#include <vpDetectorFace.h>

Inheritance diagram for vpDetectorFace:

Public Member Functions
	vpDetectorFace ()
bool	detect (const vpImage< unsigned char > &I) VP_OVERRIDE
bool	detect (const cv::Mat &frame_gray)
void	setCascadeClassifierFile (const std::string &filename)

Protected Attributes
std::vector< cv::Rect >	m_faces
cv::CascadeClassifier	m_face_cascade
cv::Mat	m_frame_gray

Inherited functionalities from vpDetectorBase
std::vector< std::vector< vpImagePoint > >	m_polygon
std::vector< std::string >	m_message
size_t	m_nb_objects
unsigned long	m_timeout_ms
vpRect	getBBox (size_t i) const
vpImagePoint	getCog (size_t i) const
std::vector< std::string > &	getMessage ()
std::string &	getMessage (size_t i)
size_t	getNbObjects () const
std::vector< std::vector< vpImagePoint > > &	getPolygon ()
std::vector< vpImagePoint > &	getPolygon (size_t i)
void	setTimeout (unsigned long timeout_ms)

Detailed Description

The vpDetectorFace class is a wrapper over OpenCV Haar cascade face detection capabilities. To use this class ViSP should be build against OpenCV 2.2.0 or a more recent version. Installation instructions are provided here https://visp.inria.fr/3rd_opencv.

The following sample code shows how to use this class to detect the largest face in the image. The cascade classifier file "haarcascade_frontalface_alt.xml" can be found in ViSP source code or in OpenCV.

#include <visp3/detection/vpDetectorFace.h>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
int main()
{
#if defined(VISP_HAVE_OPENCV) && defined(HAVE_OPENCV_OBJDETECT)
  vpImage<unsigned char> I;
  vpDetectorFace face_detector;
  face_detector.setCascadeClassifierFile("haarcascade_frontalface_alt.xml");
 
  while(1) {
    // Acquire a new image in I
    bool face_found = face_detector.detect(I);
    if (face_found) {
      vpRect face_bbox = face_detector.getBBox(0); // largest face has index 0
    }
  }
#endif
}

Tutorials & Examples

Tutorials
If you want a more complete example that works with images acquired from a camera, you may have a look at:

Tutorial: Face detection

Examples: tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 101 of file vpDetectorFace.h.

Constructor & Destructor Documentation

◆ vpDetectorFace()

BEGIN_VISP_NAMESPACE vpDetectorFace::vpDetectorFace ( )

Default constructor.

Definition at line 52 of file vpDetectorFace.cpp.

References m_face_cascade, m_faces, and m_frame_gray.

Member Function Documentation

◆ detect() [1/2]

bool vpDetectorFace::detect ( const cv::Mat & frame_gray )

Allows to detect a face in the image. When more than one face is detected, faces are sorted from largest to smallest.

Parameters

frame_gray : Input gray level image to process.

Returns: true if one or more faces are found, false otherwise.

The number of detected faces is returned using getNbObjects(). If a face is found the functions getBBox(), getCog() return some information about the location of the face.

The largest face is always available using getBBox(0) or getCog(0).

Definition at line 103 of file vpDetectorFace.cpp.

References m_face_cascade, m_faces, vpDetectorBase::m_message, vpDetectorBase::m_nb_objects, and vpDetectorBase::m_polygon.

Referenced by visp.python.rbt.xfeat.XFeatTrackingBackend.XFeatTrackingBackend::process_frame().

◆ detect() [2/2]

bool vpDetectorFace::detect ( const vpImage< unsigned char > & I )

virtual

Allows to detect a face in the image. When more than one face is detected, faces are sorted from largest to smallest.

Parameters

I	: Input image to process. This ViSP image is converted internally in an OpenCV cv::Mat image. If you original image is an gray level OpenCV image, we suggest rather the use of detect(const cv::Mat &).

Returns: true if one or more faces are found, false otherwise.

The number of detected faces is returned using getNbObjects(). If a face is found the functions getBBox(), getCog() return some information about the location of the face.

The largest face is always available using getBBox(0) or getCog(0).

See also: detect(const cv::Mat &)

Implements vpDetectorBase.

Examples: tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 84 of file vpDetectorFace.cpp.

References vpImageConvert::convert(), detect(), and m_frame_gray.

Referenced by detect(), and visp.python.rbt.xfeat.XFeatTrackingBackend.XFeatTrackingBackend::process_frame().

◆ getBBox()

vpRect vpDetectorBase::getBBox ( size_t i ) const

inherited

Return the bounding box of the ith object.

Examples: tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 92 of file vpDetectorBase.cpp.

References m_polygon.

Referenced by detect().

◆ getCog()

vpImagePoint vpDetectorBase::getCog ( size_t i ) const

inherited

Return the center of gravity location of the ith object.

Examples: servoBiclopsPoint2DArtVelocity.cpp, servoPololuPtuPoint2DJointVelocity.cpp, and tutorial-flir-ptu-ibvs.cpp.

Definition at line 78 of file vpDetectorBase.cpp.

References m_polygon.

Referenced by detect().

◆ getMessage() [1/2]

std::vector< std::string > & vpDetectorBase::getMessage ( )

inlineinherited

Returns the contained message of the ith object if there is one.

Examples: catchAprilTag.cpp, catchArUco.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 98 of file vpDetectorBase.h.

References m_message.

◆ getMessage() [2/2]

std::string & vpDetectorBase::getMessage ( size_t i )

inherited

Returns the contained message of the ith object if there is one.

Definition at line 64 of file vpDetectorBase.cpp.

References vpException::badValue, m_message, and m_polygon.

◆ getNbObjects()

size_t vpDetectorBase::getNbObjects ( ) const

inlineinherited

Return the number of objects that are detected.

Examples: catchAprilTag.cpp, catchArUco.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, tutorial-face-detector-live.cpp, tutorial-face-detector.cpp, tutorial-flir-ptu-ibvs.cpp, tutorial-mb-generic-tracker-apriltag-rs2.cpp, tutorial-mb-generic-tracker-apriltag-webcam.cpp, and tutorial-pose-from-qrcode-image.cpp.

Definition at line 108 of file vpDetectorBase.h.

References m_nb_objects.

◆ getPolygon() [1/2]

std::vector< std::vector< vpImagePoint > > & vpDetectorBase::getPolygon ( )

inlineinherited

Returns object container box as a vector of points.

Examples: catchAprilTag.cpp, tutorial-barcode-detector-live.cpp, tutorial-barcode-detector.cpp, and tutorial-pose-from-qrcode-image.cpp.

Definition at line 113 of file vpDetectorBase.h.

References m_polygon.

◆ getPolygon() [2/2]

std::vector< vpImagePoint > & vpDetectorBase::getPolygon ( size_t i )

inherited

Returns ith object container box as a vector of points.

Definition at line 50 of file vpDetectorBase.cpp.

References vpException::badValue, and m_polygon.

◆ setCascadeClassifierFile()

void vpDetectorFace::setCascadeClassifierFile ( const std::string & filename )

Set the name of the OpenCV cascade classifier file used for face detection.

Parameters

filename : Full path to access to the file. Such a file can be found in OpenCV. Within the last versions it was name "haarcascade_frontalface_alt.xml".

Examples: tutorial-face-detector-live-threaded.cpp, tutorial-face-detector-live.cpp, and tutorial-face-detector.cpp.

Definition at line 60 of file vpDetectorFace.cpp.

References vpException::ioError, and m_face_cascade.

◆ setTimeout()

void vpDetectorBase::setTimeout ( unsigned long timeout_ms )

inlineinherited

Set detector timeout in milli-seconds. When set to 0, there is no timeout.

Definition at line 123 of file vpDetectorBase.h.

References m_timeout_ms.

Referenced by vpDetectorDataMatrixCode::vpDetectorDataMatrixCode().

Member Data Documentation

◆ m_face_cascade

cv::CascadeClassifier vpDetectorFace::m_face_cascade

protected

Haar cascade classifier file name.

Definition at line 105 of file vpDetectorFace.h.

Referenced by detect(), setCascadeClassifierFile(), and vpDetectorFace().

◆ m_faces

std::vector<cv::Rect> vpDetectorFace::m_faces

protected

Bounding box of each detected face.

Definition at line 104 of file vpDetectorFace.h.

Referenced by detect(), and vpDetectorFace().

◆ m_frame_gray

cv::Mat vpDetectorFace::m_frame_gray

protected

OpenCV image used as input for the face detection.

Definition at line 106 of file vpDetectorFace.h.

Referenced by detect(), and vpDetectorFace().

◆ m_message

std::vector<std::string> vpDetectorBase::m_message

protectedinherited

Message attached to each object.

Definition at line 129 of file vpDetectorBase.h.

Referenced by vpDetectorAprilTag::detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), vpDetectorFace::detect(), vpDetectorQRCode::detect(), getMessage(), getMessage(), vpDetectorBase(), and vpDetectorBase().

◆ m_nb_objects

size_t vpDetectorBase::m_nb_objects

protectedinherited

Number of detected objects.

Definition at line 130 of file vpDetectorBase.h.

Referenced by vpDetectorAprilTag::detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), vpDetectorFace::detect(), vpDetectorQRCode::detect(), getNbObjects(), vpDetectorBase(), and vpDetectorBase().

◆ m_polygon

std::vector<std::vector<vpImagePoint> > vpDetectorBase::m_polygon

protectedinherited

For each object, defines the polygon that contains the object.

Definition at line 128 of file vpDetectorBase.h.

Referenced by vpDetectorAprilTag::detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), vpDetectorFace::detect(), vpDetectorQRCode::detect(), getBBox(), getCog(), getMessage(), getPolygon(), getPolygon(), vpDetectorAprilTag::getTagsCorners(), vpDetectorBase(), and vpDetectorBase().

◆ m_timeout_ms

unsigned long vpDetectorBase::m_timeout_ms

protectedinherited

Detection timeout.

Definition at line 131 of file vpDetectorBase.h.

Referenced by vpDetectorDataMatrixCode::detect(), setTimeout(), vpDetectorBase(), and vpDetectorBase().

Public Member Functions

Protected Attributes

Inherited functionalities from vpDetectorBase

Detailed Description

Tutorials & Examples

Constructor & Destructor Documentation

◆ vpDetectorFace()

Member Function Documentation

◆ detect() [1/2]

◆ detect() [2/2]

◆ getBBox()

◆ getCog()

◆ getMessage() [1/2]

◆ getMessage() [2/2]

◆ getNbObjects()

◆ getPolygon() [1/2]

◆ getPolygon() [2/2]

◆ setCascadeClassifierFile()

◆ setTimeout()

Member Data Documentation

◆ m_face_cascade

◆ m_faces

◆ m_frame_gray

◆ m_message

◆ m_nb_objects

◆ m_polygon

◆ m_timeout_ms