Study On Tilt Principle And Correct Orientation Method For Three-Dimensional Laser Scanning Point Cloud

People always take some planes or lines as the reference system when they observe and browse the object in the real world,for example,people are accustomed to look and learn it with the upright and horizontal visual angle.However,when people survey and build and analyze model corresponding with object and improve its design with the 3D laser scanning in order to make the visual feeling of 3D model accord with that of the real world,although the orientation target is used in the process of the absolutely orientation,due to the lack of restriction or the worse geometric distribution and only placing fewer targets under the circumstance of scene limit,point cloud data and their coordinate system are usually not the ideal one and then high precision hardly achieve as well.what's more,not only is the efficient of the orient method based on six-parameter method and seven-parameter method and thirteen-parameter method lower but also the process need to place a large number of targets.This paper's point cloud data is picked under the circumstance of placing few orientation target and with the non-ideality geometric distribution,where the point cloud tilt caused by scanner's vertical axis tilt become the key factor of high precision registration and orientation,especially the coordinate error is not tolerated in the application process of high precision scanning.So it is necessary for us to study the propagation law on the point cloud shift,then correct this tilt in order to complete the registration or single dimensional orientation of high precision and fast.Some contents are concluded as follows:? Researching the reason of point cloud tilt and proposing four angle-parameters about tilt,then deducing the error propagation law between each tilt and point cloud coordinate shift,and studying the precision effect of point cloud post-process(point cloud registration or orientation)based on the point cloud tilt.? According to the point cloud tilt description,building the theory model of point cloud tilt and proposing two ways to judge the tilt and a tilt spectrum of RIEGL VZ-1000,at the same time,supplying the basis of theory to checking the 3D laser scanner.? The point cloud tilt have a great effect on the point cloud pre-process precision for the scanning data correction on the basis of placing few artificial target,such as the city scanning with lots of buildings.This paper proposes a algorithm about point cloud correction to solve problems which are brought by point cloud tilt,and then employ the feature of lines and points to orient or register the point cloud quickly with high precision,what's more,propose two kinds of point cloud orientation methods on the basis of vertical line.