Post in the water
Figure 1 shows side- and front-view of a post standing in the water. v presents the side-view of the Picture Plane (PP). Note that the part of the post above the water AM and its reflection-image BM are of equal height. The lines from SP through A, M, B (side-view) define p,n,q in the front-view.
Note : g presents the mirror image of f , MR-AR is the reflection angle of f. (MR-AR = MR-BR)
Figure 2 : A photographic presentation similar to above, note that in reality the two "posts" are of equal size.