GNSS失锁时车载激光扫描点云精度提高方法研究

Research on Improving Precision of Point Cloud when GNSS Out of Lock Based on Vehicle Laser Scanning

为解决车载激光扫描系统因GNSS偶然失锁造成采集点云精度低等问题,采用布设不同控制点网形的方法对车载点云数据精度进行提高。实验流程为将车载激光扫描系统置于GNSS失锁状态下进行点云数据采集,通过3种不同控制点布设网形得到校正控制点,并对点云数据进行校正,研究不同控制点布设网形对点云精度提高的影响。研究表明,每100 m布设1个控制点,直线网形控制点校正后的点云平面精度为0.0296 m,高程精度为0.0328 m;双直线网形点云平面精度为0.0577 m,高程精度为0.0282 m;折线网形点云平面精度为0.0799 m,高程精度为0.0553 m。每300 m布设1个控制点,直线网形控制点校正后的点云平面精度为0.1437 m,高程精度为0.0375 m;双直线网形点云平面精度为0.1318 m,高程精度为0.0496 m,折线网形点云平面精度为0.1218 m,高程精度为0.0501 m。每500 m布设1个控制点,直线网形控制点校正后的点云平面精度为0.2111 m,高程精度为0.0458 m,双直线网形点云平面精度为0.2136 m,高程精度为0.0516 m;折线网形点云平面精度为0.2110 m,高程精度为0.0632 m。研究结果表明,控制点密度越高,点云精度提高的效果越好;在同等密度下,直线形网形较其他两种网形更为简单,且点云精度提高效果更好。

In order to solve the problem of low accuracy of point cloud collection caused by GNSS accidental loss of lock during the operation of vehicle mounted laser scanning system,the method of laying different control point nets was adopted to improve the accuracy of vehicle mounted point cloud data.The experimental process was to put the vehicle laser scanning system in the GNSS lock out state for point cloud data acquisition.The point cloud data was corrected by the correction control points obtained by three different control points layout network shapes,and the influence of different control points layout network shapes on the improvement of point cloud accuracy was studied.The result shows that:the higher the density of control points in the network,the better the effect of improving the accuracy of point cloud.When one control point is set every 100 meters,the plane precision of point cloud is 0.0296 m and the elevation precision is 0.0328m after the correction of linear network control points.The plane precision of point cloud after the correction of double linear network control points is 0.0577 m and the elevation precision is 0.0282 m.The plane precision of point cloud after the correction of broken line network control points is 0.0799 m and the elevation precision is 0.0553 m;when one control point is set every 300 meters,the plane precision of point cloud is 0.1437 m and the elevation precision is 0.0375 m after the correction of linear network control points.The plane precision of point cloud is 0.1318 m and the elevation precision is 0.0496 m after the correction of double linear network control points.The plane precision of point cloud is 0.1218 m and the elevation precision is 0.0501 m after the correction of broken line network control points;when one control point is set every 500 meters,the plane precision of point cloud is 0.2111 m and the elevation precision is 0.0458 m after the correction of linear network control points.The plane precision of point cloud after the correction of double linear network control points is 0.2136 m and the elevation precision is 0.0516 m.The plane precision of point cloud after the correction of broken line network control points is 0.2110 m and the elevation precision is 0.0632 m.In the case of the same density of control points,the layout of linear control points is simpler than the other two kinds of network,and the effect of improving the accuracy of point cloud is better.