Align two clouds and preserve correct elevations

[mlc183]

Hello,
I have two point clouds that are two sections of the same gravel bar. I need to align them and merge them into 1 cloud. I have tried doing this using the translate/rotate tool, but this changes the elevations of known points within my cloud (I have permanent GCPs at my site that have been surveyed so I know the true point elevations). The two clouds also share overlap, so I know that they can be tied together. Is there a better way to merge them that won't change my known elevations?
Thank you for your time!

[daniel]

Normally, if one of your cloud is already correctly positioned, then it should be used as 'reference', and you should only move the other cloud. Either manually indeed, or with the Point-pair alignment tool, or the Fine registration (ICP) tool. See http://www.cloudcompare.org/doc/wiki/in ... gistration.

As long as you never move the reference cloud (and the alignment tools will do the same), then your coordinate system should be preserved.