# Bspline FFD registration

**URL:** <https://discourse.itk.org/t/bspline-ffd-registration/4682>\
**Category:** Uncategorized\
**Created:** [December 17, 2021, 5:29pm UTC](https://discourse.itk.org/t/bspline-ffd-registration/4682 "2021-12-17T17:29:38Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![VeerBal](https://discourse.itk.org/letter_avatar_proxy/v4/letter/v/71c47a/32.png) [@VeerBal](https://discourse.itk.org/u/VeerBal)\
**Post date:** [December 17, 2021, 5:29pm UTC](https://discourse.itk.org/t/bspline-ffd-registration/4682/1 "2021-12-17T17:29:38Z")

</div>

Hi there

So I’m registering 2 lung CT images of same subject at different time points using the Bspline FFD approach . These lung images are in .mha format and I’m using the same approach as done in the POPI model.

So after iterating my output looks like this where I’m getting a rounding error .  
14408.027  
Optimizer’s stopping condition, A rounding error occurred or line-search steps have an insufficient reduction  
Iteration: 50  
Metric value: 14402.493636195337

My optimizer conditions are as follows  
registration\_method.SetOptimizerAsLBFGS2(solutionAccuracy=1e-4, numberOfIterations=100, deltaConvergenceTolerance=0.01)

Can you provide some insights of what might be causing this .

Thank you