Visual Servoing Platform  version 3.6.1 under development (2024-04-20)
mbtEdgeKltTracking.cpp

Example of Hybrid Tracking of MBT and MBT KTL on an image sequence containing a cube.

/****************************************************************************
*
* ViSP, open source Visual Servoing Platform software.
* Copyright (C) 2005 - 2023 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 https://visp.inria.fr 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 visp@inria.fr
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* Description:
* Example of Hybrid Tracking of MBT and MBT KTL.
*
*****************************************************************************/
#include <iostream>
#include <visp3/core/vpConfig.h>
#if defined(VISP_HAVE_MODULE_MBT) && defined(VISP_HAVE_MODULE_KLT) && defined(VISP_HAVE_OPENCV) && \
defined(VISP_HAVE_DISPLAY) && defined(HAVE_OPENCV_IMGPROC) && defined(HAVE_OPENCV_VIDEO)
#include <visp3/core/vpDebug.h>
#include <visp3/core/vpHomogeneousMatrix.h>
#include <visp3/core/vpIoTools.h>
#include <visp3/core/vpMath.h>
#include <visp3/gui/vpDisplayD3D.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/io/vpParseArgv.h>
#include <visp3/io/vpVideoReader.h>
#include <visp3/mbt/vpMbEdgeKltTracker.h>
#define GETOPTARGS "x:m:i:n:de:chtfColwvp"
void usage(const char *name, const char *badparam)
{
#if VISP_HAVE_DATASET_VERSION >= 0x030600
std::string ext("png");
#else
std::string ext("pgm");
#endif
fprintf(stdout, "\n\
Example of tracking based on the 3D model.\n\
\n\
SYNOPSIS\n\
%s [-i <test image path>] [-x <config file>]\n\
[-m <model name>] [-n <initialisation file base name>] [-e <last frame index>]\n\
[-t] [-c] [-d] [-h] [-f] [-C] [-o] [-w] [-l] [-v] [-p]\n",
name);
fprintf(stdout, "\n\
OPTIONS: \n\
-i <input image path> \n\
Set image input path.\n\
From this path read images \n\
\"mbt/cube/image%%04d.%s\". These \n\
images come from visp-images-x.y.z.tar.gz available \n\
on the ViSP website.\n\
Setting the VISP_INPUT_IMAGE_PATH environment\n\
variable produces the same behaviour than using\n\
this option.\n\
\n\
-x <config file> \n\
Set the config file (the xml file) to use.\n\
The config file is used to specify the parameters of the tracker.\n\
\n\
-m <model name> \n\
Specify the name of the file of the model\n\
The model can either be a vrml model (.wrl) or a .cao file.\n\
\n\
-e <last frame index> \n\
Specify the index of the last frame. Once reached, the tracking is stopped\n\
\n\
-f \n\
Do not use the vrml model, use the .cao one. These two models are \n\
equivalent and comes from ViSP-images-x.y.z.tar.gz available on the ViSP\n\
website. However, the .cao model allows to use the 3d model based tracker \n\
without Coin.\n\
\n\
-C \n\
Track only the cube (not the cylinder). In this case the models files are\n\
cube.cao or cube.wrl instead of cube_and_cylinder.cao and \n\
cube_and_cylinder.wrl.\n\
\n\
-n <initialisation file base name> \n\
Base name of the initialisation file. The file will be 'base_name'.init .\n\
This base name is also used for the Optional picture specifying where to \n\
click (a .ppm picture).\n\
\n\
-t \n\
Turn off the display of the the moving edges and Klt points. \n\
\n\
-d \n\
Turn off the display.\n\
\n\
-c\n\
Disable the mouse click. Useful to automate the \n\
execution of this program without human intervention.\n\
\n\
-o\n\
Use Ogre3D for visibility tests\n\
\n\
-w\n\
When Ogre3D is enable [-o] show Ogre3D configuration dialog thatallows to set the renderer.\n\
\n\
-l\n\
Use the scanline for visibility tests.\n\
\n\
-v\n\
Compute covariance matrix.\n\
\n\
-p\n\
Compute gradient projection error.\n\
\n\
-h \n\
Print the help.\n\n",
ext.c_str());
if (badparam)
fprintf(stdout, "\nERROR: Bad parameter [%s]\n", badparam);
}
bool getOptions(int argc, const char **argv, std::string &ipath, std::string &configFile, std::string &modelFile,
std::string &initFile, long &lastFrame, bool &displayFeatures, bool &click_allowed, bool &display,
bool &cao3DModel, bool &trackCylinder, bool &useOgre, bool &showOgreConfigDialog, bool &useScanline,
bool &computeCovariance, bool &projectionError)
{
const char *optarg_;
int c;
while ((c = vpParseArgv::parse(argc, argv, GETOPTARGS, &optarg_)) > 1) {
switch (c) {
case 'e':
lastFrame = atol(optarg_);
break;
case 'i':
ipath = optarg_;
break;
case 'x':
configFile = optarg_;
break;
case 'm':
modelFile = optarg_;
break;
case 'n':
initFile = optarg_;
break;
case 't':
displayFeatures = false;
break;
case 'f':
cao3DModel = true;
break;
case 'c':
click_allowed = false;
break;
case 'd':
display = false;
break;
case 'C':
trackCylinder = false;
break;
case 'o':
useOgre = true;
break;
case 'l':
useScanline = true;
break;
case 'w':
showOgreConfigDialog = true;
break;
case 'v':
computeCovariance = true;
break;
case 'p':
projectionError = true;
break;
case 'h':
usage(argv[0], nullptr);
return false;
break;
default:
usage(argv[0], optarg_);
return false;
break;
}
}
if ((c == 1) || (c == -1)) {
// standalone param or error
usage(argv[0], nullptr);
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)
{
try {
std::string env_ipath;
std::string opt_ipath;
std::string ipath;
std::string opt_configFile;
std::string configFile;
std::string opt_modelFile;
std::string modelFile;
std::string opt_initFile;
std::string initFile;
long opt_lastFrame = -1;
bool displayFeatures = true;
bool opt_click_allowed = true;
bool opt_display = true;
bool cao3DModel = false;
bool trackCylinder = true;
bool useOgre = false;
bool showOgreConfigDialog = false;
bool useScanline = false;
bool computeCovariance = false;
bool projectionError = false;
bool quit = false;
#if VISP_HAVE_DATASET_VERSION >= 0x030600
std::string ext("png");
#else
std::string ext("pgm");
#endif
// 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_configFile, opt_modelFile, opt_initFile, opt_lastFrame, displayFeatures,
opt_click_allowed, opt_display, cao3DModel, trackCylinder, useOgre, showOgreConfigDialog,
useScanline, computeCovariance, projectionError)) {
return EXIT_FAILURE;
}
// Test if an input path is set
if (opt_ipath.empty() && env_ipath.empty()) {
usage(argv[0], nullptr);
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
<< std::endl;
return EXIT_FAILURE;
}
// Get the option values
if (!opt_ipath.empty())
ipath = vpIoTools::createFilePath(opt_ipath, "mbt/cube/image%04d." + ext);
else
ipath = vpIoTools::createFilePath(env_ipath, "mbt/cube/image%04d." + ext);
if (!opt_configFile.empty())
configFile = opt_configFile;
else if (!opt_ipath.empty())
configFile = vpIoTools::createFilePath(opt_ipath, "mbt/cube.xml");
else
configFile = vpIoTools::createFilePath(env_ipath, "mbt/cube.xml");
if (!opt_modelFile.empty()) {
modelFile = opt_modelFile;
}
else {
std::string modelFileCao;
std::string modelFileWrl;
if (trackCylinder) {
modelFileCao = "mbt/cube_and_cylinder.cao";
modelFileWrl = "mbt/cube_and_cylinder.wrl";
}
else {
modelFileCao = "mbt/cube.cao";
modelFileWrl = "mbt/cube.wrl";
}
if (!opt_ipath.empty()) {
if (cao3DModel) {
modelFile = vpIoTools::createFilePath(opt_ipath, modelFileCao);
}
else {
#ifdef VISP_HAVE_COIN3D
modelFile = vpIoTools::createFilePath(opt_ipath, modelFileWrl);
#else
std::cerr << "Coin is not detected in ViSP. Use the .cao model instead." << std::endl;
modelFile = vpIoTools::createFilePath(opt_ipath, modelFileCao);
#endif
}
}
else {
if (cao3DModel) {
modelFile = vpIoTools::createFilePath(env_ipath, modelFileCao);
}
else {
#ifdef VISP_HAVE_COIN3D
modelFile = vpIoTools::createFilePath(env_ipath, modelFileWrl);
#else
std::cerr << "Coin is not detected in ViSP. Use the .cao model instead." << std::endl;
modelFile = vpIoTools::createFilePath(env_ipath, modelFileCao);
#endif
}
}
}
if (!opt_initFile.empty())
initFile = opt_initFile;
else if (!opt_ipath.empty())
initFile = vpIoTools::createFilePath(opt_ipath, "mbt/cube");
else
initFile = vpIoTools::createFilePath(env_ipath, "mbt/cube");
vpVideoReader reader;
reader.setFileName(ipath);
try {
reader.open(I);
}
catch (...) {
std::cout << "Cannot open sequence: " << ipath << std::endl;
return EXIT_FAILURE;
}
if (opt_lastFrame > 1 && opt_lastFrame < reader.getLastFrameIndex())
reader.setLastFrameIndex(opt_lastFrame);
reader.acquire(I);
// initialise a display
#if defined(VISP_HAVE_X11)
#elif defined(VISP_HAVE_GDI)
#elif defined(HAVE_OPENCV_HIGHGUI)
#elif defined(VISP_HAVE_D3D9)
#elif defined(VISP_HAVE_GTK)
#else
opt_display = false;
#endif
if (opt_display) {
#if defined(VISP_HAVE_DISPLAY)
display.init(I, 100, 100, "Test tracking");
#endif
}
// Initialise the tracker: camera parameters, moving edge and KLT settings
#if defined(VISP_HAVE_PUGIXML)
// From the xml file
tracker.loadConfigFile(configFile);
#else
// Corresponding parameters manually set to have an example code
// By setting the parameters:
cam.initPersProjWithoutDistortion(547, 542, 338, 234);
vpMe me;
me.setMaskSize(5);
me.setMaskNumber(180);
me.setRange(7);
me.setThreshold(15);
me.setMu1(0.5);
me.setMu2(0.5);
klt.setMaxFeatures(10000);
klt.setWindowSize(5);
klt.setQuality(0.01);
klt.setBlockSize(3);
tracker.setCameraParameters(cam);
tracker.setMovingEdge(me);
tracker.setKltOpencv(klt);
tracker.setKltMaskBorder(5);
// Specify the clipping to
tracker.setNearClippingDistance(0.01);
tracker.setFarClippingDistance(0.90);
// tracker.setClipping(tracker.getClipping() | vpMbtPolygon::LEFT_CLIPPING |
// vpMbtPolygon::RIGHT_CLIPPING | vpMbtPolygon::UP_CLIPPING |
// vpMbtPolygon::DOWN_CLIPPING); // Equivalent to FOV_CLIPPING
#endif
// Display the moving edges, and the Klt points
tracker.setDisplayFeatures(displayFeatures);
// Tells if the tracker has to use Ogre3D for visibility tests
tracker.setOgreVisibilityTest(useOgre);
if (useOgre)
tracker.setOgreShowConfigDialog(showOgreConfigDialog);
// Tells if the tracker has to use the scanline visibility tests
tracker.setScanLineVisibilityTest(useScanline);
// Tells if the tracker has to compute the covariance matrix
tracker.setCovarianceComputation(computeCovariance);
// Tells if the tracker has to compute the projection error
tracker.setProjectionErrorComputation(projectionError);
// Retrieve the camera parameters from the tracker
tracker.getCameraParameters(cam);
// Loop to position the cube
if (opt_display && opt_click_allowed) {
while (!vpDisplay::getClick(I, false)) {
vpDisplay::displayText(I, 15, 10, "click after positioning the object", vpColor::red);
}
}
// Load the 3D model (either a vrml file or a .cao file)
tracker.loadModel(modelFile);
// Initialise the tracker by clicking on the image
// This function looks for
// - a ./cube/cube.init file that defines the 3d coordinates (in meter,
// in the object basis) of the points used for the initialisation
// - a ./cube/cube.ppm file to display where the user have to click
// (Optional, set by the third parameter)
if (opt_display && opt_click_allowed) {
tracker.initClick(I, initFile, true);
tracker.getPose(cMo);
// display the 3D model at the given pose
tracker.display(I, cMo, cam, vpColor::red);
}
else {
vpHomogeneousMatrix cMoi(0.02044769891, 0.1101505452, 0.5078963719, 2.063603907, 1.110231561, -0.4392789872);
tracker.initFromPose(I, cMoi);
}
// track the model
tracker.track(I);
tracker.getPose(cMo);
if (opt_display)
while (!reader.end()) {
// acquire a new image
reader.acquire(I);
// display the image
if (opt_display)
// Test to reset the tracker
if (reader.getFrameIndex() == reader.getFirstFrameIndex() + 10) {
vpTRACE("Test reset tracker");
if (opt_display)
tracker.resetTracker();
#if defined(VISP_HAVE_PUGIXML)
tracker.loadConfigFile(configFile);
#else
// Corresponding parameters manually set to have an example code
// By setting the parameters:
cam.initPersProjWithoutDistortion(547, 542, 338, 234);
vpMe me;
me.setMaskSize(5);
me.setMaskNumber(180);
me.setRange(7);
me.setThreshold(15);
me.setMu1(0.5);
me.setMu2(0.5);
klt.setMaxFeatures(10000);
klt.setWindowSize(5);
klt.setQuality(0.01);
klt.setBlockSize(3);
tracker.setCameraParameters(cam);
tracker.setMovingEdge(me);
tracker.setKltOpencv(klt);
tracker.setKltMaskBorder(5);
// Specify the clipping to
tracker.setNearClippingDistance(0.01);
tracker.setFarClippingDistance(0.90);
// tracker.setClipping(tracker.getClipping() | vpMbtPolygon::LEFT_CLIPPING |
// vpMbtPolygon::RIGHT_CLIPPING | vpMbtPolygon::UP_CLIPPING |
// vpMbtPolygon::DOWN_CLIPPING); // Equivalent to FOV_CLIPPING
#endif
tracker.loadModel(modelFile);
tracker.setCameraParameters(cam);
tracker.setOgreVisibilityTest(useOgre);
tracker.setScanLineVisibilityTest(useScanline);
tracker.setCovarianceComputation(computeCovariance);
tracker.setProjectionErrorComputation(projectionError);
tracker.initFromPose(I, cMo);
}
// Test to set an initial pose
if (reader.getFrameIndex() == reader.getFirstFrameIndex() + 50) {
cMo.buildFrom(0.0439540832, 0.0845870108, 0.5477322481, 2.179498458, 0.8611798108, -0.3491961946);
vpTRACE("Test set pose");
tracker.setPose(I, cMo);
// if (opt_display) {
// // display the 3D model
// tracker.display(I, cMo, cam, vpColor::darkRed);
// // display the frame
// vpDisplay::displayFrame (I, cMo, cam, 0.05);
// }
}
// track the object: stop tracking from frame 40 to 50
if (reader.getFrameIndex() - reader.getFirstFrameIndex() < 40 ||
reader.getFrameIndex() - reader.getFirstFrameIndex() >= 50) {
tracker.track(I);
tracker.getPose(cMo);
if (opt_display) {
// display the 3D model
tracker.display(I, cMo, cam, vpColor::darkRed);
// display the frame
vpDisplay::displayFrame(I, cMo, cam, 0.05);
}
}
if (opt_click_allowed) {
vpDisplay::displayText(I, 10, 10, "Click to quit", vpColor::red);
if (vpDisplay::getClick(I, false)) {
quit = true;
break;
}
}
if (computeCovariance) {
std::cout << "Covariance matrix: \n" << tracker.getCovarianceMatrix() << std::endl << std::endl;
}
if (projectionError) {
std::cout << "Projection error: " << tracker.getProjectionError() << std::endl << std::endl;
}
if (opt_display)
}
std::cout << "Reached last frame: " << reader.getFrameIndex() << std::endl;
if (opt_click_allowed && !quit) {
}
reader.close();
return EXIT_SUCCESS;
}
catch (const vpException &e) {
std::cout << "Catch an exception: " << e << std::endl;
return EXIT_FAILURE;
}
}
#else
int main()
{
std::cout << "visp_mbt, visp_gui modules and OpenCV are required to run "
"this example."
<< std::endl;
return EXIT_SUCCESS;
}
#endif
Generic class defining intrinsic camera parameters.
void initPersProjWithoutDistortion(double px, double py, double u0, double v0)
static const vpColor red
Definition: vpColor.h:211
static const vpColor darkRed
Definition: vpColor.h:212
Display for windows using Direct3D 3rd party. Thus to enable this class Direct3D should be installed....
Definition: vpDisplayD3D.h:101
Display for windows using GDI (available on any windows 32 platform).
Definition: vpDisplayGDI.h:128
The vpDisplayGTK allows to display image using the GTK 3rd party library. Thus to enable this class G...
Definition: vpDisplayGTK.h:128
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:128
static bool getClick(const vpImage< unsigned char > &I, bool blocking=true)
static void display(const vpImage< unsigned char > &I)
static void displayFrame(const vpImage< unsigned char > &I, const vpHomogeneousMatrix &cMo, const vpCameraParameters &cam, double size, const vpColor &color=vpColor::none, unsigned int thickness=1, const vpImagePoint &offset=vpImagePoint(0, 0), const std::string &frameName="", const vpColor &textColor=vpColor::black, const vpImagePoint &textOffset=vpImagePoint(15, 15))
static void flush(const vpImage< unsigned char > &I)
static void displayText(const vpImage< unsigned char > &I, const vpImagePoint &ip, const std::string &s, const vpColor &color)
error that can be emitted by ViSP classes.
Definition: vpException.h:59
Implementation of an homogeneous matrix and operations on such kind of matrices.
void buildFrom(const vpTranslationVector &t, const vpRotationMatrix &R)
static std::string getViSPImagesDataPath()
Definition: vpIoTools.cpp:1832
static std::string createFilePath(const std::string &parent, const std::string &child)
Definition: vpIoTools.cpp:2195
Wrapper for the KLT (Kanade-Lucas-Tomasi) feature tracker implemented in OpenCV. Thus to enable this ...
Definition: vpKltOpencv.h:73
void setBlockSize(int blockSize)
Definition: vpKltOpencv.h:266
void setQuality(double qualityLevel)
Definition: vpKltOpencv.h:355
void setHarrisFreeParameter(double harris_k)
Definition: vpKltOpencv.h:274
void setMaxFeatures(int maxCount)
Definition: vpKltOpencv.h:314
void setMinDistance(double minDistance)
Definition: vpKltOpencv.h:323
void setWindowSize(int winSize)
Definition: vpKltOpencv.h:376
void setPyramidLevels(int pyrMaxLevel)
Definition: vpKltOpencv.h:342
static double rad(double deg)
Definition: vpMath.h:127
Hybrid tracker based on moving-edges and keypoints tracked using KLT tracker.
virtual void loadConfigFile(const std::string &configFile, bool verbose=true) vp_override
virtual void track(const vpImage< unsigned char > &I) vp_override
virtual void setOgreVisibilityTest(const bool &v) vp_override
virtual void setProjectionErrorComputation(const bool &flag) vp_override
virtual void setScanLineVisibilityTest(const bool &v) vp_override
virtual void display(const vpImage< unsigned char > &I, const vpHomogeneousMatrix &cMo, const vpCameraParameters &cam, const vpColor &col, unsigned int thickness=1, bool displayFullModel=false) vp_override
void resetTracker() vp_override
virtual void setNearClippingDistance(const double &dist) vp_override
virtual void setFarClippingDistance(const double &dist) vp_override
virtual void setPose(const vpImage< unsigned char > &I, const vpHomogeneousMatrix &cdMo) vp_override
virtual void setClipping(const unsigned int &flags) vp_override
virtual void setCameraParameters(const vpCameraParameters &cam) vp_override
void setMovingEdge(const vpMe &me)
virtual void setKltOpencv(const vpKltOpencv &t)
void setKltMaskBorder(const unsigned int &e)
virtual void setOgreShowConfigDialog(bool showConfigDialog)
Definition: vpMbTracker.h:650
virtual void getCameraParameters(vpCameraParameters &cam) const
Definition: vpMbTracker.h:248
virtual void setDisplayFeatures(bool displayF)
Definition: vpMbTracker.h:518
virtual void getPose(vpHomogeneousMatrix &cMo) const
Definition: vpMbTracker.h:414
virtual void setAngleDisappear(const double &a)
Definition: vpMbTracker.h:481
virtual void setCovarianceComputation(const bool &flag)
Definition: vpMbTracker.h:500
virtual void initClick(const vpImage< unsigned char > &I, const std::string &initFile, bool displayHelp=false, const vpHomogeneousMatrix &T=vpHomogeneousMatrix())
virtual vpMatrix getCovarianceMatrix() const
Definition: vpMbTracker.h:265
virtual double getProjectionError() const
Definition: vpMbTracker.h:310
virtual void initFromPose(const vpImage< unsigned char > &I, const std::string &initFile)
virtual void loadModel(const std::string &modelFile, bool verbose=false, const vpHomogeneousMatrix &T=vpHomogeneousMatrix())
virtual void setAngleAppear(const double &a)
Definition: vpMbTracker.h:470
virtual unsigned int getClipping() const
Definition: vpMbTracker.h:256
Definition: vpMe.h:124
void setMu1(const double &mu_1)
Definition: vpMe.h:399
void setRange(const unsigned int &range)
Definition: vpMe.h:429
void setLikelihoodThresholdType(const vpLikelihoodThresholdType likelihood_threshold_type)
Definition: vpMe.h:519
void setMaskNumber(const unsigned int &mask_number)
Definition: vpMe.cpp:488
void setThreshold(const double &threshold)
Definition: vpMe.h:480
void setSampleStep(const double &sample_step)
Definition: vpMe.h:436
void setMaskSize(const unsigned int &mask_size)
Definition: vpMe.cpp:496
void setMu2(const double &mu_2)
Definition: vpMe.h:406
@ NORMALIZED_THRESHOLD
Definition: vpMe.h:135
static bool parse(int *argcPtr, const char **argv, vpArgvInfo *argTable, int flags)
Definition: vpParseArgv.cpp:69
Class that enables to manipulate easily a video file or a sequence of images. As it inherits from the...
void acquire(vpImage< vpRGBa > &I)
void setLastFrameIndex(const long last_frame)
long getLastFrameIndex()
void open(vpImage< vpRGBa > &I)
void setFileName(const std::string &filename)
long getFirstFrameIndex()
long getFrameIndex() const
#define vpTRACE
Definition: vpDebug.h:405
void display(vpImage< unsigned char > &I, const std::string &title)
Display a gray-scale image.
VISP_EXPORT int wait(double t0, double t)