[IGSTK-Users] Tool positions or Tools Translations?

[Jake McIvor]

Hey Eric,

Can you clarify something? Is there any relative motion between your
passive markers, or are they fixed to a rigid body?

If they are fixed like a 'normal' wireless tool, you should be able to
setup your scene graph in IGSTK to match the settings in the .rom
file.  I think you want to use the RequestComputeTransformTo() method
instead of the GetTransform() method.  The argument should be whatever
your reference is (I think you were using a static reference tool).
The GetTransform() method only returns the transform to an objects
parent, which in this case would be your tool, and the transform you
defined.

Although it is possible to get single (stray) marker position data
from Polaris, as others have mentioned, IGSTK doesn't really support
it. I believe the difficulty is because there is no way to keep track
of which marker is which.

So, if you just want to recreate where the markers were as you moved a
wireless tool, you should be able to change your method as above. If
you want to look at the actual positions of the markers, it will be
more difficult.

Hope that helps,

Jake

--
Jake McIvor
MASc Candidate, Biomedical Engineering
University of British Columbia

On 6/29/09, Eric L. B. <eric_lb at hotmail.com> wrote:
>
>
>
>
>
> Hello...
>
> I'm using a NDI Polaris tracking system.
>
> I know that IGSTK is not supported for single markers tracking. Thats why
> i'm looking for another option.
>
> I have a passive tool with three markers. With the tracking system i can get
> the position of one of the spheres, because the origin of the coordinate
> system is exactly in one sphere.
>
> With this information i want to rebuild the position of the other two
> spheres. Graphically, I draw the other two spheres and set observers to each
> sphere. With this, i think i can get the transformations that correspond
> with the real reflective spheres.
>
> Comparing the position returned by the observer of sphere 1 (origin of the
> coordinate) with the information of the tracking of the passive tool, this
> data math. Then i suppose that the other two positions returned by the
> observers for spheres 2 and 3 must match too, but its not true :( There are,
> in the best case, positions not corresponding with the coordinate system,
> they are transformated.
>
> Then, i don't know if i'm using the data correctly. The information of a
> transform returned by the observer is the rotation (GetRotation) and
> translation (GetTranslation) or is the position and rotation.
>
> How can i get the orientation of the tool??
>
>
>
> Regards,
>
> Eric
>
>
>
>
>
> Image Analysis And Visualization Laboratory
> Centro de Ciencias Aplicadas y Desarrollo Tecnologico CCADET UNAM
> Circuito Exterior S/N, Cd. Universitaria,
> AP 70-186, CP 04510 Mexico, DF
> Tel: +(52)(55) 56 22 86 02, ext. 1130
>
>
>
>
>
>
> ***************************************************
>> Date: Mon, 29 Jun 2009 10:17:09 -0400
>> From: zivy at isis.imac.georgetown.edu
>> To: eric_lb at hotmail.com
>> CC: igstk-users at public.kitware.com
>> Subject: Re: [IGSTK-Users] Tool positions or Tools Translations?
>>
>> Hi Eric,
>>
>> Which tracking system are you using?
>>
>> Currently, IGSTK does not support tracking of single markers
>> (MicronTracker's XPoint or NDI's reflective spheres). All tracked
>> objects consist of at least three points, with IGSTK sending the
>> relevant API commands to the tracker based on the assumption that we are
>> tracking a frame (coordinate system).
>>
>> regards
>> Ziv
>>
>> > --
>> Ziv Yaniv, PhD., Research Assistant Professor
>> Imaging Science and Information Systems (ISIS) Center
>> Department of Radiology
>> Georgetown University Medical Center
>> 2115 Wisconsin Avenue, Suite 603
>> Washington, DC, 20007,
>>
>> Phone: +1-202-687-7286
>> Fax: +1-202-784-3479
>> email: zivy at isis.georgetown.edu
>> web: http://isiswiki.georgetown.edu/zivy/
>> > > ------------------------------------------------------------------------
>> >
>> > _______________________________________________
>> > Powered by www.kitware.com
>> >
>> > Visit other Kitware open-source projects at
>> > http://www.kitware.com/opensource/opensource.html
>> >
>> > Follow this link to subscribe/unsubscribe:
>> > http://public.kitware.com/cgi-bin/mailman/listinfo/igstk-users
>>
>>
>
> _________________________________________________________________
> Si no está en Windows Live, nunca pasó
> http://www.actualizatuperfil.com.mx/