[vtkusers] vtkImagePlaneWidget: how to update plane's orientation?

[Darshan Pai]

I think you need to normalize v2 before you compose the transform

Sent from my iPad

On Mar 23, 2012, at 3:09 PM, Miguel Sotaquirá <msotaquira at gmail.com> wrote:

> Hi again,
> 
> So I've managed to rotate the plane widget 90 degrees (see code below) but somehow the rotated plane is not located on the center of the 3D volume. In the code below I define the origin of the plane widget (wc) as the center of the volume in x,y,z coordinates. I don't know if I'm not defining correctly this center or the transformation (or both?)
> 
> How can I ensure that the center of the plane matches the center of the volume?
> 
> Thanks,
> Miguel
> 
> // Get volume's center
> vtkSmartPointer<vtkImageData> imageData = this->planeWidget[whichPlane]->GetResliceOutput();
> double spacing[3];
> imageData->GetSpacing(spacing);
> double origin[3];
> imageData->GetOrigin(origin);
> int extent[6];
> imageData->GetWholeExtent(extent);
> 	
> // Define widget's center as the center of the volume
> double wc[3];
> wc[0] = origin[0] + 0.5 * spacing[0] * ( extent[0] + extent[1] );
> wc[1] = origin[1] + 0.5 * spacing[1] * ( extent[2] + extent[3] );
> wc[2] = origin[2] + 0.5 * spacing[2] * ( extent[4] + extent[5] );
> 	
> // planeWidget's vector 2 (used as the axis of rotation)
> double v2[3];
> this->planeWidget[whichPlane]->GetVector2(v2);
> 	
> // Transform
> vtkSmartPointer<vtkTransform> transform = vtkSmartPointer<vtkTransform>::New();
> transform->PreMultiply();
> transform->Translate(wc[0],wc[1],wc[2]);
> transform->RotateWXYZ(90,v2[0],v2[1],v2[2]);
> transform->Translate(-wc[0],-wc[1],-wc[2]);
> 	
> // Modify and update planeWidget
> double newpt[3];
> transform->TransformPoint(this->planeWidget[whichPlane]->GetPoint1(),newpt);
> this->planeWidget[whichPlane]->SetPoint1(newpt);
> transform->TransformPoint(this->planeWidget[whichPlane]->GetPoint2(),newpt);
> this->planeWidget[whichPlane]->SetPoint2(newpt);
> transform->TransformPoint(this->planeWidget[whichPlane]->GetOrigin(),newpt);
> this->planeWidget[whichPlane]->SetOrigin(newpt);
> 	
> planeWidget[whichPlane]->UpdatePlacement();
> 
> 
> 
> 2012/3/23 Miguel Sotaquirá <msotaquira at gmail.com>
> Hi everybody!
> 
> I've implemented a four pane viewer using the example found at Examples/GUI/Qt/FourPaneViewer/QtVTKRenderWindows.cxx. This viewer allows me to explore a 3-D volume using a set of three vtkImagePlaneWidgets that can be interactively placed (translated, rotated) by the user using mouse events.
> 
> What I want to do now after user interaction is to take one of these planes and rotate it 90 degrees along its normal, and update the four panes accordingly. In order to do so I'm using this workflow:
> 
> - Define a vtkTransform (transform) and SetMatrix as vtkImagePlaneWidget's current orientation: 
>     vtkSmartPointer<vtkTransform> transform = vtkSmartPointer<vtkTransform>::New();
>     transform->PreMultiply();
>     transform->SetMatrix(planeWidget->GetResliceAxes());
> 
> - Apply 90 degrees rotation around Y axis:
>     transform->RotateY(90);
> 
> - Update planeWidget using methods SetOrigin, SetPoint1, SetPoint2 and UpdatePlacement, where origin, point1, point2 are extracted from "transform"
> 
> When using this approach I get strange results: neither planeWidget's origin nor its extension are well defined, and I'm not able to update the four panes accordingly. The origin is located outside the 3-D volume, and the extension does not cover the entire volume.
> 
> Am I missing something? How to correctly update planeWidget's orientation? Thanks for your help,
> 
> Miguel
> 
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