Alignment of two point cloud

Discuss all CloudCompare issues here.
Post Reply
mehmetvozdogan
I have made 10-20 posts
I have made 10-20 posts
Posts: 18
Joined: Fri Feb 01, 2019 9:49 pm
Full Name: Mehmet Volkan Ozdogan
Company Details: Dokuz Eylul University
Company Position Title: Research Assistant
Country: Turkey
Linkedin Profile: Yes

Alignment of two point cloud

Post by mehmetvozdogan » Tue Feb 19, 2019 7:37 pm

Hi,

I have two registered point cloud data of same place. They are taken in various dates.
But both of the point cloud have own coordinate system.
I need to align (not register) the both point clouds for m3c2 analysis.
I can manually align it but precision of alignment depends on user.

Is there any other methods for alignment of two point cloud data for more precision leveling.

Thank you...

User avatar
danielgm
V.I.P Member
V.I.P Member
Posts: 153
Joined: Thu Jun 20, 2013 10:45 am
Full Name: Daniel Girardeau-Montaut
Company Details: CloudCompare
Company Position Title: Administrator
Country: France
Linkedin Profile: Yes
Location: Grenoble, France
Contact:

Re: Alignment of two point cloud

Post by danielgm » Tue Feb 19, 2019 8:46 pm

Once both clouds are roughly aligned you can use the 'ICP' tool (https://en.wikipedia.org/wiki/Iterative_closest_point). This should reduce user-dependent errors (but it's still necessary that both clouds are already roughly aligned before using this tool).

Mind the 'overlap' parameter that is the only one that you should really care about ;)
Daniel
CloudCompare admin
http://www.cloudcompare.org/

mehmetvozdogan
I have made 10-20 posts
I have made 10-20 posts
Posts: 18
Joined: Fri Feb 01, 2019 9:49 pm
Full Name: Mehmet Volkan Ozdogan
Company Details: Dokuz Eylul University
Company Position Title: Research Assistant
Country: Turkey
Linkedin Profile: Yes

Re: Alignment of two point cloud

Post by mehmetvozdogan » Tue Feb 19, 2019 9:08 pm

danielgm wrote:
Tue Feb 19, 2019 8:46 pm
Once both clouds are roughly aligned you can use the 'ICP' tool (https://en.wikipedia.org/wiki/Iterative_closest_point). This should reduce user-dependent errors (but it's still necessary that both clouds are already roughly aligned before using this tool).

Mind the 'overlap' parameter that is the only one that you should really care about ;)
Hi Danie,

Thank you for your answer but i think if i use ICP tool, shape of one point cloud will change according to references poin cloud shape.

i have two various dated point cloud data of underground drift and i want to determine the deformation of drift. So shape of the point clouds must be prevented. The alignment must be done with only rotation of point cloud

User avatar
danielgm
V.I.P Member
V.I.P Member
Posts: 153
Joined: Thu Jun 20, 2013 10:45 am
Full Name: Daniel Girardeau-Montaut
Company Details: CloudCompare
Company Position Title: Administrator
Country: France
Linkedin Profile: Yes
Location: Grenoble, France
Contact:

Re: Alignment of two point cloud

Post by danielgm » Tue Feb 19, 2019 9:41 pm

ICP doesn't change the shape (if you don't check the "Adjust scale" option). It will only move the aligned cloud.

Both the ICP and the 'Point pair based' alignment tools produce (and apply) a rigid transformation matrix on output.
Daniel
CloudCompare admin
http://www.cloudcompare.org/

mehmetvozdogan
I have made 10-20 posts
I have made 10-20 posts
Posts: 18
Joined: Fri Feb 01, 2019 9:49 pm
Full Name: Mehmet Volkan Ozdogan
Company Details: Dokuz Eylul University
Company Position Title: Research Assistant
Country: Turkey
Linkedin Profile: Yes

Re: Alignment of two point cloud

Post by mehmetvozdogan » Tue Feb 19, 2019 9:52 pm

danielgm wrote:
Tue Feb 19, 2019 9:41 pm
ICP doesn't change the shape (if you don't check the "Adjust scale" option). It will only move the aligned cloud.

Both the ICP and the 'Point pair based' alignment tools produce (and apply) a rigid transformation matrix on output.
Thank you for the help and information Daniel..

User avatar
Daniel Wujanz
I have made 20-30 posts
I have made 20-30 posts
Posts: 20
Joined: Fri Aug 24, 2018 11:26 am
Full Name: Daniel Wujanz
Company Details: technet GmbH
Company Position Title: 3D Laser Scanning Specialist
Country: Germany
Linkedin Profile: Yes
Location: Berlin
Contact:

Re: Alignment of two point cloud

Post by Daniel Wujanz » Wed Feb 20, 2019 8:41 am

Dear Mehmet,

it is vital that you remove the areas that are subject to deformation BEFORE you apply the ICP! Otherwise the transformation parameters will be biased and your deformation map will be rubbish. If you're interested why this happens please have a look at the following article (if you don't have access I can also send you a pdf): Wujanz, D., Krueger, D., & Neitzel, F. (2016). Identification of stable areas in unreferenced laser scans for deformation measurement. The Photogrammetric Record, 31(155), 261-280.

All the best

Daniel

Post Reply

Return to “CloudCompare”