LIDAR POINT CLOUD ALIGNMENT

the registration of the point clouds should be tied to the collection platform, i.e. fixed wing/gps/imu with a base station GPS and appropriate GCPs.

If you flew a drone, similar protocols etc to tie down the elevations of the clouds, but more importantly how they're registered between each other. If the control is set up on each reach (based on what you're depicting in the image) the BMs used for each one would become the baseline for the elevation and registration of the project.

more information is needed on what differences you're seeing and what the workflow was when the collection occured.

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Would aligning the point clouds via GCP's in Cloudcompare work??ÿ Stated more as a question as my knowledge of the program is largely from reading and watching videos about it.?ÿ It is open source so it may be a cheap method to try first.

ie. Not exactly what you are looking for, but a very simple example of what I was talking about:

I can't tell how much vertical discrepancy there is between the two clouds, but if it's obviously out of tolerance I would first suspect processing methodology and/or control point values. Even different runs should be matching up in the overlap areas.

Some of our larger projects incorporate both mobile and aerial LiDAR, and the mobile mapping runs usually match up with our sUAS point clouds within 1-2cm, using different processing software, different raw data and often slightly different methodology.

Sometimes the data are gathered weeks or months apart. It's all about the control and the processing workflow.

As for fixes, cloud to cloud is going to be tricky with that small amount of overlap, especially if there aren't many identifiable features in the common areas. I wouldn't have much confidence in a river bed to extract common points in automated routines.