Camera position calculation

Hey guys! I want to calculate the position of my camera in a room.
The room in my case, is a "monitor lightstage", that consists of six monitors that are arranged in a cube. In this cube, my camera is positioned.
I already calibrated my camera with opencv code, and also checked if the intrinsics and extrinsics are correct, using matlab. Now i want to calculate the cameras position in the room. For this, i used chessboards, that are displayed …

case code computervision hey monitors opencv room six