1. VTK 3D Widgets
Karthik Krishnan
Will Schroeder
Kitware, Inc.

2. Thanks National Library of Medicine / NIH
Dr. Terry Yoo: A2D2 awards (Algorithms, Adaptors, and Data Distribution)
National Science Foundation
Visual Journal project
NIH National Center for Biomedical Computing
NAMIC
DOE National Labs
Sandia
Livermore
Contributors
Will Schroeder
Karthik Krishnan
Lisa Avila
Brad King
Sebastien Barre
Dave Cole

3. Goals Directly interact with data
Provide complex, potentially 3D interaction techniques
Probing
Annotation
Measurements

4. Interactor styles Render()
Everybody has their favorite way of interacting with Data.
User Events
RenderWindow
Interactor
Interactor Style
Events
Actions
vtkCamera
Render()

5. Object Relationships vtkRenderWindowInteractor vtkInteractorObserver
vtkInteractorStyle
vtkAbstractWidget

6. Interactor Styles (contd..)

7. Interactor styles (usage)
Set the interactor style on the Render Window Interactor
vtkInteractorStyleTrackballCamera *style =
vtkInteractorStyleTrackballCamera::New();
renderWindowInteractor -> SetInteractorStyle( style );

8. VTK Widgets

9. VTK - Widgets Widgets are simply Interactive Props
VTK currently has widgets to perform
Measurements
Annotation and Labeling
Segmentation
Registration
Data interaction
Scene parameter manipulation: Light, camera, etc.
Probing underlying data
Timer support
Multiple geometrical representations for the same widget
Reconfigurable key/mouse bindings
Grouping widgets

10. Visualization pipeline

11. Widgets are interactive props
vtkRenderWindow
vtkRenderWindowInteractor
User Interaction
Events
Widget
Manipulate one
or more props
vtkRenderer
Render()
Widget Representation

12. Widgets – Design goals Separate representation from event processing
Support distributed processing (client-server)
Reconfigurable bindings
Support hierarchical use of widgets
Grouping widgets
Timer, Hover support

13. vtkWidgetRepresentation (type of vtkProp)
Widgets Architecture
Behavior
Geometry
RenderWindow
Renderer
Events
Render()
vtkAbstractWidget
vtkWidgetRepresentation (type of vtkProp)

14. One widget, multiple geometries
Behavior
Geometry
vtkPointHandleRepresentation2D
vtkHandleWidget
Run HandleWidget1 and HandleWidget2 – Sphere and Arnie
vtkPointHandleRepresentation3D
vtkSphereHandleRepresentation
vtkPolygonalHandleRepresentation

15. Configurable bindings: Event Translation

16. Event Translation Re-configurable keyboard/mouse bindings Example:
vtkWidgetEventTranslator *eventTranslator = widget->GetEventTranslator();
eventTranslator->SetTranslation(
vtkCommand::MiddleButtonPressEvent,
vtkWidgetEvent::Select );
vtkCommand::MiddleButtonReleaseEvent,
vtkWidgetEvent::EndSelect );
Run ContourWidget5.sh

17. Widget Assemblies
Create composite widgets from several individual widgets
Children listen to events from Parent. Hence parent can alter behavior of child
RenderWindow
Events
Parent
Events
Events
Child
Child

18. Widget Assemblies Line Widget HandleWidget HandleWidget Code reuse
Component framework:
Change behaviour / geometry of Line widget by changing the handle widgets.
Run the Line widget
Line Widget
HandleWidget
HandleWidget

19. Timer support Widgets may respond to timers Hover widget
Balloon widget
Timer based hover annotations, Popups (text, thumbnails etc).
Run the BalloonWidget

20. Handle Framework
Handles are often fundamental building blocks of other widgets
vtkLineWidget2
vtkDistanceWidget
vtkAngleWidget
vtkBiDimensionalWidget
vtkSeedWidget
vtkParallelopipedWidget
Need multiple representations for handles
Need a framework for constraints on handles
To plane
To surface
To a terrain
To a region.
Run the Line widget

21. Various handle representations (geometries)
vtkPointHandleRepresentation2D
vtkHandleWidget
Run HandleWidget1 and HandleWidget2 – Sphere and Arnie
vtkPointHandleRepresentation3D
vtkSphereHandleRepresentation
vtkPolygonalHandleRepresentation

22. Constraints – Point Placers
To map 2D display positions to 3D world coordinates. Does a 2D display position map to:
Focal Plane ?
Point on a surface ?
Point on a plane / image ?
Out of bounds ?
Allows a variety of constraints to be placed the placement of widgets.

23. Widgets
Handles

24. Widgets (cont.) vtkSliderWidget 2D 3D vtkBorderWidget
Widgets with rectangular borders
vtkTextWidget
Position & size text

25. Widgets (cont.)
BalloonWidget
Text and/or image in rectangular popup

26. Widgets (cont.) vtkCameraWidget Keyframe & playback camera
vtkCaptionWidget
Text with leader

27. Widgets (cont.) vtkCheckerboardWidget Interleave two images
vtkRectilinearWipeWidget
Window pane (2x2 checkerboard) with movable focus

28. Widgets (cont.) vtkContourWidget 2D (on plane)
3D (move contours through slices in a volume)

29. Widgets (cont.) vtkDistanceWidget Measure distance between points
vtkAngleWidget
Measure angles

30. Widgets (cont.) vtkSeedWidget Add one or more seeds / markers
vtkAffineWidget
Translate
Scale
Rotate
Shear images

31. Widgets (cont.)
vtkBiDimensionalWidget
Tumor response (RECIST vs WHO)

32. Widgets (cont.)
Box
Implicit Plane

33. Widgets (cont.)
Finite Plane
Line

34. Widgets (cont.)
vtkSphereWidget
vtkScalarBarWidget

35. Slider Widget Example
vtkSliderRepresentation2D *sliderRep = vtkSliderRepresentation2D::New();
sliderRep->SetValue(0.25);
sliderRep->SetTitleText("Spike Size");
sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedDisplay();
sliderRep->GetPoint1Coordinate()->SetValue(0.2,0.15);
sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedDisplay();
sliderRep->GetPoint2Coordinate()->SetValue(0.8,0.15);
sliderRep->SetSliderLength(0.02);
sliderRep->SetSliderWidth(0.03);
sliderRep->SetEndCapLength(0.01);
sliderRep->SetEndCapWidth(0.03);
sliderRep->SetTubeWidth(0.005);
vtkSliderWidget *sliderWidget = vtkSliderWidget::New();
sliderWidget->SetInteractor(iren);
sliderWidget->SetRepresentation(sliderRep);
sliderWidget->SetAnimationModeToAnimate();
vtkSlider2DCallback *callback = vtkSlider2DCallback::New();
callback->Glyph = glyph;
sliderWidget->AddObserver(vtkCommand::InteractionEvent,callback);

36. Slider Widget Example (Cont.)
class vtkSlider2DCallback : public vtkCommand {
public:
static vtkSlider2DCallback *New()
{ return new vtkSlider2DCallback; }
virtual void Execute(vtkObject *caller, unsigned long, void*)
vtkSliderWidget *sliderWidget =
reinterpret_cast<vtkSliderWidget*>(caller);
this->Glyph->SetScaleFactor(static_cast<vtkSliderRepresentation *>(sliderWidget->GetRepresentation())->GetValue()); }
vtkSlider2DCallback():Glyph(0) {}
vtkGlyph3D *Glyph; };

37. vtkPointPlacer

38. Widget Sets Event RenderWindow Widget Event RenderWindow Widget
Grouping widgets on multiple render windows, relieving the application of the responsibility of doing so.
Event
RenderWindow
Widget
Event
Run PaintbrushExample3, then run PaintbrushExample6 to show that operations may be performed that use run algorithms real-time
Event
RenderWindow
Event
Widget
WidgetSet
Event
RenderWindow
Widget
Event