# Revision history [back]

### How is the [R|t] matrix actually found when using the EPnP algorithm?

I am using OpenCV's EPnP algorithm to solve for the pose of an aircraft with a known pattern of LEDs. I have been able to get pose estimation working without too much trouble, but I am now in the writing phase of my thesis and have some questions about how the algorithm actually works. I was hoping that someone could point me towards some information that might help to put me on the right track.

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 not go on to explain how the rotation-translation matrix [R|t] is actually found, which gives us the pose information.

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

### How is the [R|t] matrix actually found when using the EPnP algorithm?

I am using OpenCV's EPnP algorithm to solve for the pose of an aircraft with a known pattern of LEDs. I have been able to get pose estimation working without too much trouble, but I am now in the writing phase of my thesis and have some questions about how the algorithm actually works. I was hoping that someone could point me towards some information that might help to put me on the right track.

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 not go on to explain how the rotation-translation matrix [R|t] is actually found, which gives us the pose information.

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