[Insight-developers] Uniform registration results

[Blezek, Daniel J (GE, Research)]

Hi,  I made the change and the test passed, so I'll check it in.  Please watch the dashboards with me the next day or so.
 
Regards,
-dan

-----Original Message-----
From: Stefan Klein [mailto:stefan at isi.uu.nl]
Sent: Tuesday, April 04, 2006 11:04 AM
To: Blezek, Daniel J (GE, Research); insight-developers at itk.org
Subject: Re: [Insight-developers] Uniform registration results


Hi,

Quite a while ago this email was sent (see below). I just noticed it while scrolling through some older mails.

The SPSAOptimizer still seems to use the old random generator. Could it also be changed to use the MersenneTwister? 

Regards!
Stefan.



At 08:40 28/09/05, Blezek, Daniel J (Research) wrote:


One problem that has plagued me for some time is the different registration results from different platforms.  The problem is in the Random image iterator used to draw samples from the images being registered.  On Unix-like systems, drand48 is used, under Windows (as best I can make out) there is a C++ implementation.  They give a different sequence of random numbers, as you might expect.  This leads to different minimum in the registration process.

To fix this, I've changed the random iterators to use the MersenTwister RNG.  Some tests fail because they are not exactly the same (registration is off by < 0.1 pixels/mm).  The tests that fail are:

The following tests FAILED:
        965 - ImageRegistration4oTest (Failed)
        972 - ImageRegistration4Test (Failed)
        979 - ImageRegistration13Test (Failed)
        982 - ImageRegistration16Test (Failed)
        984 - MultiResImageRegistration1Test (Failed)
        985 - MultiResImageRegistration2Test (Failed)

I've verified the final parameters are very close to the previous results.  Is there an owner of these tests?  If so, can I send a patch and have you verify the results?  Otherwise I'll plan to check the code in with new baseline images.

Regards,
-dan


Daniel Blezek, PhD
GE Global Research
Computer Scientist

T 518 387 5481
F 518 387 6981
D *833-5481
E blezek at research.ge.com
www.research.ge.com <http://www.research.ge.com/> 

1 Research Circle
Niskayuna, NY 12309, USA

General Electric Company

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