How to change Z coordinate or match point clouds

[torsti]

Hi,

First of all I am quite new to CC so please keep it simple for me.

I have two point clouds and the one constructed from UAV aerial photos is a bit noisy and it has some holes. I did some scans to fill the holes on those areas where it was impossible to get aerial photos due to some obstacles. These two point clouds have different Z.

My laser scan data is obviously more accurate than my aerial data so I'd like to move the aerial point cloud to match height of the ground on my laser scan data.

[PCEngineer]

Quick and dirty way would be the following:

First manually find the average Z offset between the reference and aerial point cloud. You could do this by measuring the Delta_Z between the two clouds at different representative points with the 'Point picking' tool.

If you can determine a solid average z offset this way, you can move the entire aerial point cloud with this offset. Do this through 'Edit > Apply Transformation', while selecting the right (aerial) point cloud. Then in the tab 'Axis, Angle' you can insert the Z value for translation.

[daniel]

And to achieve a more robust result, you should use the 'point-pair based registration' tool (http://www.cloudcompare.org/doc/wiki/in ... itle=Align). The challenge will be to find common points / features in both clouds.

And if you have some good overlap between the two types of clouds, you can also try the automatic registration (but anyway you'll need to roughly register the TLS clouds first).