Epipolar line

An epipolar line is the image-plane trace of an epipolar plane. Given one point in the first camera image, the partner of that scene point must lie on the corresponding epipolar line in the other view. A fundamental matrix maps the first point to coefficients of that line.^[ref]

For example, let $q_L=(100,50,1{)}^{\mathsf{T}}$ andThen $F{q}_L=(0,-1,50{)}^{\mathsf{T}}$, so a candidate $q_R=(u,v,1{)}^{\mathsf{T}}$ satisfies $-v+50=0$. The partner can have different horizontal coordinate $u$, but must lie on row 50 in this ideal model. Intersecting candidate matches with this line reduces the search; it does not resolve repeated textures or guarantee that a visible partner exists.