WebcamHeadTracker Class Reference

Webcam-based head tracker. More...

Public Types
enum	DebugOption { Debug_Window = 1, Debug_Timing = 2 }
	Debug options. More...
enum	Filter { Filter_None, Filter_Kalman, Filter_Double_Exponential }
	Filter types. More...

Public Member Functions
	WebcamHeadTracker (unsigned int debugOptions=0)
	Constructor. More...
	~WebcamHeadTracker ()
	Destructor. More...
bool	initWebcam ()
	Initialize the webcam. More...
bool	initPoseEstimator (const char *frontalFaceXml=filePathFrontalFaceXml(), const char *faceLandmarksDat=filePathFaceLandmarksDat())
	Initialize the pose estimator. More...
void	setFocalLengthsInPixels (float fx, float fy)
	Set intrinsic camera parameters: focal lengths. More...
void	setPrincipalPointInPixels (float cx, float cy)
	Set intrinsic camera parameters: principal points. More...
void	setDistortionCoefficients (float k1, float k2, float p1, float p2, float k3=0.0f)
	Set camera distortion coefficients. More...
void	setFilter (enum Filter filter)
	Set the filter that is applied to the pose. More...
bool	isReady () const
	Returns true if this tracker is ready to get a new frame and compute a new head pose. More...
void	getNewFrame ()
	Get a new frame from the webcam. More...
bool	computeHeadPose ()
	Compute a new head pose. More...
void	getHeadPosition (float *headPosition) const
	Get the last known head position. More...
void	getHeadOrientation (float *headOrientation) const
	Get the last known head orientation. More...

Static Public Member Functions
static const char *	filePathFrontalFaceXml ()
	Default path to haarcascade_frontalface_alt.xml (location at build time, if it was found) More...
static const char *	filePathFaceLandmarksDat ()
	Default path to shape_predictor_68_face_landmarks.dat (location at build time, if it was found) More...

Detailed Description

Webcam-based head tracker.

Member Enumeration Documentation

DebugOption

enum WebcamHeadTracker::DebugOption

Debug options.

Enumerator
Debug_Window	Show a GUI window with the webcam frame and face detection results.
Debug_Timing	Print timings for each step to stderr.

Filter

enum WebcamHeadTracker::Filter

Filter types.

Enumerator
Filter_None	Do not apply any filtering (very strong jittering, but no additional delays)
Filter_Kalman	Apply Kalman filter (smooth results, but long update delays on pose changes)
Filter_Double_Exponential	Apply double exponential smoothing (smooth results, acceptable delays)

Constructor & Destructor Documentation

WebcamHeadTracker()

WebcamHeadTracker::WebcamHeadTracker

(

unsigned int

debugOptions = 0

)

Constructor.

Parameters

debugOptions

Bitwise combination of DebugOption flags.

~WebcamHeadTracker()

WebcamHeadTracker::~WebcamHeadTracker

(

)

Destructor.

Member Function Documentation

computeHeadPose()

bool WebcamHeadTracker::computeHeadPose

(

)

Compute a new head pose.

This works on the latest available webcam frame. If head pose estimation fails for some reason (e.g. no face could be found), then this function returns false.

filePathFaceLandmarksDat()

static const char* WebcamHeadTracker::filePathFaceLandmarksDat ( )

static

Default path to shape_predictor_68_face_landmarks.dat (location at build time, if it was found)

filePathFrontalFaceXml()

static const char* WebcamHeadTracker::filePathFrontalFaceXml ( )

static

Default path to haarcascade_frontalface_alt.xml (location at build time, if it was found)

getHeadOrientation()

void WebcamHeadTracker::getHeadOrientation

(

float *

headOrientation

)

const

Get the last known head orientation.

Returns the last known head orientation as a quaternion (x, y, z, w).

The head reference point is the center between the left and right eyes. The coordinate system is the usual system in computer graphics: y points upwards, x points to the right, and the user looks along -z (towards the webcam).

getHeadPosition()

void WebcamHeadTracker::getHeadPosition

(

float *

headPosition

)

const

Get the last known head position.

Returns the last known head orientation as a vector (x, y, z).

The head reference point is the center between the left and right eyes. The coordinate system is the usual system in computer graphics: y points upwards, x points to the right, and the user looks along -z (towards the webcam).

getNewFrame()

void WebcamHeadTracker::getNewFrame

(

)

Get a new frame from the webcam.

initPoseEstimator()

bool WebcamHeadTracker::initPoseEstimator	(	const char *	frontalFaceXml = filePathFrontalFaceXml(),
		const char *	faceLandmarksDat = filePathFaceLandmarksDat()
	)

Initialize the pose estimator.

Parameters

frontalFaceXml	Full path to the file haarcascade_frontalface_alt.xml from OpenCV
faceLandmarksDat	Full path to the file shape_predictor_68_face_landmarks.dat from dlib

This function loads the two data files from OpenCV and dlib. It returns false if this fails. The default parameters should work fine on development systems and Linux(ish) systems, but you might want to bundle these files with your application and use custom file paths as parameters to this function.

initWebcam()

bool WebcamHeadTracker::initWebcam

(

)

Initialize the webcam.

Tries to use the first camera that OpenCV detects. If this fails, no usable webcam is available.

isReady()

bool WebcamHeadTracker::isReady ( ) const

inline

Returns true if this tracker is ready to get a new frame and compute a new head pose.

This returns true once the tracker is successfully initialized. When Debug_Window is set, this can change to false when the user presses 'ESC'.

setDistortionCoefficients()

void WebcamHeadTracker::setDistortionCoefficients	(	float	k1,
		float	k2,
		float	p1,
		float	p2,
		float	k3 = 0.0f
	)

Set camera distortion coefficients.

Parameters

k1	Parameter k1
k2	Parameter k2
p1	Parameter p1
p2	Parameter p2
k3	Parameter k3

Calling this function is optional, the defaults should be ok. To find correct values for your webcam, you need to calibrate it. See OpenCV documentation.

setFilter()

void WebcamHeadTracker::setFilter

(

enum Filter

filter

)

Set the filter that is applied to the pose.

Parameters

filter

The filter

The default is Filter_Double_Exponential.

setFocalLengthsInPixels()

void WebcamHeadTracker::setFocalLengthsInPixels	(	float	fx,
		float	fy
	)

Set intrinsic camera parameters: focal lengths.

Parameters

fx	Horizontal focal length
fy	Vertical focal length

Calling this function is optional, the defaults should be ok. To find correct values for your webcam, you need to calibrate it. See OpenCV documentation.

setPrincipalPointInPixels()

void WebcamHeadTracker::setPrincipalPointInPixels	(	float	cx,
		float	cy
	)

Set intrinsic camera parameters: principal points.

Parameters

cx	Horizontal principal point
cy	Vertical principal point

Calling this function is optional, the defaults should be ok. To find correct values for your webcam, you need to calibrate it. See OpenCV documentation.

---

The documentation for this class was generated from the following file:

• webcam-head-tracker.hpp