Epipolar Geometry is the geometry of 2 camera views of the same 3D scnee.
If one camera sees a point somewhere in it’s image, the matching point in the second image is not anywhere in that second, it lies on a line and that line is called epipolar line
Camera 1 center, Camera 2 center, and world point define 1 plane known as the epipolar plane
Constraint
If x is a point in image 1 and x’ is its matching point in image 2, then they satisfy:
and are image points in homogeneous coordinates - F is the Fundamental Matrix
this equation gives you the epipolar line