Research on the Data Processing Method of Vehicle Mobile Measuring Point Cloud in the State of GNSS Lock-out
The position and attitude information of the vehicle-mounted mobile measurement system is mainly provid-ed by GNSS+IMU.When collecting tunnel data,the POS trajectory line after calculation will be distorted and mis-aligned due to loss of GNSS(global navigation satellite system)signal,resulting in serious deformation of laser point cloud position and reduced measurement accuracy.In view of this situation,this paper proposes a point cloud process-ing method that combines dead reckoning and control point correction.Firstly,conventional POS trajectory was solved to obtain the initial POS data,and then dead reckoning was used to smooth the POS trajectory in the GNSS lock-out segment.Finally,target control points were used to correct the position and attitude of smoothed POS,and the scan-ning data are fused to obtain the final point cloud result.The test of a railway tunnel section in operation shows that dead reckoning can eliminate POS trajectory dislocation caused by non-GNSS solution,and the target control point cor-rection can improve the absolute accuracy of tunnel point cloud to millimeter level,which fully meets the requirements of the existing railway measurement accuracy.
vehicle-mounted mobile measurementGNSS lock-outpoint cloud processingcontrol point correction
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