I compute the distance from an object (Chessboard) using OpenCV and my camera parameters following those steps:
1- findChessboardCorners
2- solvePnP
3- ->Distance from the translation vector given by solvePnP
The issue is that the error is increasing linearly when I get far from the camera.
The error is simply the difference between the real distance and the one given by my program.
The camera is calibrated (focal length 2.8mm, wide angle + distortion)
I want to know why the error is increasing? Is that normal?