vpDetectorFace Class Reference

#include <visp3/detection/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
}

A more complete example that works with images acquired from a camera is provided in tutorial-face-detector-live.cpp.

Examples

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

Definition at line 90 of file vpDetectorFace.h.

Constructor & Destructor Documentation

vpDetectorFace()

BEGIN_VISP_NAMESPACE vpDetectorFace::vpDetectorFace

(

)

Default constructor.

Definition at line 50 of file vpDetectorFace.cpp.

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 101 of file vpDetectorFace.cpp.

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

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 82 of file vpDetectorFace.cpp.

References vpImageConvert::convert(), and m_frame_gray.

getBBox()

vpRect vpDetectorBase::getBBox ( size_t  i ) const

inherited

Return the bounding box of the ith object.

Examples

tutorial-apriltag-detector-live-T265-realsense.cpp, tutorial-apriltag-detector.cpp, 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 93 of file vpDetectorBase.cpp.

References vpDetectorBase::m_polygon.

getCog()

vpImagePoint vpDetectorBase::getCog ( size_t  i ) const

inherited

Return the center of gravity location of the ith object.

Examples

mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, servoBiclopsPoint2DArtVelocity.cpp, servoPololuPtuPoint2DJointVelocity.cpp, and tutorial-flir-ptu-ibvs.cpp.

Definition at line 79 of file vpDetectorBase.cpp.

References vpDetectorBase::m_polygon.

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, tutorial-apriltag-detector.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.

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 65 of file vpDetectorBase.cpp.

References vpException::badValue, vpDetectorBase::m_message, and vpDetectorBase::m_polygon.

getNbObjects()

size_t vpDetectorBase::getNbObjects ( ) const

inlineinherited

Return the number of objects that are detected.

Examples

catchAprilTag.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, mbot-apriltag-pbvs.cpp, tutorial-apriltag-detector-live-T265-realsense.cpp, tutorial-apriltag-detector-live-rgbd-realsense.cpp, tutorial-apriltag-detector-live-rgbd-structure-core.cpp, tutorial-apriltag-detector-live.cpp, tutorial-apriltag-detector.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, and tutorial-mb-generic-tracker-apriltag-webcam.cpp.

Definition at line 108 of file vpDetectorBase.h.

getPolygon() [1/2]

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

inlineinherited

Returns object container box as a vector of points.

Examples

catchAprilTag.cpp, mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.cpp, tutorial-apriltag-detector-live-rgbd-realsense.cpp, tutorial-apriltag-detector-live-rgbd-structure-core.cpp, tutorial-apriltag-detector.cpp, tutorial-barcode-detector-live.cpp, and tutorial-barcode-detector.cpp.

Definition at line 113 of file vpDetectorBase.h.

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 51 of file vpDetectorBase.cpp.

References vpException::badValue, and vpDetectorBase::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 58 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.

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 94 of file vpDetectorFace.h.

Referenced by detect(), and setCascadeClassifierFile().

m_faces

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

protected

Bounding box of each detected face.

Definition at line 93 of file vpDetectorFace.h.

Referenced by detect().

m_frame_gray

cv::Mat vpDetectorFace::m_frame_gray

protected

OpenCV image used as input for the face detection.

Definition at line 95 of file vpDetectorFace.h.

Referenced by detect().

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 detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), and vpDetectorBase::getMessage().

m_nb_objects

size_t vpDetectorBase::m_nb_objects

protectedinherited

Number of detected objects.

Definition at line 130 of file vpDetectorBase.h.

Referenced by detect(), vpDetectorAprilTag::detect(), and vpDetectorDataMatrixCode::detect().

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 detect(), vpDetectorAprilTag::detect(), vpDetectorDataMatrixCode::detect(), vpDetectorBase::getBBox(), vpDetectorBase::getCog(), vpDetectorBase::getMessage(), vpDetectorBase::getPolygon(), and vpDetectorAprilTag::getTagsCorners().

m_timeout_ms

unsigned long vpDetectorBase::m_timeout_ms

protectedinherited

Detection timeout.

Definition at line 131 of file vpDetectorBase.h.

Referenced by vpDetectorDataMatrixCode::detect().