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I am running solvepnPransac, I get my rvec and tvec Mats back, which are object-space coordinates. I invert them, using this: (from: http://stackoverflow.com/questions/18637494/camera-position-in-world-coordinate-from-cvsolvepnp?rq=1)

cv::Mat R;
  cv::Rodrigues(rvec, R); // R is 3x3

  R = R.t();  // rotation of inverse
  tvec = -R * tvec; // translation of inverse

  cv::Mat T(4, 4, R.type()); // T is 4x4
  T(cv::Range(0, 3), cv::Range(0, 3)) = R * 1; // copies R into T
  T(cv::Range(0, 3), cv::Range(3, 4)) = tvec * 1; // copies tvec into T
  // fill the last row of T (NOTE: depending on your types, use float or double)
  double *p = T.ptr<double>(3);
  p[0] = p[1] = p[2] = 0; p[3] = 1;


  std::cout << T << std::endl;
  // T is a 4x4 matrix with the pose of the camera in the object frame

That SHOULD give me the camera pose. But I cant really tell, as it doesn't seem to be additive. What I mean is, the values move a tiny amount as I move the camera, as if they are just showing me the motion per frame, and not adding it to the previous motion.

Is this expected? Or have i done something wrong?

I am running solvepnPransac, solvepnPransac using arbitrary points, found with FAST detector and triangulated to 3d. I get my rvec and tvec Mats back, which are object-space coordinates. When i print them though, they all stay at around zero, no matter how I invert them, using this: (from: http://stackoverflow.com/questions/18637494/camera-position-in-world-coordinate-from-cvsolvepnp?rq=1)move the camera.

cv::Mat R;
  cv::Rodrigues(rvec, R); // R is 3x3

  R = R.t();  // rotation of inverse
  tvec = -R * tvec; // translation of inverse

  cv::Mat T(4, 4, R.type()); // T is 4x4
  T(cv::Range(0, 3), cv::Range(0, 3)) = R * 1; // copies R into T
  T(cv::Range(0, 3), cv::Range(3, 4)) = tvec * 1; // copies tvec into T
  // fill 
I flip the last row of T (NOTE: depending on your types, use float or double)
  double *p = T.ptr<double>(3);
  p[0] = p[1] = p[2] = 0; p[3] = 1;


  std::cout << T << std::endl;
  // T is matrix, to get the camera-centric coordinates, and see a 4x4 matrix with similar thing. The camera pose hover between -0.01 and 0.1, no matter the pose of the camera in the object frame

I am running solvepnPransac solvePNPransac using arbitrary points, found with FAST detector and triangulated to 3d. I get my rvec and tvec Mats back, which are object-space coordinates. When i print them though, they all stay at around zero, no matter how I move the camera.

I flip the matrix, to get the camera-centric coordinates, and see a similar thing. The camera pose hover between -0.01 and 0.1, no matter the motion.

Is this possibly because the coordinates are from a random one of the sampled points, and it changes?

How could I get the actual camera world coordinates updating as I move it?

Thanks!