I think most of us assume that the IMU – inertial measuring unit in a mobile LiDAR system only comes into play when GPS is not available, such as when you are in a tunnel or in an urban canyon. Turns out that is not the case. With the GPS updating 5 or maybe 10 times per second and the scanners spinning at 500,000 times per second in some cases the system is using the IMU all the time which introduces a lot more uncertainty into the solution.
Each IMU – derived position is sequential – it depends on the previous position which means any error in the starting position is going to be magnified as time progresses. This is what makes the kinematic use of LiDAR so much more challenging and why when you here people say that the accuracy of the point cloud is approaching the accuracy of the control that you want to be cautious.
To remove the uncertainty of the trajectory from the error budget will require very dense control which could defeat the purpose of using mobile in the first place. It is important to remember every point in the cloud has its own unique georeferencing solution so if you are interested in 95% confidence in your results you have a lot of work to do.
