[IGSTK-Developers] Re: igstkTransfrom documentation update & Style problems

[Luis Ibanez]

Hi Ziv,

Again, the problem with setting them separately is that the time stamp is
shared.

The second setting will override the time stamp of the first setting and the
Transform
will end up with a Translation component that does not match in time to the
Rotation
component.

E.g. the Translation component may even have expired, and by setting only
the
Rotation we will extend its validity time artificially.  It is like making a
sandwich with
fresh cheese and an expired ham.... the cheese may be good, but the total
sandwich
has gone bad anyways.

If the pivot calibration is computing both components separately, then they
should only
be stored in an igstkTransform when both Translation and Rotation are
available, and that
should be done using the SetRotationAndTranslation() method.


   Luis


----------------------------------------------------------------------------
On 8/6/07, Ziv Yaniv <zivy at isis.georgetown.edu> wrote:
>
> Hi Luis,
>
> Setting rotation and translation separately without resetting the
> transformation is reasonable behavior. Pivot calibration for example only
> sets the translational part of a transformation. The user can set the
> rotational part after they get the transformation from the pivot calibration
> according to prior knowledge (what Patrick is doing right now). Of course
> there are many ways to do this (composing separate rotation and translation
> transformations to get a single transform, or setting the transformation
> only when you have both rotation and translation in hand).
>
> In any case I view this as an arbitrary choice and my only preference is
> that the documentation and implementation match.
>
>
>              Ziv
>
>
>
> -----Original Message-----
> From: "Luis Ibanez" <luis.ibanez at kitware.com>
> Sent 8/6/2007 12:41:56 PM
> To: "'Ziv Yaniv'" <zivy at isis.imac.georgetown.edu>, "IGSTK Developers" <
> igstk-developers at public.kitware.com>
> Subject: igstkTransfrom documentation update & Style problems
>
> Hi Ziv,
>
> Thanks for updating the documentation of the Transform class:
> http://public.kitware.com/cgi-bin/viewcvs.cgi/Source/igstkTransform.h?root=IGSTK&sortby=date&r2=1.20&r1=1.19
>
> Unfortunately they introduced several coding style violations.http://public.kitware.com/IGSTK/Sites/insight.journal.kitware/KWStyle/20070806-0430-Nightly/BuildError.html
>
> Also, I'm not sure that the right thing was to modify the documentation.
> It seems that the SetRotation method actually has the bug of not setting
> the translation to identity, and the SetTranslation() method has the bug
> of not setting the rotation to identity.
>
> This should be necessary because the transform has a single TimeStamp,
> and we assume that it is the same for both Translation and Rotation.
>
> I'll suggest that we put the documentation back, and fix the bug in
> the implementation of the methods.
>
> Do you see a reason why not initialized Translation / Rotation may
> bring any advantage ?
>
>
>     Thanks
>
>
>        Luis
>
>
>
>
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