[IGSTK-Developers] calibration (followup to David and James'sdiscussion)

[David Gobbi]

Hui Zhang wrote:

> Hi, David and Ziv,
>
> ----- Original Message ----- From: "Ziv Yaniv" 
> <zivy at isis.imac.georgetown.edu>
> To: "David Gobbi" <dgobbi at atamai.com>
> Cc: "'IGSTK-developers'" <igstk-developers at public.kitware.com>
> Sent: Thursday, December 01, 2005 3:56 PM
> Subject: Re: [IGSTK-Developers] calibration (followup to David and 
> James'sdiscussion)
>
>
>> David Gobbi wrote:
>>  ...
>>
>>> The easiest way to do this, though I know James doesn't like it, is 
>>> to have a SetToolOrientation() method in the ToolTipCalibration.  
>>> The tip
>>
>
> I am OK with it, don't worry about me. :) I can add the 
> SetToolOrientation method to the PivotCalibration class and make it an 
> easy way to give the full calibration transform. This routine will be 
> easily accepted by application developer to make the elegent code. I 
> agreed with this. Maybe in the document, we should remind the users 
> that pivot calibration can only provide 3D translation, and the 
> rotation information is set by themselves, to avoid they take the 
> default rotation information as the real rotation elements.

We will need intuitive methods for setting the orientation, because not 
many people are familiar enough with quaternions.  So there could be two 
methods:

 SetToolPrincipalAxis(vx, vy, vz) -- set a vector that points along the 
tool axis towards the tool top
 SetToolFaceNormal(nx, ny, nz) -- set a vector to define a  that "face" 
of the tool, this vector must be perpendicular to the tool axis

The "tool face" is for when you want to use a pointer as a virtual 
ultrasound probe, it will define the orientation of the plane that you 
want to use as the virtual ultrasound plane.  This is only useful for 
6DOF tools, not for 5DOF tools.

These two vectors can be put together to create the quaternion that is 
used as the orientation.  The NDI tool architect software does something 
very similar to this.

 - David