[vtkusers] Several point clouds alignment using ICP

[nuno.jf]

Sorry for the delay in my response. Well, this isn't a commercial machine, is
a prototype for a college project. I am rotating around the Y axis, and
translating according to the Z axis.  I think I might have a problem with
the transformation in vtkTransformPolyDataFilter. My camera was located ~875
mm (according to Z axis) away from my camera. Between two consecutive steps
I have a rotation of the object of 6.25º (according to Y axis). I believe
the problem is that I don't consider the translation associated with the X
axis, and, when rotating the 10th image (for example) I have to rotate it
(10-1)*6.25 degrees, and in this case, it might produce a significant error. 
For the calibration of my scanner I used Zhang's method with available
opencv libraries. After calibrating, I get a .xml file (cam_extrinsic.xml)
with the extrinsic parameters of the camera. The content of the file is the
following: 

<?xml version="1.0"?>


2
3
f

-2.00187469e+000 -2.08160806e+000 -5.57140887e-001 -1.59499664e+002
-8.67975845e+001 8.86059509e+002


As the camera's extrinsic parameters stand for rotation and translation
relatively to my object, is there anyway I can get the correct distance and
rotation to apply to vtkTransformPolyDataFilter from this file? 
Can anyone explain me what this numbers exactly are and mean?

That way I could define the correct translation and rotation.

vtkTransformPolyDataFilter *TF = vtkTransformPolyDataFilter::New();
vtkTransform *ActualPosition = vtkTransform::New();

ActualPosition -> Identity();
ActualPosition -> PostMultiply();
ActualPosition -> Translate( 0, 0, -875); // bings the 2º point cloud to
the origin
ActualPosition -> RotateY( 6.25 ); // rotates the 2º point cloud
ActualPosition -> Translate( 0, 0, 875); // places the 2º point cloud back
to where it was

TF -> SetInput( polyData2 );
TF -> SetTransform( ActualPosition );
TF -> Update();


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