Visual Servoing Platform  version 3.2.0 under development (2018-08-16)
tutorial-homography-from-points.cpp
#include <visp3/vision/vpHomography.h>
#include <visp3/core/vpMeterPixelConversion.h>
int main()
{
double L = 0.1;
std::vector<vpPoint> oP;
oP.push_back(vpPoint(-L, -L, 0));
oP.push_back(vpPoint(2 * L, -L, 0));
oP.push_back(vpPoint(L, 3 * L, 0));
oP.push_back(vpPoint(-L, 4 * L, 0));
vpHomogeneousMatrix bMo(0.1, 0, 1, 0, vpMath::rad(15), 0);
vpHomogeneousMatrix aMb(0.2, -0.1, 0.1, vpMath::rad(-3), vpMath::rad(20), vpMath::rad(5));
vpHomogeneousMatrix aMo = aMb * bMo;
std::vector<vpPoint> aP(4), bP(4);
std::vector<double> xa(4), ya(4), xb(4), yb(4);
for (unsigned int i = 0; i < 4; i++) {
oP[i].project(aMo);
xa[i] = oP[i].get_x();
ya[i] = oP[i].get_y();
oP[i].project(bMo);
xb[i] = oP[i].get_x();
yb[i] = oP[i].get_y();
}
vpHomography::DLT(xb, yb, xa, ya, aHb, true);
std::cout << "Estimated homography using DLT:\n" << aHb / aHb[2][2] << std::endl;
vpHomography::HLM(xb, yb, xa, ya, true, aHb);
std::cout << "Estimated homography using HLM:\n" << aHb / aHb[2][2] << std::endl;
aHb.computeDisplacement(aRb, atb, n);
std::cout << "\nEstimated displacement:" << std::endl;
std::cout << " atb: " << atb.t() << std::endl;
atub.buildFrom(aRb);
std::cout << " athetaub: ";
for (unsigned int i = 0; i < 3; i++)
std::cout << vpMath::deg(atub[i]) << " ";
std::cout << std::endl;
std::cout << " n: " << n.t() << std::endl;
vpImagePoint iPa, iPb;
vpMeterPixelConversion::convertPoint(cam, xb[3], yb[3], iPb);
vpMeterPixelConversion::convertPoint(cam, xa[3], ya[3], iPa);
std::cout << "Ground truth: Point 3 in pixels in frame b: " << iPb << std::endl;
std::cout << "Ground truth: Point 3 in pixels in frame a: " << iPa << std::endl;
// Project the position in pixel of point 3 from the homography
std::cout << "Estimation from homography: Point 3 in pixels in frame a: " << vpHomography::project(cam, aHb, iPb)
<< std::endl;
}