OpenCV to OpenGL coordinate system transform

Question

I have two right handed coordinate systems.

OpenCV

As you can see with the black arrows, the camera looks down the positive $Z$ axis. You can ignore the rest of the diagram.

OpenGL

Although not visible here, the camera in OpenGL looks down the -Z axis. I want to transform a 3D point in front of the camera in the OpenCV coordinate system to a 3D point in front of the camera in the OpenGL.

I'm trying to represent this in a 4x4 matrix that concatenates R and T with 0001 at the bottom.

So far, I've tried this

1  0  0  0
0 -1  0  0
0  0  -1 0
0  0  0  1

but it doesn't seem to do anything, nothing shows up in the OpenGL coordinate system.

Answer 1

The camera coordinates of OpenCV goes X right, Y down, Z forward. While the camera coordinates of OpenGL goes X right, Y up, Z inward.

Use solvePnP as one of the most commonly used example. You get a 3x3 rotation matrix R and a 1x3 translation vector T, and create a 4x4 view matrix M with R and T. Simply inverse the 2nd and 3rd row of M and you will get a view matrix for OpenGL rendering.