[IGSTK-Developers] CylinderSpatialObjectRepresentation

[Patrick Cheng]

I guess David meant the Pointer is pointing towards the -Z direction.
But anyway, only when I remove the '-' sign, that the cylinderObject 
will be on the right side.

The PrincipalAxisCalibration is taking the known principal axis of the 
Spatial Object(cylinder) and Tracker Tool(pointer) in their own 
coordinate system. eg. By default, the cylinder is along it's Y axis, 
and pointer is along its Z axis. The PrincipalAxisCalibration then take 
the two principal axis, and figure out what rotation we need to take to 
align the cylinder with the pointer (in another word, transform the 
cylinder's coordinate system to the pointer's coordinate system).

Julien, I have questions about your approach (add an transform to actor)

1. The final CylinderSpatialObject is actually not carrying the correct 
transform. Only when we visualize it, we add another transform to make 
the actor look right. I believe we should have the CylinderSpatialObject 
transform right instead of altering the actor's transform. suppose we 
need to do path planing or collision detection, we are working with the 
SpatialObject's transform, not the actor's transform.

2. This will conflict with the PrincipalAxisCalibration, as people get 
confused what is the real principal axis is. Here the principal axis for 
the cylinder is still Y, and Pointer is Z. But since we are going to 
have a rotation when we visualize it, we don't need the 
PrincipalAxisCalibration here.

3. maybe we can move the rotation and shift of origin in the 
CylinderSpatialObject class.

Patrick

Julien Jomier wrote:
> Hi Patrick,
> 
> David told me that the cylinder should be located in the [-Z,0], 
> therefore the cylinder should be translated by 
> -m_CylinderSpatialObject->GetHeight()/2.0
> 
>  > One quick question: If we can just change the transform when we create
>  > the actor, what do we need the PrincipalAxisCalibration for?
> 
> I don't know what the PrincipalAxisCalibration class is actually doing, 
> but the user cannot change the actor, so we need a way to calibrate the 
> tool anyway.
> 
> Julien
> 
> Patrick Cheng wrote:
>> Hi Julien,
>>
>> I checked out your recent change in the 
>> CylinderSpatialObjectRepresentation class. Now without setting the 
>> rotation part of the CalibrationTransform, the orientation of the 
>> CylinderObject will be correct, but with one little bug, in line 152 
>> (igstkCylinderObjectRepresentation.cxx)
>> cylinderActor->SetPosition(0,0,-m_CylinderSpatialObject->GetHeight()/2.0); 
>>
>> There should be no '-' sign. I tested it in the application.
>>
>> One quick question: If we can just change the transform when we create 
>> the actor, what do we need the PrincipalAxisCalibration for?
>>
>> Patrick
>>
> 
>