Modeling And Reconstruction Of Unstructured Scenes Using 3D Laser Scanning

Effective recognition and perception of environment are two essential tasks for mobile robot's navigation and exploration while working in the unstructured scenes. Especially for 3D scenes modeling and reconstruction, the study has a wide range of applications. The intelligent equipment for 3D scene reconstruction is built in this thesis. Moreover, the geometrical model and 3D grid model are built for 3D scenes. This thesis completes the reconstruction and back review of the 3D scenes.According to the orderliness of laser scanning, the geometrical model is built by extracting the lines, planes, edge contours etc. To complete the data dispatching and visualization in large-scale scenes, a 3D grid model is built by using the octree space partition idea, which divides the laser data into small 3D grids effectively.The classical ICP algorithm completes scene matching iteratively by finding the nearest points to constitute matching pairs. This approach has the disadvantages of slow iterating and converges to a local minimum easily. In this thesis we propose five ways to improve these disadvantages. The scanning pose is needed while matching scenes using ICP. Unfortunately, the scanning pose can not be provided effectively in the most time. Hence, a new method is proposed in this thesis to solve this problem. In the research, a camera is used together with the 3D laser scanner. The mapping relationship of the digital image and the laser range image is obtained by calibrating the parameters between the two kinds of sensors. After the matching pairs in the corresponding digital images are found by the SIFT algorithm, we map them to the laser range image to get the 3D laser matching pairs. At last, the transformation of the two scenes is calculated without scanning pose.Based on the 3D grid model, the data blocking and dispatching of large-scale scenes are solved. According to the distance of grid to the virtual camera in OpenGL space, we divide five areas to dispatch the laser data in 3D grid model. The nearer to the virtual camera, the more data is dispatched and displayed on the screen. A series of experiment results and data analysis show the method's validity and practicability.