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2013-09-04 18:02:22 -0500 | commented question | How is the [R|t] matrix actually found when using the EPnP algorithm? Does anybody know how I can get a hold of Alexander Shishkov? It looks like he wrote the EPnP algorithm code and is the most equipped to answer my question. Thank you! |

2013-09-04 17:55:38 -0500 | commented question | solvePnP returns wrong result Have you tried to reproject the image points to see what is happening visually? Maybe there is an angle "wrapping" somewhere. For example, if you have a vehicle that is heading approximately 0 degrees (North), you might have a few readings at 359, 0, 1 degrees. I also know that the rotation vector (rvec) is expressed as "compact" representation of Rodrigues parameters, which are not easy to visualize. You will want to use cv::Rodrigues function to convert your rvec to easier to visualize Euler angles (roll, pitch, heading). The iterative methods used for pose estimation require an initial guess. It is possible that the method will converge to an incorrect pose if given a bad initial guess. I would recommend using the EPnP algorithm which is non-iterative. |

2013-08-07 11:21:14 -0500 | received badge | ● Organizer (source) |

2013-07-29 13:18:15 -0500 | asked a question | How is the [R|t] matrix actually found when using the EPnP algorithm? I am using OpenCV's I have found this paper (http://cvlabwww.epfl.ch/~lepetit/papers/lepetit_ijcv08.pdf) to be very helpful in understanding how the four control points are found in the camera frame of reference, but the paper does I have looked through the OpenCV source code and have located the "compute_R_and_T()" function, but have struggled to understand what all is going on. Are there any technical papers or OpenCV documentation that could help me out? Thanks, Mike |

2013-07-23 12:36:37 -0500 | commented question | Is anyone using P3P or EPNP in solvePnP? Is there any documentation or references that can explain how the joint rotation-translation matrix [R|t] is computed once the position of the 3-D points are found in camera coordinates using the EPnP algorithm? I have found the EPnP paper (http://cvlabwww.epfl.ch/~lepetit/papers/lepetit_ijcv08.pdf) to be helpful in understanding how the 3-D locations are found in camera coordinates, but the paper does not explain how [R|t] is determined. Thank you to anyone who can point me in the right direction. I am working on my Master's thesis and need to understand how [R|t] is found so that I can write about it. |

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