multi-Grid Bspline Image Registration error

Hi, I am testing the examples provided officially, DeformableRegistration6.cxx.
The first 2 stages went well. But the third stage stopped at step 15 and exited with an error information “Optimizer stop condition = A rounding error occurred”.
I did not change the original code and the testing platform is Win10+VS2019.
What happened here and how to solve this problem?

I don’t think I heard that before. What inputs are you giving to DeformableRegistration6.cxx? The ones in the test or your own data?

I am using RatLungSlice1 and RatLungSlice2 in the test.

If you provide links to those images, someone could try to reproduce the problem.

The files are included here. By the way, I am using ITK 5.0.1
RatLungSlice1.mha (177 Bytes) RatLungSlice1.raw (16 KB) RatLungSlice2.mha (177 Bytes) RatLungSlice2.raw (16 KB)

Judging by this comment, this seems like a normal stop condition. The error message does make it sound confusing. The output file is produced. While the registration could benefit from limiting the amount of deformation, it does look reasonable.

I just made a PR which hopefully clarifies the message: