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

Tracking of a line using vpMe.

* ViSP, open source Visual Servoing Platform software.
* Copyright (C) 2005 - 2019 by Inria. All rights reserved.
* This software is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
* See the file LICENSE.txt at the root directory of this source
* distribution for additional information about the GNU GPL.
* For using ViSP with software that can not be combined with the GNU
* GPL, please contact Inria about acquiring a ViSP Professional
* Edition License.
* See for more information.
* This software was developed at:
* Inria Rennes - Bretagne Atlantique
* Campus Universitaire de Beaulieu
* 35042 Rennes Cedex
* France
* If you have questions regarding the use of this file, please contact
* Inria at
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* Description:
* Tracking of a line.
* Authors:
* Eric Marchand
* Fabien Spindler
#include <visp3/core/vpConfig.h>
#include <visp3/core/vpDebug.h>
#include <iomanip>
#include <sstream>
#include <stdio.h>
#include <stdlib.h>
#if defined(VISP_HAVE_MODULE_ME) && \
(defined(VISP_HAVE_X11) || defined(VISP_HAVE_GTK) || defined(VISP_HAVE_GDI) || defined(VISP_HAVE_OPENCV))
#include <visp3/core/vpColor.h>
#include <visp3/core/vpImage.h>
#include <visp3/core/vpImagePoint.h>
#include <visp3/gui/vpDisplayGDI.h>
#include <visp3/gui/vpDisplayGTK.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/io/vpImageIo.h>
#include <visp3/me/vpMeLine.h>
#include <visp3/visual_features/vpFeatureBuilder.h>
#include <visp3/visual_features/vpFeatureLine.h>
#include <visp3/core/vpIoTools.h>
#include <visp3/io/vpParseArgv.h>
// List of allowed command line options
#define GETOPTARGS "cdf:hi:l:p:s:"
void usage(const char *name, const char *badparam, std::string ipath, std::string ppath, unsigned first,
unsigned last, unsigned step)
std::string ext("png");
std::string ext("pgm");
fprintf(stdout, "\n\
Tracking of a line.\n\
%s [-i <input image path>] [-p <personal image path>]\n\
[-f <first image>] [-l <last image>] [-s <step>]\n\
[-c] [-d] [-h]\n", name);
fprintf(stdout, "\n\
OPTIONS: Default\n\
-i <input image path> %s\n\
Set image input path.\n\
From this path read \"line/image.%%04d.%s\"\n\
images. \n\
Setting the VISP_INPUT_IMAGE_PATH environment\n\
variable produces the same behaviour than using\n\
this option.\n\
-p <personal image path> %s\n\
Specify a personal sequence containing images \n\
to process.\n\
By image sequence, we mean one file per image.\n\
Example : \"C:/Temp/visp-images/line/image.%%04d.%s\"\n\
%%04d is for the image numbering.\n\
-f <first image> %u\n\
First image number of the sequence.\n\
-l <last image> %u\n\
Last image number of the sequence.\n\
-s <step> %u\n\
Step between two images.\n\
Disable the mouse click. Useful to automaze the \n\
execution of this program without humain intervention.\n\
-d \n\
Turn off the display.\n\
Print the help.\n",
ipath.c_str(), ext.c_str(), ppath.c_str(), ext.c_str(), first, last, step);
if (badparam)
fprintf(stdout, "\nERROR: Bad parameter [%s]\n", badparam);
bool getOptions(int argc, const char **argv, std::string &ipath, std::string &ppath, unsigned &first, unsigned &last,
unsigned &step, bool &click_allowed, bool &display)
const char *optarg_;
int c;
while ((c = vpParseArgv::parse(argc, argv, GETOPTARGS, &optarg_)) > 1) {
switch (c) {
case 'c':
click_allowed = false;
case 'd':
display = false;
case 'i':
ipath = optarg_;
case 'p':
ppath = optarg_;
case 'f':
first = (unsigned)atoi(optarg_);
case 'l':
last = (unsigned)atoi(optarg_);
case 's':
step = (unsigned)atoi(optarg_);
case 'h':
usage(argv[0], NULL, ipath, ppath, first, last, step);
return false;
usage(argv[0], optarg_, ipath, ppath, first, last, step);
return false;
if ((c == 1) || (c == -1)) {
// standalone param or error
usage(argv[0], NULL, ipath, ppath, first, last, step);
std::cerr << "ERROR: " << std::endl;
std::cerr << " Bad argument " << optarg_ << std::endl << std::endl;
return false;
return true;
int main(int argc, const char **argv)
#if defined(VISP_HAVE_LAPACK) || defined(VISP_HAVE_EIGEN3) || defined(VISP_HAVE_OPENCV)
try {
std::string env_ipath;
std::string opt_ipath;
std::string ipath;
std::string opt_ppath;
std::string dirname;
std::string filename;
unsigned int opt_first = 1;
unsigned int opt_last = 30;
unsigned int opt_step = 1;
bool opt_click_allowed = true;
bool opt_display = true;
std::string ext("png");
std::string ext("pgm");
// Get the visp-images-data package path or VISP_INPUT_IMAGE_PATH
// environment variable value
// Set the default input path
if (!env_ipath.empty())
ipath = env_ipath;
// Read the command line options
if (getOptions(argc, argv, opt_ipath, opt_ppath, opt_first, opt_last, opt_step, opt_click_allowed,
opt_display) == false) {
// Get the option values
if (!opt_ipath.empty())
ipath = opt_ipath;
// Compare ipath and env_ipath. If they differ, we take into account
// the input path comming from the command line option
if (!opt_ipath.empty() && !env_ipath.empty() && opt_ppath.empty()) {
if (ipath != env_ipath) {
std::cout << std::endl << "WARNING: " << std::endl;
std::cout << " Since -i <visp image path=" << ipath << "> "
<< " is different from VISP_IMAGE_PATH=" << env_ipath << std::endl
<< " we skip the environment variable." << std::endl;
// Test if an input path is set
if (opt_ipath.empty() && env_ipath.empty() && opt_ppath.empty()) {
usage(argv[0], NULL, ipath, opt_ppath, opt_first, opt_last, opt_step);
std::cerr << std::endl << "ERROR:" << std::endl;
std::cerr << " Use -i <visp image path> option or set VISP_INPUT_IMAGE_PATH " << std::endl
<< " environment variable to specify the location of the " << std::endl
<< " image path where test images are located." << std::endl
<< " Use -p <personal image path> option if you want to " << std::endl
<< " use personal images." << std::endl
<< std::endl;
// Declare an image, this is a gray level image (unsigned char)
// it size is not defined yet, it will be defined when the image will
// read on the disk
unsigned iter = opt_first;
std::ostringstream s;
char cfilename[FILENAME_MAX];
if (opt_ppath.empty()) {
// Warning :
// The image sequence is not provided with the ViSP package
// therefore the program will return an error :
// !! couldn't read file visp-images/mire-2/image.0001.png
// ViSP dataset is available on the visp www site
// Set the path location of the image sequence
dirname = vpIoTools::createFilePath(ipath, "line");
// Build the name of the image file
s.setf(std::ios::right, std::ios::adjustfield);
s << "image." << std::setw(4) << std::setfill('0') << iter << "." << ext;
filename = vpIoTools::createFilePath(dirname, s.str());
else {
snprintf(cfilename, FILENAME_MAX, opt_ppath.c_str(), iter);
filename = cfilename;
// Read the image named "filename", and put the bitmap into the image structure I.
// I is initialized to the correct size
// vpImageIo::read() may throw various exception if, for example,
// the file does not exist, or if the memory cannot be allocated
try {
vpCTRACE << "Load: " << filename << std::endl;
vpImageIo::read(I, filename);
} catch (...) {
// If an exception is thrown by vpImageIo::read() it will result in the end of the program.
std::cerr << std::endl << "ERROR:" << std::endl;
std::cerr << " Cannot read " << filename << std::endl;
if (opt_ppath.empty()) {
std::cerr << " Check your -i " << ipath << " option " << std::endl
<< " or VISP_INPUT_IMAGE_PATH environment variable." << std::endl;
else {
std::cerr << " Check your -p " << opt_ppath << " option " << std::endl;
// We open a window using either X11, GTK or GDI.
#if defined VISP_HAVE_X11
vpDisplayX display;
#elif defined VISP_HAVE_GTK
vpDisplayGTK display;
#elif defined VISP_HAVE_GDI
vpDisplayGDI display;
#elif defined VISP_HAVE_OPENCV
vpDisplayOpenCV display;
if (opt_display) {
// Display size is automatically defined by the image (I) size
display.init(I, 100, 100, "Display...");
// Display the image
// The image class has a member that specify a pointer toward
// the display that has been initialized in the display declaration
// therefore is is no longer necessary to make a reference to the
// display variable.
vpMe me;
if (opt_display && opt_click_allowed)
else {
vpImagePoint ip1, ip2;
L1.initTracking(I, ip1, ip2);
if (opt_display)
if (opt_display && opt_click_allowed) {
std::cout << "A click to continue..." << std::endl;
std::cout << "----------------------------------------------------------" << std::endl;
while (iter < opt_last) {
std::cout << "----------------------------------------------------------" << std::endl;
// set the new image name
s << "image." << std::setw(4) << std::setfill('0') << iter << "." << ext;
filename = vpIoTools::createFilePath(dirname, s.str());
// read the image
vpImageIo::read(I, filename);
if (opt_display) {
// Display the image
std::cout << "Tracking on image: " << filename << std::endl;
vpTRACE("L1 : %f %f", L1.getRho(), vpMath::deg(L1.getTheta()));
vpTRACE("L1 : %f %f", l.getRho(), vpMath::deg(l.getTheta()));
if (opt_display) {
if (opt_click_allowed) {
std::cout << "A click to continue..." << std::endl;
iter += opt_step;
if (opt_display && opt_click_allowed) {
std::cout << "A click to exit..." << std::endl;
} catch (const vpException &e) {
std::cout << "Catch an exception: " << e << std::endl;
std::cout << "Cannot run this example: install Lapack, Eigen3 or OpenCV" << std::endl;
#include <iostream>
int main()
std::cout << "visp_me module or X11, GTK, GDI or OpenCV display "
"functionalities are required..."
<< std::endl;
Generic class defining intrinsic camera parameters.
static const vpColor green
Definition: vpColor.h:220
Display for windows using GDI (available on any windows 32 platform).
Definition: vpDisplayGDI.h:129
The vpDisplayGTK allows to display image using the GTK 3rd party library. Thus to enable this class G...
Definition: vpDisplayGTK.h:135
The vpDisplayOpenCV allows to display image using the OpenCV library. Thus to enable this class OpenC...
Use the X11 console to display images on unix-like OS. Thus to enable this class X11 should be instal...
Definition: vpDisplayX.h:135
static bool getClick(const vpImage< unsigned char > &I, bool blocking=true)
static void display(const vpImage< unsigned char > &I)
static void flush(const vpImage< unsigned char > &I)
error that can be emited by ViSP classes.
Definition: vpException.h:72
static void create(vpFeaturePoint &s, const vpCameraParameters &cam, const vpDot &d)
Class that defines a 2D line visual feature which is composed by two parameters that are and ,...
double getTheta() const
double getRho() const
static void read(vpImage< unsigned char > &I, const std::string &filename, int backend=IO_DEFAULT_BACKEND)
Definition: vpImageIo.cpp:148
Class that defines a 2D point in an image. This class is useful for image processing and stores only ...
Definition: vpImagePoint.h:89
void set_j(double jj)
Definition: vpImagePoint.h:309
void set_i(double ii)
Definition: vpImagePoint.h:298
static std::string getViSPImagesDataPath()
Definition: vpIoTools.cpp:1399
static std::string createFilePath(const std::string &parent, const std::string &child)
Definition: vpIoTools.cpp:1764
static double deg(double rad)
Definition: vpMath.h:106
Class that tracks in an image a line moving edges.
Definition: vpMeLine.h:149
void track(const vpImage< unsigned char > &Im)
Definition: vpMeLine.cpp:745
double getRho() const
Definition: vpMeLine.cpp:954
void display(const vpImage< unsigned char > &I, const vpColor &color, unsigned int thickness=1)
Definition: vpMeLine.cpp:223
double getTheta() const
Definition: vpMeLine.cpp:959
void initTracking(const vpImage< unsigned char > &I)
Definition: vpMeLine.cpp:235
Definition: vpMeSite.h:69
void setDisplay(vpMeSite::vpMeSiteDisplayType select)
Definition: vpMeTracker.h:148
void setMe(vpMe *p_me)
Definition: vpMeTracker.h:169
Definition: vpMe.h:119
void setRange(const unsigned int &r)
Definition: vpMe.h:330
void setPointsToTrack(const int &n)
Definition: vpMe.h:323
void setThreshold(const double &t)
Definition: vpMe.h:364
static bool parse(int *argcPtr, const char **argv, vpArgvInfo *argTable, int flags)
Definition: vpParseArgv.cpp:69
#define vpCTRACE
Definition: vpDebug.h:338
#define vpTRACE
Definition: vpDebug.h:416