VTK 3D Widgets Karthik Krishnan Will Schroeder Kitware, Inc

VTK 3D Widgets

Karthik KrishnanKarthik KrishnanWill SchroederWill SchroederKitware, Inc.Kitware, Inc.

ThanksThanks

• 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

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GoalsGoals

• Directly interact with data

• Provide complex, potentially 3D interaction techniques• Probing• Annotation• Measurements

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Interactor stylesInteractor styles

• Everybody has their favorite way of interacting with Data.

RenderWindow

User Events

Interactor Interactor StyleEvents

vtkCamera

Actions

Render()

Object RelationshipsObject Relationships

vtkInteractorObserver

vtkInteractorStyle vtkAbstractWidget

vtkRenderWindowInteractor

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Interactor Styles (contd..)Interactor Styles (contd..)

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Interactor styles (usage)Interactor styles (usage)

• Set the interactor style on the Render Window Interactor

vtkInteractorStyleTrackballCamera *style =

vtkInteractorStyleTrackballCamera::New();

renderWindowInteractor -> SetInteractorStyle( style );

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VTK Widgets

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VTK - WidgetsVTK - 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

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Visualization pipelineVisualization pipeline

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vtkRenderWindow

Widget

User Interaction Events

vtkRenderWindowInteractor

Widgets are interactive propsWidgets are interactive props

vtkRendererRender()

Manipulate oneor more props

Widget Representation

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Widgets – Design goalsWidgets – Design goals

• Separate representation from event processing• Support distributed processing (client-server)

• Reconfigurable bindings

• Support hierarchical use of widgets

• Grouping widgets

• Timer, Hover support

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RenderWindow

vtkAbstractWidget vtkWidgetRepresentation(type of vtkProp)

Events

Renderer

Render()

Widgets ArchitectureWidgets Architecture

Behavior Geometry

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One widget, multiple geometriesOne widget, multiple geometries

vtkHandleWidget vtkPointHandleRepresentation2D

vtkPointHandleRepresentation3D

vtkSphereHandleRepresentation

vtkPolygonalHandleRepresentation

Behavior Geometry

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Configurable bindings: Event TranslationConfigurable bindings: Event Translation

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Event TranslationEvent Translation

• Re-configurable keyboard/mouse bindings

• Example:

vtkWidgetEventTranslator *eventTranslator = widget->GetEventTranslator();

eventTranslator->SetTranslation( vtkCommand::MiddleButtonPressEvent,

vtkWidgetEvent::Select );

eventTranslator->SetTranslation( vtkCommand::MiddleButtonReleaseEvent,

vtkWidgetEvent::EndSelect );

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Widget AssembliesWidget Assemblies

• Create composite widgets from several individual widgets

• Children listen to events from Parent. Hence parent can alter behavior of child

Parent

Child Child

RenderWindowEvents

EventsEvents

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Widget AssembliesWidget Assemblies

• Code reuse

• Component framework: • Change behaviour / geometry of Line widget by changing the

handle widgets.

HandleWidgetHandleWidget

Line Widget

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Timer supportTimer support

• Widgets may respond to timers

• Hover widget• Balloon widget• Timer based hover annotations, Popups (text, thumbnails etc).

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Handle FrameworkHandle 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.

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Various handle representations (geometries)Various handle representations (geometries)

vtkHandleWidget vtkPointHandleRepresentation2D

vtkPointHandleRepresentation3D

vtkSphereHandleRepresentation

vtkPolygonalHandleRepresentation

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Constraints – Point PlacersConstraints – 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.

WidgetsWidgets

• Handles

Widgets (cont.)Widgets (cont.)

• vtkSliderWidget• 2D• 3D

• vtkBorderWidget• Widgets with

rectangular borders

• vtkTextWidget• Position & size text


• BalloonWidget• Text and/or image in rectangular popup


• vtkCameraWidget• Keyframe &

playback camera

• vtkCaptionWidget• Text with leader


• vtkCheckerboardWidget• Interleave two images

• vtkRectilinearWipeWidget• Window pane

(2x2 checkerboard)with movable focus


• vtkContourWidget• 2D (on plane)• 3D (move contours through slices in a volume)


• vtkDistanceWidget• Measure distance

between points

• vtkAngleWidget• Measure angles


• vtkSeedWidget• Add one or more

seeds / markers

• vtkAffineWidget• Translate• Scale• Rotate• Shear images


• vtkBiDimensionalWidget• Tumor response (RECIST vs WHO)


• Box • Implicit Plane


• Finite Plane • Line


• vtkScalarBarWidget• vtkSphereWidget

Slider Widget ExampleSlider 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);

Slider Widget Example (Cont.)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;

};

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vtkPointPlacervtkPointPlacer

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Widget SetsWidget Sets

• Grouping widgets on multiple render windows, relieving the application of the responsibility of doing so.

RenderWindowEvent

Widget

RenderWindowEvent

Widget

RenderWindowEvent

Widget

WidgetSetEvent

Event

Event

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VTK 3D Widgets Karthik Krishnan Will Schroeder Kitware, Inc