Visual Servoing Platform  version 3.5.1 under development (2023-05-30)
vpDetectorDataMatrixCode Class Reference

#include <visp3/detection/vpDetectorDataMatrixCode.h>

+ Inheritance diagram for vpDetectorDataMatrixCode:

Public Member Functions

 vpDetectorDataMatrixCode ()
virtual ~vpDetectorDataMatrixCode ()
bool detect (const vpImage< unsigned char > &I)
Inherited functionalities from vpDetectorBase
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)

Protected Attributes

std::vector< std::vector< vpImagePoint > > m_polygon
std::vector< std::string > m_message
size_t m_nb_objects
unsigned long m_timeout_ms

Detailed Description

Base class for bar code detector. This class is a wrapper over libdmtx available from Installation instructions are provided here

The detect() function allows to detect multiple QR codes in an image. Once detected, for each QR code it is possible to retrieve the location of the corners using getPolygon(), the encoded message using getMessage(), the bounding box using getBBox() and the center of gravity using getCog().

The following sample code shows how to use this class to detect QR codes in an image.

#include <visp3/detection/vpDetectorDataMatrixCode.h>
#include <visp3/io/vpImageIo.h>
int main()
vpImageIo::read(I, "bar-code.pgm");
bool status = detector.detect(I);
if (status) {
for(size_t i=0; i < detector.getNbObjects(); i++) {
std::cout << "Bar code " << i << ":" << std::endl;
std::vector<vpImagePoint> p = detector.getPolygon(i);
for(size_t j=0; j < p.size(); j++)
std::cout << " Point " << j << ": " << p[j] << std::endl;
std::cout << " Message: \"" << detector.getMessage(i) << "\"" << std::endl;
std::vector< std::vector< vpImagePoint > > & getPolygon()
size_t getNbObjects() const
std::vector< std::string > & getMessage()
bool detect(const vpImage< unsigned char > &I)
static void read(vpImage< unsigned char > &I, const std::string &filename, int backend=IO_DEFAULT_BACKEND)
Definition: vpImageIo.cpp:148

The previous example may produce results like:

Bar code 0:
Point 0: 273.21, 78.9799
Point 1: 390.016, 85.1014
Point 2: 388.024, 199.185
Point 3: 269.23, 192.96
Message: "datamatrix 1"
Bar code 1:
Point 0: 262.23, 396.404
Point 1: 381.041, 402.631
Point 2: 378.92, 524.188
Point 3: 257.916, 519.962
Message: "datamatrix 2"

Other examples are also provided in tutorial-barcode-detector.cpp and tutorial-barcode-detector-live.cpp

tutorial-barcode-detector-live.cpp, and tutorial-barcode-detector.cpp.

Definition at line 113 of file vpDetectorDataMatrixCode.h.

Constructor & Destructor Documentation

◆ vpDetectorDataMatrixCode()

vpDetectorDataMatrixCode::vpDetectorDataMatrixCode ( )

Default constructor that does nothing except setting detection timeout to 50ms. This value could be changed using setTimeout().

Definition at line 53 of file vpDetectorDataMatrixCode.cpp.

References vpDetectorBase::setTimeout().

◆ ~vpDetectorDataMatrixCode()

virtual vpDetectorDataMatrixCode::~vpDetectorDataMatrixCode ( )

Definition at line 117 of file vpDetectorDataMatrixCode.h.

Member Function Documentation

◆ detect()

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

Detect datamatrix codes in the image. Return true if a code is detected, false otherwise. There is the setTimeout() function that allows to tune the value of the timeout used to detect a datamatrix code. By default, there is a timeout of 50 ms set in the constructor.

I: Input image.

Implements vpDetectorBase.

Definition at line 62 of file vpDetectorDataMatrixCode.cpp.

References vpImage< Type >::bitmap, vpImage< Type >::getHeight(), vpImage< Type >::getWidth(), vpDetectorBase::m_message, vpDetectorBase::m_nb_objects, vpDetectorBase::m_polygon, and vpDetectorBase::m_timeout_ms.

◆ getBBox()

vpRect vpDetectorBase::getBBox ( size_t  i) const

◆ getCog()

vpImagePoint vpDetectorBase::getCog ( size_t  i) const

Return the center of gravity location of the ith object.

mbot-apriltag-2D-half-vs.cpp, mbot-apriltag-ibvs.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 ( )

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

testAprilTag.cpp, tutorial-apriltag-detector.cpp, tutorial-barcode-detector-live.cpp, and tutorial-barcode-detector.cpp.

Definition at line 106 of file vpDetectorBase.h.

◆ getMessage() [2/2]

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

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

Definition at line 67 of file vpDetectorBase.cpp.

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

◆ getNbObjects()

◆ getPolygon() [1/2]

◆ getPolygon() [2/2]

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

Returns ith object container box as a vector of points.

Definition at line 55 of file vpDetectorBase.cpp.

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

◆ setTimeout()

void vpDetectorBase::setTimeout ( unsigned long  timeout_ms)

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

Definition at line 129 of file vpDetectorBase.h.

Referenced by vpDetectorDataMatrixCode().

Member Data Documentation

◆ m_message

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

Message attached to each object.

Definition at line 68 of file vpDetectorBase.h.

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

◆ m_nb_objects

size_t vpDetectorBase::m_nb_objects

Number of detected objects.

Definition at line 69 of file vpDetectorBase.h.

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

◆ m_polygon

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

◆ m_timeout_ms

unsigned long vpDetectorBase::m_timeout_ms

Detection timeout.

Definition at line 70 of file vpDetectorBase.h.

Referenced by detect().