[IGSTK-Developers] Re: itkPivotCallibration

[Hui Zhang]

Hi, Luis,

Thanks a lot for your commenting and help on the code revision. The 
container type from STL has been replaced with ITK container and vector 
type. The vector cross product part is waiting to see whether those will be 
splitted out in a new class. Pls feel free to check the code to see whether 
some other parts need to be updated.

Regards,
James

----- Original Message ----- 
From: "Luis Ibanez" <luis.ibanez at kitware.com>
To: "Hui Zhang" <zhang at isis.imac.georgetown.edu>
Cc: "David Gobbi" <dgobbi at atamai.com>; "IGSTK Developers" 
<igstk-developers at public.kitware.com>
Sent: Thursday, December 08, 2005 2:50 PM
Subject: Re: itkPivotCallibration


>
>   Hi James,
>
>
>   Depending on what operations you to perform in
>   the container, you could use
>
>
>     A) std::vector<> of itk::Versors
>        std::vector<> of itk::Vectors
>
>   or
>
>     B) itk::VectorContainer<> of itk::Versors
>        itk::VectorContainer<> of itk::Vectors
>
>
>
>   Also, you don't need to use vnl_vectors. All vector operations
>   are implemented in itk::Vector. The vnl_matrix can probably be
>   avoided too. We try to stay away from VNL because it breaks the
>   API of ITK.
>
>
>   It will be safer to avoid passing Quaternions as 4 elements.
>   A Quaternion can represent rotations *and scaling*. Only unit
>   quaternions should be used for pure rotations. That's the reason
>   why we use Versors in ITK, since a Versor is a unit Quaternion,
>   and guarrantees to stay that way.
>
>   The code of the PivotCallibration class could be greatly simplified
>   if you use the ITK Vector and Versor classes.
>
>
>   Please let me know if you find problems converting this class
>   to use ITK elements.
>
>
>      Thanks
>
>
>         Luis
>
>
>
> ----------------
> Hui Zhang wrote:
>> Hi, Luis,
>>
>> I use std::vector<double> as the container for the samples of translation 
>> and rotation.
>>
>>  typedef std::vector< double >           InputContainerType;
>> .....
>>  /** Container to save the samples */
>>  InputContainerType    m_Quaternion[4];
>>  InputContainerType    m_Translation[3];
>>
>> That typedef std::vector< double > is only for the one element of 
>> Quaternion or Vector, so that there have four containers for Quaternion 
>> and three containers for Vector. My orginal code only makes use of VNL, 
>> and is not from ITK layer, so I use STL instead. I know that ITK has 
>> Versor and Vector type, but I am not sure whether ITK provides the 
>> container for them, eg, an array of Versors or Vectors and the size can 
>> be dynamically changed. If ITK has them, I can definitely try to change 
>> this from STL to ITK.
>>
>> Thanks,
>> James
>>
>> ----- Original Message ----- From: "Luis Ibanez" 
>> <luis.ibanez at kitware.com>
>> To: "Hui Zhang" <zhang at isis.imac.georgetown.edu>
>> Cc: "David Gobbi" <dgobbi at atamai.com>; "IGSTK Developers" 
>> <igstk-developers at public.kitware.com>
>> Sent: Thursday, December 08, 2005 2:03 PM
>> Subject: itkPivotCallibration
>>
>>
>>>
>>> Hi James,
>>>
>>> I'm looking at the PivotCallibration class and was
>>> wondering why you are using std::vector<double>
>>> for representing Quaternions and Vectors.
>>>
>>> ITK already provide you with Vectors and Versor
>>> classes that you could use here.
>>>
>>> Is there any particular reason why you decided to
>>> use the std::vector<>  instead of ITK classes ?
>>>
>>>
>>>  Please let me know,
>>>
>>>
>>>      Thanks
>>>
>>>
>>>        Luis
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>
>
>