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# Viz

This section describes 3D visualization window as well as classes and methods that are used to interact with it.

3D visualization window (see `Viz3d`) is used to display widgets (see `Widget`), and it provides several methods to interact with scene and widgets.

## viz::makeTransformToGlobal

Takes coordinate frame data and builds transform to global coordinate frame.

C++:`` Affine3d `viz::``makeTransformToGlobal`(const Vec3f& axis_x, const Vec3f& axis_y, const Vec3f& axis_z, const Vec3f& origin=Vec3f::all(0))

  Parameters: | axis_x – X axis vector in global coordinate frame. axis_y – Y axis vector in global coordinate frame. axis_z – Z axis vector in global coordinate frame. origin – Origin of the coordinate frame in global coordinate frame.

This function returns affine transform that describes transformation between global coordinate frame and a given coordinate frame.

## viz::makeCameraPose

Constructs camera pose from position, focal_point and up_vector (see gluLookAt() for more infromation).

C++:`` Affine3d `makeCameraPose`(const Vec3f& position, const Vec3f& focal_point, const Vec3f& y_dir)

  Parameters: | position – Position of the camera in global coordinate frame. focal_point – Focal point of the camera in global coordinate frame. y_dir – Up vector of the camera in global coordinate frame.

This function returns pose of the camera in global coordinate frame.

## viz::getWindowByName

Retrieves a window by its name.

C++:`` Viz3d `getWindowByName`(const String& window_name)

  Parameters: | window_name – Name of the window that is to be retrieved.

This function returns a `Viz3d` object with the given name.

Note

If the window with that name already exists, that window is returned. Otherwise, new window is created with the given name, and it is returned.

Note

Window names are automatically prefixed by “Viz - ” if it is not done by the user.

    /// window and window_2 are the same windows.
    viz::Viz3d window   = viz::getWindowByName("myWindow");
    viz::Viz3d window_2 = viz::getWindowByName("Viz - myWindow");

## viz::isNan

Checks float/double value for nan.

> C++:`` bool `isNan`(float x)
> C++:`` bool `isNan`(double x)

>   Parameters: | x – return true if nan.

Checks vector for nan.

> C++:`` bool `isNan`(const Vec<_Tp, cn>& v)

>   Parameters: | v – return true if any of the elements of the vector is nan.

Checks point for nan

> C++:`` bool `isNan`(const Point3_<_Tp>& p)

>   Parameters: | p – return true if any of the elements of the point is nan.

## viz::Viz3d

class `Viz3d`

The Viz3d class represents a 3D visualizer window. This class is implicitly shared.

    class CV_EXPORTS Viz3d
    {
    public:
        typedef cv::Ptr<Viz3d> Ptr;
        typedef void (*KeyboardCallback)(const KeyboardEvent&, void*);
        typedef void (*MouseCallback)(const MouseEvent&, void*);

        Viz3d(const String& window_name = String());
        Viz3d(const Viz3d&);
        Viz3d& operator=(const Viz3d&);
        ~Viz3d();

        void showWidget(const String &id, const Widget &widget, const Affine3d &pose = Affine3d::Identity());
        void removeWidget(const String &id);
        Widget getWidget(const String &id) const;
        void removeAllWidgets();

        void setWidgetPose(const String &id, const Affine3d &pose);
        void updateWidgetPose(const String &id, const Affine3d &pose);
        Affine3d getWidgetPose(const String &id) const;

        void showImage(InputArray image, const Size& window_size = Size(-1, -1));

        void setCamera(const Camera &camera);
        Camera getCamera() const;
        Affine3d getViewerPose();
        void setViewerPose(const Affine3d &pose);

        void resetCameraViewpoint (const String &id);
        void resetCamera();

        void convertToWindowCoordinates(const Point3d &pt, Point3d &window_coord);
        void converTo3DRay(const Point3d &window_coord, Point3d &origin, Vec3d &direction);

        Size getWindowSize() const;
        void setWindowSize(const Size &window_size);
        String getWindowName() const;
        void saveScreenshot (const String &file);
        void setWindowPosition (int x, int y);
        void setFullScreen (bool mode);
        void setBackgroundColor(const Color& color = Color::black());

        void spin();
        void spinOnce(int time = 1, bool force_redraw = false);
        bool wasStopped() const;

        void registerKeyboardCallback(KeyboardCallback callback, void* cookie = 0);
        void registerMouseCallback(MouseCallback callback, void* cookie = 0);

        void setRenderingProperty(const String &id, int property, double value);
        double getRenderingProperty(const String &id, int property);

        void setRepresentation(int representation);
    private:
        /* hidden */
    };

## viz::Viz3d::Viz3d

The constructors.

C++:`` `Viz3d::``Viz3d`(const String& window_name=String())

  Parameters: | window_name – Name of the window.

## viz::Viz3d::showWidget

Shows a widget in the window.

C++:`` void `Viz3d::``showWidget`(const String& id, const Widget& widget, const Affine3d& pose=Affine3d::Identity())

  Parameters: | id – A unique id for the widget. widget – The widget to be displayed in the window. pose – Pose of the widget.

## viz::Viz3d::removeWidget

Removes a widget from the window.

C++:`` void `removeWidget`(const String& id)

  Parameters: | id – The id of the widget that will be removed.

## viz::Viz3d::getWidget

Retrieves a widget from the window. A widget is implicitly shared; that is, if the returned widget is modified, the changes will be immediately visible in the window.

C++:`` Widget `getWidget`(const String& id)`const`

  Parameters: | id – The id of the widget that will be returned.

## viz::Viz3d::removeAllWidgets

Removes all widgets from the window.

C++:`` void `removeAllWidgets`()

## viz::Viz3d::showImage

Removed all widgets and displays image scaled to whole window area.

C++:`` void `showImage`(InputArray image, const Size& window_size=Size(-1, -1))

  Parameters: | image – Image to be displayed. size – Size of Viz3d window. Default value means no change.

## viz::Viz3d::setWidgetPose

Sets pose of a widget in the window.

C++:`` void `setWidgetPose`(const String& id, const Affine3d& pose)

  Parameters: | id – The id of the widget whose pose will be set. pose – The new pose of the widget.

## viz::Viz3d::updateWidgetPose

Updates pose of a widget in the window by pre-multiplying its current pose.

C++:`` void `updateWidgetPose`(const String& id, const Affine3d& pose)

  Parameters: | id – The id of the widget whose pose will be updated. pose – The pose that the current pose of the widget will be pre-multiplied by.

## viz::Viz3d::getWidgetPose

Returns the current pose of a widget in the window.

C++:`` Affine3d `getWidgetPose`(const String& id)`const`

  Parameters: | id – The id of the widget whose pose will be returned.

## viz::Viz3d::setCamera

Sets the intrinsic parameters of the viewer using Camera.

C++:`` void `setCamera`(const Camera& camera)

  Parameters: | camera – Camera object wrapping intrinsinc parameters.

## viz::Viz3d::getCamera

Returns a camera object that contains intrinsic parameters of the current viewer.

C++:`` Camera `getCamera`()`const`

## viz::Viz3d::getViewerPose

Returns the current pose of the viewer.

..ocv:function:: Affine3d getViewerPose()

## viz::Viz3d::setViewerPose

Sets pose of the viewer.

C++:`` void `setViewerPose`(const Affine3d& pose)

  Parameters: | pose – The new pose of the viewer.

## viz::Viz3d::resetCameraViewpoint

Resets camera viewpoint to a 3D widget in the scene.

C++:`` void `resetCameraViewpoint`(const String& id)

  Parameters: | pose – Id of a 3D widget.

## viz::Viz3d::resetCamera

Resets camera.

C++:`` void `resetCamera`()

## viz::Viz3d::convertToWindowCoordinates

Transforms a point in world coordinate system to window coordinate system.

C++:`` void `convertToWindowCoordinates`(const Point3d& pt, Point3d& window_coord)

  Parameters: | pt – Point in world coordinate system. window_coord – Output point in window coordinate system.

## viz::Viz3d::converTo3DRay

Transforms a point in window coordinate system to a 3D ray in world coordinate system.

C++:`` void `converTo3DRay`(const Point3d& window_coord, Point3d& origin, Vec3d& direction)

  Parameters: | window_coord – Point in window coordinate system. origin – Output origin of the ray. direction – Output direction of the ray.

## viz::Viz3d::getWindowSize

Returns the current size of the window.

C++:`` Size `getWindowSize`()`const`

## viz::Viz3d::setWindowSize

Sets the size of the window.

C++:`` void `setWindowSize`(const Size& window_size)

  Parameters: | window_size – New size of the window.

## viz::Viz3d::getWindowName

Returns the name of the window which has been set in the constructor.

C++:`` String `getWindowName`()`const`

## viz::Viz3d::saveScreenshot

Saves screenshot of the current scene.

C++:`` void `saveScreenshot`(const String& file)

  Parameters: | file – Name of the file.

## viz::Viz3d::setWindowPosition

Sets the position of the window in the screen.

C++:`` void `setWindowPosition`(int x, int y)

  Parameters: | x – x coordinate of the window y – y coordinate of the window

## viz::Viz3d::setFullScreen

Sets or unsets full-screen rendering mode.

C++:`` void `setFullScreen`(bool mode)

  Parameters: | mode – If true, window will use full-screen mode.

## viz::Viz3d::setBackgroundColor

Sets background color.

C++:`` void `setBackgroundColor`(const Color& color=Color::black())

## viz::Viz3d::spin

The window renders and starts the event loop.

C++:`` void `spin`()

## viz::Viz3d::spinOnce

Starts the event loop for a given time.

C++:`` void `spinOnce`(int time=1, bool force_redraw=false)

  Parameters: | time – Amount of time in milliseconds for the event loop to keep running. force_draw – If true, window renders.

## viz::Viz3d::wasStopped

Returns whether the event loop has been stopped.

C++:`` bool `wasStopped`()

## viz::Viz3d::registerKeyboardCallback

Sets keyboard handler.

C++:`` void `registerKeyboardCallback`(KeyboardCallback callback, void* cookie=0)

  Parameters: | callback – Keyboard callback `(void (*KeyboardCallbackFunction(const KeyboardEvent&, void*))`. cookie – The optional parameter passed to the callback.

## viz::Viz3d::registerMouseCallback

Sets mouse handler.

C++:`` void `registerMouseCallback`(MouseCallback callback, void* cookie=0)

  Parameters: | callback – Mouse callback `(void (*MouseCallback)(const MouseEvent&, void*))`. cookie – The optional parameter passed to the callback.

## viz::Viz3d::setRenderingProperty

Sets rendering property of a widget.

C++:`` void `setRenderingProperty`(const String& id, int property, double value)

  Parameters: | id – Id of the widget. property – Property that will be modified. value – The new value of the property.

  Rendering property can be one of the following:

  - POINT_SIZE

  - OPACITY

  - LINE_WIDTH

  - FONT_SIZE

  - REPRESENTATION: Expected values are
      - REPRESENTATION_POINTS
      - REPRESENTATION_WIREFRAME
      - REPRESENTATION_SURFACE
  - IMMEDIATE_RENDERING:
      - Turn on immediate rendering by setting the value to `1`.
      - Turn off immediate rendering by setting the value to `0`.
  - SHADING: Expected values are
      - SHADING_FLAT
      - SHADING_GOURAUD
      - SHADING_PHONG

## viz::Viz3d::getRenderingProperty

Returns rendering property of a widget.

C++:`` double `getRenderingProperty`(const String& id, int property)

  Parameters: | id – Id of the widget. property – Property.

  Rendering property can be one of the following:

  - POINT_SIZE

  - OPACITY

  - LINE_WIDTH

  - FONT_SIZE

  - REPRESENTATION: Expected values are
      - REPRESENTATION_POINTS
      - REPRESENTATION_WIREFRAME
      - REPRESENTATION_SURFACE
  - IMMEDIATE_RENDERING:
      - Turn on immediate rendering by setting the value to `1`.
      - Turn off immediate rendering by setting the value to `0`.
  - SHADING: Expected values are
      - SHADING_FLAT
      - SHADING_GOURAUD
      - SHADING_PHONG

## viz::Viz3d::setRepresentation

Sets geometry representation of the widgets to surface, wireframe or points.

C++:`` void `setRepresentation`(int representation)

  Parameters: | representation – Geometry representation which can be one of the following: REPRESENTATION_POINTS REPRESENTATION_WIREFRAME REPRESENTATION_SURFACE

## viz::Color

class `Color`

This class a represents BGR color.

    class CV_EXPORTS Color : public Scalar
    {
    public:
        Color();
        Color(double gray);
        Color(double blue, double green, double red);

        Color(const Scalar& color);

        static Color black();
        static Color blue();
        static Color green();
        static Color cyan();

        static Color red();
        static Color magenta();
        static Color yellow();
        static Color white();

        static Color gray();
    };

## viz::Mesh

class `Mesh`

This class wraps mesh attributes, and it can load a mesh from a `ply` file.

    class CV_EXPORTS Mesh
    {
    public:

        Mat cloud, colors, normals;

        //! Raw integer list of the form: (n,id1,id2,...,idn, n,id1,id2,...,idn, ...)
        //! where n is the number of points in the poligon, and id is a zero-offset index into an associated cloud.
        Mat polygons;

        //! Loads mesh from a given ply file
        static Mesh load(const String& file);
    };

## viz::Mesh::load

Loads a mesh from a `ply` file.

C++:`` static Mesh `load`(const String& file)

  Parameters: | file – File name (for no only PLY is supported)

## viz::KeyboardEvent

class `KeyboardEvent`

This class represents a keyboard event.

    class CV_EXPORTS KeyboardEvent
    {
    public:
        enum { ALT = 1, CTRL = 2, SHIFT = 4 };
        enum Action { KEY_UP = 0, KEY_DOWN = 1 };

        KeyboardEvent(Action action, const String& symbol, unsigned char code, int modifiers);

        Action action;
        String symbol;
        unsigned char code;
        int modifiers;
    };

## viz::KeyboardEvent::KeyboardEvent

Constructs a KeyboardEvent.

C++:`` `KeyboardEvent`(Action action, const String& symbol, unsigned char code, Modifiers modifiers)

  Parameters: | action – Signals if key is pressed or released. symbol – Name of the key. code – Code of the key. modifiers – Signals if `alt`, `ctrl` or `shift` are pressed or their combination.

## viz::MouseEvent

class `MouseEvent`

This class represents a mouse event.

    class CV_EXPORTS MouseEvent
    {
    public:
        enum Type { MouseMove = 1, MouseButtonPress, MouseButtonRelease, MouseScrollDown, MouseScrollUp, MouseDblClick } ;
        enum MouseButton { NoButton = 0, LeftButton, MiddleButton, RightButton, VScroll } ;

        MouseEvent(const Type& type, const MouseButton& button, const Point& pointer, int modifiers);

        Type type;
        MouseButton button;
        Point pointer;
        int modifiers;
    };

## viz::MouseEvent::MouseEvent

Constructs a MouseEvent.

C++:`` `MouseEvent`(const Type& type, const MouseButton& button, const Point& p, Modifiers modifiers)

  Parameters: | type – Type of the event. This can be MouseMove, MouseButtonPress, MouseButtonRelease, MouseScrollDown, MouseScrollUp, MouseDblClick. button – Mouse button. This can be NoButton, LeftButton, MiddleButton, RightButton, VScroll. p – Position of the event. modifiers – Signals if `alt`, `ctrl` or `shift` are pressed or their combination.

## viz::Camera

class `Camera`

This class wraps intrinsic parameters of a camera. It provides several constructors that can extract the intrinsic parameters from `field of view`, `intrinsic matrix` and `projection matrix`.

    class CV_EXPORTS Camera
    {
    public:
        Camera(double f_x, double f_y, double c_x, double c_y, const Size &window_size);
        Camera(const Vec2d &fov, const Size &window_size);
        Camera(const Matx33d &K, const Size &window_size);
        Camera(const Matx44d &proj, const Size &window_size);

        inline const Vec2d & getClip() const;
        inline void setClip(const Vec2d &clip);

        inline const Size & getWindowSize() const;
        void setWindowSize(const Size &window_size);

        inline const Vec2d & getFov() const;
        inline void setFov(const Vec2d & fov);

        inline const Vec2d & getPrincipalPoint() const;
        inline const Vec2d & getFocalLength() const;

        void computeProjectionMatrix(Matx44d &proj) const;

        static Camera KinectCamera(const Size &window_size);

    private:
        /* hidden */
    };

## viz::Camera::Camera

Constructs a Camera.

C++:`` `Camera`(double f_x, double f_y, double c_x, double c_y, const Size& window_size)

  Parameters: | f_x – Horizontal focal length. f_y – Vertical focal length. c_x – x coordinate of the principal point. c_y – y coordinate of the principal point. window_size – Size of the window. This together with focal length and principal point determines the field of view.

C++:`` `Camera`(const Vec2d& fov, const Size& window_size)

  Parameters: | fov – Field of view (horizontal, vertical) window_size – Size of the window.

  Principal point is at the center of the window by default.

C++:`` `Camera`(const Matx33d& K, const Size& window_size)

  Parameters: | K – Intrinsic matrix of the camera. window_size – Size of the window. This together with intrinsic matrix determines the field of view.

C++:`` `Camera`(const Matx44d& proj, const Size& window_size)

  Parameters: | proj – Projection matrix of the camera. window_size – Size of the window. This together with projection matrix determines the field of view.

## viz::Camera::computeProjectionMatrix

Computes projection matrix using intrinsic parameters of the camera.

C++:`` void `computeProjectionMatrix`(Matx44d& proj)`const`

  Parameters: | proj – Output projection matrix.

## viz::Camera::KinectCamera

Creates a Kinect Camera.

C++:`` static Camera `KinectCamera`(const Size& window_size)

  Parameters: | window_size – Size of the window. This together with intrinsic matrix of a Kinect Camera determines the field of view.

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