[Insight-users] Fixing the Image Orientation issue for ITK 3.10

[Gaëtan Lehmann]

Le 16 oct. 08 à 19:47, Karthik Krishnan a écrit :

> On Thu, Oct 16, 2008 at 1:23 PM, Luis Ibanez  
> <luis.ibanez at kitware.com> wrote:
>>
>> Hi Karthik,
>>
>> Thanks for the clarification.
>>
>> It seems that we should move the Transform Index <--> Point
>> methods to the ImageBase class and have them to be shared
>> by the Image, OrientedImage and VectorImage.
>
> Or we could copy the methods over from OrientedImage into the
> VectorImage class, so as to make VectorImage also "oriented".
>
> They are pretty small methods. The whole OrientedImage class in
> itself is less than 100 lines. I think virtualizing those methods  
> might
> introduce a performance hit. I agree that profiling is a great idea.
>

It would be great to have them in the base class, so all the  
subclasses can have them. I have copied them in 2 new classes (not yet  
in the Review directory) - itk::LabelMap and itk::ComponentTree - both  
are subclasses of itk::ImageBase.
However, IIRC, those templated methods can cause some problems to some  
compilers if they are implemented in a base class.

Gaëtan

> Thanks a lot
> --
> karthik
>
>
>>
>> I'm profiling the overhead of the virtual call with respect
>> to the multiplications and additions that are currently
>> computed in these methods.
>>
>> Once we have timing numbers we can review how important is
>> for these methods to avoid being virtual, and whether a
>> different implementation can provide the desired behavior.
>>
>>
>>  Luis
>>
>>
>> -----------------------
>> Karthik Krishnan wrote:
>>>
>>> Luis Ibanez wrote:
>>>
>>>>
>>>> Hi Karthk, Gordon,
>>>>
>>>>
>>>> This problem has been solved since September 13th 2008.
>>>>
>>>>
>>>> Simply turn on the CMake flag:
>>>>
>>>>
>>>>         ITK_IMAGE_BEHAVES_AS_ORIENTED_IMAGE
>>>>
>>>>
>>>> That will make the itk::Image behave like the itk::OrientedImage.
>>>>
>>>>
>>>> Since the itk::VectorImage derives from the itk::Image,
>>>
>>> It derives from itk::ImageBase. If I recall correctly, at that time,
>>> deriving
>>> from itk::Image required me to make certain methods like
>>> TransfromPhyscalPointToContinuousIndex virtual. Same reason why
>>> OrientedImage derives from ImageBase and not Image.
>>>
>>> Thanks
>>> --
>>> karthik
>>>
>>>> then
>>>> the correct behavior will also be inherited.
>>>>
>>>>
>>>>  Thanks
>>>>
>>>>
>>>>     Luis
>>>>
>>>>
>>>>
>>>> -------------------------
>>>> Karthik Krishnan wrote:
>>>>
>>>>> Dan, Gordon:
>>>>>
>>>>> As you've already realized Dan, itk::VectorImage provides no  
>>>>> more (and
>>>>> no less)
>>>>> support for direction cosines than itk::Image. They simply  
>>>>> ignore it and
>>>>> do not,
>>>>> unlike itk::OrientedImage, take it into account when translating  
>>>>> indices
>>>>> into
>>>>> world coordinates, or use it when computing derivatives on images.
>>>>>
>>>>> NRRD, I believe, allows for encoding both the patient coordinate  
>>>>> system
>>>>> (represented by space_origin and space_directions) and additional
>>>>> coordinate systems pertinent to DWI images (gradient coil's  
>>>>> directions).
>>>>> Whatever direction cosines it will set on itk::Image or  
>>>>> itk::VectorImage
>>>>> are
>>>>> ignored.
>>>>>
>>>>> In retrospect, I mistakenly derived VectorImage from ImageBase,  
>>>>> rather
>>>>> than OrientedImage, but both classes came out the same year, when
>>>>> OrientedImage was still in its infancy with a CVS log stating
>>>>> "It may be removed be before the next release".
>>>>>
>>>>> As a solution, the VectorImage class could quite easily be made to
>>>>> take into account of the direction cosines exactly as  
>>>>> OrientedImage
>>>>> does,
>>>>> by just copying the methods over from OrientedImage. Perhaps that
>>>>> could be on the list of things ToDo whenever the next lengthy
>>>>> discussion on Orientation comes up in ITK. I think we have one
>>>>> every month. :)
>>>>>
>>>>> Thanks
>>>>>
>>>
>>
>
>
>
> -- 
> Karthik Krishnan
> R&D Engineer,
> Kitware Inc.
> Ph: 518 371 3971 x119
> Fax: 518 371 3971
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk.org
> http://www.itk.org/mailman/listinfo/insight-users

-- 
Gaëtan Lehmann
Biologie du Développement et de la Reproduction
INRA de Jouy-en-Josas (France)
tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
http://voxel.jouy.inra.fr  http://www.mandriva.org
http://www.itk.org  http://www.clavier-dvorak.org

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