Geometric Correction Of Ground Lidar For Long Range

Lidar is a kind of active measurement method which can quickly obtain the three-dimensional information of the target.It has the advantages of all-weather,high precision and low cost.It has become widely used in the fields of city,transportation and water conservancy.So for its accuracy of the examination also attracted many scholars of the study.The existing distance correction is based on the correction of the waveform parameters,but the waveform parameter correction there is the original waveform data closed,crest detection and waveform correction method is not clear.The existing waveform parameter extraction is based on the Gaussian model to extract the parameters of the echo waveform.This model assumes that there is inconsistency with the non-linear,non-normal distribution and waveform tail lift of the waveform data,resulting in the accuracy of the waveform parameter extraction limit.However,the relative radiation correction method can not directly get the reflection characteristics of objects.The method of ranging correction based on the waveform parameters does not take into account the attenuation factors of the instrument.Not only that,the two-dimensional lidar is calculated by the current changes in the horizontal angle and the vertical angle on the angle of the amount of change,due to the inertia of the instrument in the rotation,the temperature of electronic components,electronic components of the aging lead to horizontal,vertical Right angle acquisition accuracy is not high.So the point cloud data can not really reflect the true information of the objects.Due to the instrument itself,the horizontal angle and the vertical angle of the error,will also affect the echo waveform.There is also a great difference in the atmospheric correction of airborne radar and airborne lidar correction.Airborne lidar atmospheric correction is required to take into account the sun's altitude angle,azimuth,satellite altitude angle,azimuth and data acquisition month and date.The atmospheric correction model of airborne lidar is the correction of vertical direction,in which the particle size and particle density in the atmosphere are very different from the horizontal direction of the ground-based lidar.In this paper,In view of the above-mentioned problems,this paper first resolves the correcting and correcting problem of instrument and equipment.The research contents include: the pointing and ranging error source of the instrument and equipment,the horizontal and vertical angles of the center point of the standard high-reverse standard target,the design of the characteristic column and the characteristic column carrier,and the printing with 3D printing technology The characteristic column and the characteristic carrier are used to paste the reflection sheet on the surface of the characteristic column to make the characteristic point.In the equipment and equipment to lay out the characteristic points,through the feature points to calculate the total station coordinate system to the instrument station coordinate system of the rotation matrix and translation matrix,to achieve the total station coordinate system to the instrument station coordinate system between the conversion,the use of the whole station According to the formula of the laser radar coordinates,the error equation is constructed.Based on the least squares principle,the system error of the instrument and equipment in the horizontal and vertical angles is calculated.Then a new method is proposed to calculate the correction value of the distance measurement.The reflector with 100% reflectivity is designed independently.The coordinate system of the edge of the reflector is measured by the total station.The rotation matrix and the translation matrix are calculated by the feature points.The coordinate equation of the reflector is reconstructed under the coordinates of the total station of the reflector,and the plane equation of the reflector is constructed by using the coordinates of the edge of the converted reflector.As a constraint condition for the lidar distance correction,The coordinate value calculation formula lists the error equation,based on the least squares principle,to calculate the distance correction value.