The Study Of Preprocessing On The Point Cloud From The Unmanned Automatic Stacker-reclaimer System For Port Coal

Port yard automatic unmanned material piling and taking system has important meaning for the development of our national economy, and one of the core contents of the system is to obtain and analyse the material information. In this article, taking the laser scanner as collecting tools, based on the analysis of the structure of point cloud data which is collected, for practical applications, a relatively complete set of data processing algorithm is formed, which is from the data acquisition and conversion to simplifying and inversion of data, and then to the storage and update. The main research contents of this artical include the following aspects:Firstly, according to the practical work in coal field, combined with various parameters of coal yard cart and scanner, the formula for the transform form the length data which is collected from the laser scanner to data of 3D point cloud. Then the possible deviation angle and deviation distance in practical application are discussed, and the relevant correction formula is given.Secondly, according to real-time requirement, the simplification and triangulation algorithm for point cloud data is studied. Considering the point cloud is formed in line structure, a 2-step simplification method for point cloud which based on line structured light scanning is put forward. First, the point cloud in each row is simplified by the minimum distance- deviation angle streamline method; then using the improved Delaunay triangulation based on line structured light scanning, the point cloud data is triangulated; finally, with Voronoi neighborhood which obtained by the former triangulation, using the method based on the least square plane, the redundancy point cloud data between lines are simplified.Thirdly, according to the actual requirement of the storage and update of point cloud data in coal yard, a point cloud storage algorithm is designed. In this algorithm, firstly, the three-dimensional point cloud data is transformed to be one-dimensional with Morton code; and then using the block algorithm, the uniform meshes for point cloud are merged into larger blocks, and thaking the block as a whole, the point data are put into the database. When update, first, we find the uniform grid’s edges which may override the useful data and remove them, and then we divide the area into block and update them into the database.Finally, the experiment system for the processing of point cloud data in coal yard is introduced, whith is used to verify the effectiveness of the algorithm and determinate parameters in the algorithm. In the experimental system, it is very convenient to find appropriate parameters and to test whether the algorithm can meet the predetermined target. The experiment proved the rapidity and effectiveness of the method.