objects is carried out by using multi-line structured light.The modeling of underwater measurement system based on multi-line structured light and the calibration of the system are mainly studied.In the process of measurement,this experiment adopts the plane type waterproof sea ling cover.Aiming at the technical diffculties in underwater measurement,this paper establishes a new model of underwater line structure light measurement by constructing virtual camera.The intersection of the underwater target point on the structured light stripe to the optical axis of the enclosure is extended to the optical axis of the camera.The intersection with the optical axis is called the virtual optical center.The intersection with the imaging surface is called the virtual imaging point.The distance between the optical center and the imaging plane is called the virtual focal length.The results show that the virtual focal length and the imaginary coordinates of the virtual imaging point are related to the actual focal length of the camera and the distance between the imaging plane of the camera and the refractive plane.Under the action of the virtual camera,the imaging process of the underwater target is linear,and then the 3D reconstruction of the underwater target can be realized by using the constraint relation of the structural light plane.According to the constructed underwater line structure light measurement model,the parameters to be calibrated are the parameters of the camera inside and outside,the structural light plane parameters and the distance between the imaging plane of the camera and the refractive plane.The calibration of the parameters inside and outside the camera is based on the classical calibration method of the camera.On the basis of the invariant principle,the calibration of the structural light plane parameters is carried out by using the coplanar target.The distance between the imaging plane of the camera and the refractive plane is solved by using the three-dimensional coordinate values of the calibration points by bringing the target plane close to the refractive plane.According to the law of light refraction,when the light plane from the air into the water,the light plane will not change any time,so that the calibration of the parameters can be completed in the air.The experimental results indicate that using the above methods of calibration error is less than 0.5 pixel camera parameters,calibration of the light plane structure parameter error of the mean is 0.7675 pixel,measured using this model,a distance of 2.45 m,the average error is 1.6443 mm,with high measurement precision,can meet the demand of the actual measurement.