How to set contraint on transformation matrix?

[amir-opal]

Checklist

• I have searched for similar issues.
• For Python issues, I have tested with the latest development wheel.
• I have checked the release documentation and the latest documentation (for master branch).

My Question

I am working on a problem where all point clouds have their vertical axis aligned, e.g., the z-axis of all point clouds are the same. I want to apply point cloud registration on them. I know that the rotation matrix of the transformation should be a rotation around the z-axis. Thus, I want to set a constraint on the transformation matrix so that the resulting rotation matrix of registration is exactly a rotation around the z-axis. I do not want the algorithm to search for the rotation matrix among all available matrices. I wonder whether there is any implementation so that I cant put this constraint when I want to register the point clouds.

[ssheorey]

Hi @amir-opal this is not supported yet. What is your use case? In most cases, the point clouds may be "almost" aligned along the Z axis, but not perfectly. e.g. automotive or mobile robot lidar point clouds. The Z axis will change if the car drives up a slope, etc.

[amir-opal]

Hi @ssheorey. I want to use it for the case that I have the scans of rooms of an indoor space, and I want to stitch them. In this case, all of the point cloud have exactly their z-axis aligned. Is there any way to apply this constraint? or I should write this function from scratch?

[ssheorey]

Please submit a PR if you implement this from scratch!
Related: #409