[Insight-users] How to concatenate itk transformations

[Stefan Klein]

Hi Jian,

No, saving has not (yet) been implemented in Serial/Combination 
transform. As Sebastien suggested, you may use the BSplineTransform if 
you have only two transforms. However, it seems to me that the 
m_BulkTransform is also not saved to disk (but I may be wrong here, 
since I have no experience with the ITK mechanism for saving transforms).

Kind regards,
Stefan.

Jian Yang wrote:
> Hi Stefan, thank you very much for your quick reply. But is it
> possible to get a single combined transformation just like BSpline
> transformation which I can write and read from file?
> 
> Thanks again.
> 
> Jian
> 
> 
> 
> 
> On Thu, Aug 28, 2008 at 12:03 PM, Stefan Klein <s.klein at erasmusmc.nl> wrote:
>> Hi Jian,
>>
>>
>>> I checked the insight journal and find two classes related to my
>>> topic: Combining
>>> Transforms(http://www.insight-journal.org/dspace/view_item.php?itemid=438)
>>> and Serial Transformations
>>> (http://www.insight-journal.org/dspace/view_item.php?itemid=1080).
>>> However it seems both of them doing the transformations in sequence
>>> instead of combining them together to get a final form of
>>> transformation. If the number of the transformations is very big, the
>>> sequence transformation of image will no doubt downgrade the image
>>> qualities.
>> No, this is not true. The image is interpolated only once with these
>> transforms. At every point x, the TransformPoint(x) function of the
>> SerialTransform/CombinationTransform is called, which calls the
>> TransformPoint() functions of the transforms in sequence. When the total
>> transformation is computed, the image value is obtained by interpolated (so,
>> only once). So, the number of transformations has no impact on the image
>> quality.
>>
>> Kind regards,
>> Stefan
>>
>>> Your help will greatly appreciated.
>>>
>>> Jian
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