Alignment of two point cloud

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mehmetvozdogan
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Alignment of two point cloud

Post by mehmetvozdogan »

Hi,

I am new with 3D reshaper,

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 to get cross sections for seeing the change..

I can manually align it from transform menu. However precision of alignment depends on user.

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

Thank you...

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gilles_3DR
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Re: Alignment of two point cloud

Post by gilles_3DR »

Hi Mehmet,
How about applying a best fit alignment between the 2 clouds?
The user first needs to align roughly the 2 point clouds and then the software will minimize the distance between the 2 clouds...

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Re: Alignment of two point cloud

Post by mehmetvozdogan »

Hi Giles,

Thank you for your answer,

Is the best fit alignment kind of a registration method? or is it using for only align the two point clouds?

I am trying to align two point cloud of an underground structure. So if it is a kind of registration, it applies transformation and will change the shape of one point cloud to align with the reference. So this will cause an error in change detection analyses

Thank you...

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Re: Alignment of two point cloud

Post by paranoiahasu »

Hi Mehmet

Best fit alignment, rotates your point cloud as a cluster in different axis' instead of transform your coordinate values point by point (this should keep scale factor)

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gilles_3DR
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Re: Alignment of two point cloud

Post by gilles_3DR »

Hi,

The result of the best fit function is a rigid body transformation matrix which is then applied to one of the point cloud. So, no modification in the shape of the point cloud!

You can apply it onto other objects than point clouds: best fit a point cloud onto a mesh, a mesh onto a mesh, a point cloud onto a CAD, a polyline onto a mesh, a polyline onto another polyline...

You can also best fit several point clouds at a time. But there is here a limitation in terms number of point clouds that can be processed!

Another nice feature is that you can block some degrees of freedom, for example, if the scans are levelled, you can force the best fit algorithm to avoid any modifications of the Z axis.

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Re: Alignment of two point cloud

Post by davegrrr »

mehmetvozdogan wrote:
Mon Feb 04, 2019 4:52 pm

I need to align (not register) the both point clouds to get cross sections for seeing the change..
Hi Mehmet,

Are you saying you want to align (but not register) two completely different data sets, or scenes?

Best, David
---
David Gray, Head of Marketing
Vercator software - fast, automatic point cloud registration • vercator.com
Made by Correvate Ltd

mehmetvozdogan
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Re: Alignment of two point cloud

Post by mehmetvozdogan »

davegrrr wrote:
Tue Feb 05, 2019 11:17 am
mehmetvozdogan wrote:
Mon Feb 04, 2019 4:52 pm

I need to align (not register) the both point clouds to get cross sections for seeing the change..
Hi Mehmet,

Are you saying you want to align (but not register) two completely different data sets, or scenes?

Best, David

Hi David,

Yes it is definetly what i want to do. I think Gilles gave me the answer..

Thank you.

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Re: Alignment of two point cloud

Post by mehmetvozdogan »

gilles_3Dreshaper wrote:
Tue Feb 05, 2019 7:51 am
Hi,

The result of the best fit function is a rigid body transformation matrix which is then applied to one of the point cloud. So, no modification in the shape of the point cloud!

You can apply it onto other objects than point clouds: best fit a point cloud onto a mesh, a mesh onto a mesh, a point cloud onto a CAD, a polyline onto a mesh, a polyline onto another polyline...

You can also best fit several point clouds at a time. But there is here a limitation in terms number of point clouds that can be processed!

Another nice feature is that you can block some degrees of freedom, for example, if the scans are levelled, you can force the best fit algorithm to avoid any modifications of the Z axis.


Hi again Gilles,

Thank you for your explanation, i think it will work for me.
But i want to ask one more think, there is a best fit registration button under transfrom menu, is that what you mean with best fit function??

Thank you for your helps
Mehmet.

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Re: Alignment of two point cloud

Post by gilles_3DR »

Yes exactly!
Did you find your way with this command?
Before launching the command, select the 2 point clouds. The 1st selected one will not move.
The 2nd one will move!

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Re: Alignment of two point cloud

Post by mehmetvozdogan »

gilles_3Dreshaper wrote:
Tue Feb 05, 2019 10:27 pm
Yes exactly!
Did you find your way with this command?
Before launching the command, select the 2 point clouds. The 1st selected one will not move.
The 2nd one will move!

Thank you Gilles,

Perfectly done..

Mehmet

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