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Different results for every cloud compare aligning module

Posted: Mon Jun 22, 2020 1:53 am
by soheilsabz
I have tried cloudcompare and the aligning c2m module like this:

Image
and give transformation matrix lie this:
Image
[![enter image description here][4]][4]

For one **STL** file twice and get different result for under 0.1 value in max distance like show at below pictures:

first one :
Image
Second aligning try:

Image
so i like to know why this difference in results happen? does every time which i use align module it create different transformation matrix ?
ALSO ASKED HERE:

https://engineering.stackexchange.com/q ... ing-module


Update:

My guess is that happens because of **difference** between The reference STL points and the aligned target points, which here for reference is almost 26,000 point and target almost 200,000 point. which needs to select random point based of reference points in target STL file for aligning.
Thanks.

Re: Different results for every cloud compare aligning module

Posted: Tue Jun 23, 2020 9:11 pm
by daniel
By default CC uses a random process (at each iteration, different vertices/points are used). This allows to use much less points and therefore go much faster (with 'similar' results).

To avoid this, you can set the 'research' parameter named 'Random sampling limit' and set it higher than the number of points or vertices in your aligned cloud.