ICP using pcregistericp with forcing Scale matrix to identity

Hi,

I want to apply pcregistericp to two point clouds. I know that in theory, ICP works with scaling, rotating and displacement matrices. My question is, how I can force the scale matrix to identity? My objects' size should not change.

PS. I read the pcregistericp m file and it seems it already sets the scale matrix to one. If I am right (?), it is good for my current application. However, why it should be like that when we have scaling in the original icp algorithm?

Thanks.

Answer 1

[Giridharan Kumaravelu]

The pcregistericp function only estimates a rigid transformation (rotation and translation only, no scale). That means the incoming point clouds are expected to correspond to the same scale. There are variants of ICP like SICP that also estimate scale but pcregistericp function implements the algorithm from the following papers as mentioned in its documentation.

[1] Chen, Y. and G. Medioni. “Object Modelling by Registration of Multiple Range Images.” Image Vision Computing. Butterworth-Heinemann . Vol. 10, Issue 3, April 1992, pp. 145-155.

[2] Besl, Paul J., N. D. McKay. “A Method for Registration of 3-D Shapes.” IEEE Transactions on Pattern Analysis and Machine Intelligence. Los Alamitos, CA: IEEE Computer Society. Vol. 14, Issue 2, 1992, pp. 239-256.

[Mostafa Asheghan]

Perfect. Thanls

[Mostafa Asheghan]

And is there a matlab code that does icp with scaling?

[Giridharan Kumaravelu]

No. Currently, MATLAB does not support ICP with scaling. Do you have any usecase where this is required?

[Mostafa Asheghan]

Not really. I am going to have several medical 3d shape registeration afterwards and I was wondering if there is such an option just in case.

Thanks.