How to return the RMSE using the pcregistericp function?

I have been using the pcregistericp function with MATLAB R2021a to align two 3d scans. So far, through visual inspection, the function has aligned the scans correctly. However, I would like a quantitative measure of the alignment of the two scans. I tried to get the function to return the RMSE using the command found in the MATLAB documentation, [t,rmse] = pcregistericp(moving,fixed). This, however, did not work as the RMSE variable was returned as a point cloud rather than a positive scalar representing the RMSE between the data sets.

At first, I thought the RMSE wasn't being returned because the data sets were not the same size (hence the use of the open form of ICP). To test this theory, I made the two point clouds from the same data set (thus, ensuring that the number of points are the same). After doing this, the RMSE was still not returned.

I would appreciate any insight into this issue.

Answer 1

[Carter Taylor]

I found this answer on Stack Overflow:

"The problem is already solved. The previous outcome variable "rmse" is actually a point cloud. I tried to modify the variable rmse to the third output argument.

[tform,temp,rmse] =pcregrigid(ptCloud,ptCloud2,'Metric','PointToPoint','Extrapolate',true)"

This seemed to work; however, if anyone has any other solutions, I would be happy to see them.

It should also be noted that making a third argument in [t,rmse,RMSE_Real] = pcregistericp(moving,fixed); returns the rmse of the data and fixes my issue.

I'm just writing this solution here in case anyone is having the same issue!