3D reconstruction is an important topic in computer vision. Given a set of 2D images, we can reconstruct the 3D scene using relevant algorithms. OpenCV provides algorithms that can find the relationship between various objects in those 2D images to compute their 3D positions in its calib3d module.
This module can also handle camera calibration, which is essential for estimating the parameters of the camera. These parameters define how the camera sees the scene in front of it. We need to know these parameters to design algorithms, or else we might get unexpected results.
Let's consider the following diagram:
As we can see ...