Research On Key Techniques Of Structured Light 3-D Measurement

The measurement of shape and scale is one of basic methods which are used to rebuild the world by mankind. In recent years, structured light 3-D measurement has attracted a great deal of attention in industrial environment because of its following characters: high precision, easy to abstract the information from laser stripe image and strong real-time ability, etc. This technique is too important to be replaced by others in the fields of 3-D auto-measurement and object recognition.This dissertation has carried out research deeply on the key problems of the project through the development practice of Ship Subsection Measurement System. The key problems include system modeling, parameter calibration, laser stripe abstract and edge detection of range image.Many different system models emerged on the base of the basic principle of laser stripe structured light. Not only is the system model on the principle of triangulation built, but also a Direct Mapping Model is put forward in this thesis. It is necessary to calibrate the system after the system model is built. The calibration of structured light 3-D measurement system includes two steps: camera calibration and system structural parameter calibration. On the base of summing up the existed calibration methods, the Interpolation Calibration Method Based on the Direct Mapping Model is presented. "With the help of the calibration method, we need not calibrate the intrinsic and extrinsic parameters and structural ones. It reduces the complexity of the system and is credible and insensitive to interim parameters.Laser stripe abstract is used to capture objects' information by laser stripe structured light system. Many methods of laser stripe abstract are discussed in the paper. And then the Adapted Window Curve Fitting Method is presented and used to calculate the center coordinates of laser stripe. This method has great adapted character for the width of laser stripe. In order to strengthen the integrality of laser stripe, the Parabola Fitting Curvature Extension Method is used to repairing unconnected lines.To reduce the quantity of data and obtain distinct characters about objects, we conduct edge detection for range image. A robust edge detection algorithm is realized and experiments prove its applicability.