CloudCompare forum

Hello,

My scanner accuracy is ±0.13 mm. Does this affect the results of M3C2 distances? for examples, if the mean from M3C2 is 0.0002 mm and std is 0.0331 mm or -0.0003 mm and std is 0.0383 mm or 0.003 mm and std is 0.042 mm. Note all the averages of distances uncertainties are approx. 0.01 mm.

How to know if the uncertainties are due to the registration errors or roughness?


Thanks

M3C2 tries to average the local displacement and therefore reduce the effect of noise. However it depends on a lot of parameters (scale / density, actual type of displacement and if it's applied to large objects / surfaces, etc.

And yes the registration error should definitely be taken into account when dealing with such low distances... But getting the right value is hard. It's mostly used for flagging the changes as meaningful or not actually (the confidence scalar field).

Thanks for your reply. I have fixed the normal in the vertical direction. Does this mean vertical displacement and also can be called different in surface heights between two point clouds?
So this has nothing to do with the scanner accuracy? and if distance uncertainties are 0.01 mm

Thanks

Also, does vertical displacement has anything to do with erosion or deposition? I just don't know what to do with the value I get from the M3C2 (mean and standard deviation) I don't know what they mean in terms of the change rate

thanks