[Insight-developers] itkSimpleImageRegistrationTest failing (gcc 4.4 change in floating point computation)

[Bill Lorensen]

Brad,

It looks like there are already 3 baselines. And, according to the
test output, the second baseline is pretty close to the results of the
2 failing platforms. Seems that the displayed error images are from
the first baseline.

Perhaps we just need a higher tolerance. Something greater than 31.

Also, we may have a bug in the regression testing that causes the
wrong difference image to be used.

Bill

On Mon, Feb 27, 2012 at 10:51 PM, Bradley Lowekamp
<blowekamp at mail.nih.gov> wrote:
> Hello,
>
> The itkSimpleImageRegistrationTest  is failing on a couple systems. Perhaps those with newer versions of gcc (gcc4.4+ )
>
> http://open.cdash.org/testSummary.php?project=2&name=itkSimpleImageRegistrationTest&date=2012-02-26
>
> They appear to be consistently failing in the same way each night and across the platforms. Why do I think it's failing? I hope someone has more insight, but it appears that gcc has changed something in how it does/optimized floating point computation so that results are slightly different. My first potentially relavent google hit:
>
> http://stackoverflow.com/questions/8802831/gcc-rounding-difference-between-versions
>
>
> It is not clear to me if the output is "close" enough to be considered correct. Specifically, the bottom right appears to be more then a pixel off in the registration. Is it correct enough?
>
> If it is I am tempted to add a second baseline image to the test ( as opposed to adding tolerances  to the comparison ).
>
> Thought on how to clean up the dashboard further?
>
> Brad
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