3D Reconstruction Of Underwater Objects Based On Line Structured Light Scanning

Underwater target three-dimensional detection is a very important technology inthe research and development of marine, it is brought to the attention of the researchinstitutions and government in every country. The traditional underwater targetdetection technology is given priority to acoustic measurement, but the acousticmeasurement technology has more difficult to meet the real-time and high precisiontask of underwater target three-dimensional and the reconstruction, because of thetechnology’s inherent physical properties. However the underwater photoelectricdetection technology which is based on the optical measurement technology bringstogether the current rapid developed technologies such as: Computer visiontechnology, laser technology, digital image processing technology, electronics andsignal processing technology, etc., at the same time its application scope also becomesmore and more widely. This paper is aimed at improving the existing relativelymature onshore line structured light scanning measurement technology, and making itcan be applied to the special environment of sea water, thus completing the scanningdetection and three-dimensional of underwater target.The research in this paper contents consist of the principle of underwater3-dscanning detection system, camera calibration technique, the image processing oflaser stripes， the extractive technique of stripe center and cente r coordinatetransformation. Camera calibration is the first work to be done before data collecting.This paper uses a direct calibration. With the camera’s direction of motion as acoordinate axis coordinate system of the world, directly to set up a plane pointcoordinate point of mapping relation with the world can avoid calculating thecomplicated camera interior and exterior parameters and system parameters. RandomImage point corresponding to the world coordinate system can required by makinguse of the adjacent point and calibration point to the corresponding world coordinates.The two-dimensional image preprocessing has bigger effect to the whole processing.This article experiment a kind of image enhancement technique based on maximumentropy principle, at the same time, with the help of the median filter technology ofpulse and isolated noise removal. In this paper, the edge extraction is fully introduced.Making use of image morphology processing can refine、cut and skeleton extraction operation the image after edge extraction algorithm. Light stripe center extractionresults the visual effect of3-d reconstruction directly. In this paper, use the gray coreextraction method based on the combination of the skeleton extraction and directiontemplate technology, which can finish the center of laser stripe extraction task verywell. This experiment done in the sink, in to guide control laser and cameramovement scan detect target objects for video data. After middle treatment usingmatlab software programming to achieve the goal of underwater scene3dreconstruction, more clear of objects in3d shape can get through3d reconstruction.Experiments proved the feasibility of the method applied in underwater targetdetection using the scanning and three-dimensional reconstruction.Further, two cameras can be used to target at the same time gatheringinformation and improve the underwater light field lighting for a more precise data fortexture on the surface of the object information at the same time, can accurate3dreconstruction with surface texture information objects.