How can I print a variable in the ComputeError() in the terminal？

[yangliu9527]

I want to print some values calculated in the computeError() function of an edge during the optimization process, but it seems that the output stream like std::cout/std::cerr doesn't work in the computeError(). I have tried the write(ostream &os) function but it is used for save information in a file. I want to see some information in real-time because there is a unknown bug which will cause the system crashing. Do you know the solution? Thank you.

[RainerKuemmerle]

Do you have a minimal working example that illustrates the problem?
Using cout/cerr should work as expected. In the g2o_viewer cerr is redirected to the GUI and you should see the output there instead of on the console.

About the crash:
Does gdb provide insights? Or tools like valgrind?

[yangliu9527]

I have solved the crash bug but the printing problem still exists. Here is an example of working computeError() function, where both the
cout << error << endl;
cout << "x="<<proj_x<<", y="<<proj_y<<endl; don't work. Do you have any solution? Thank you.

void EdgeLaneAlignOnlyPose::computeError()
{
const g2o::VertexSE3Expmap *v1 = static_cast<const g2o::VertexSE3Expmap *>(_vertices[0]);
Eigen::Vector2d proj_p = pCamera->project(v1->estimate().map(Pw));
double proj_x = proj_p[0];
double proj_y = proj_p[1];
cout << "x="<<proj_x<<", y="<<proj_y<<endl;
if (proj_x <= 1 || proj_x >= (pImEdgeDT->cols - 1) || proj_y <= 1 || proj_y >= (pImEdgeDT->rows - 1))
{
setLevel(1);
_error.setZero();
return;
}
else
{
// double error = static_cast(pImEdgeDT->ptr(proj_y)[proj_x]);
double error = static_cast(Utility::GetPixelValue(pImEdgeDT, proj_x, proj_y));
cout << error <<endl;
_error(0, 0) = error;
}
}

[RainerKuemmerle]

Try to use a debugger along with a breakpoint in the respective functions. Without a minimal working example, I cannot tell what is going on.