Let AB be sea level, projection distance x, COS∠FCH=φ, and find the relationship between X and φ.

The height of point f is h 1, and the height of point e is h2, CF=a, CA=b, and de = c.

It is known that h 1, h2, a, b and c are fixed values.

Because C D=AB, CA=DB, the quadrilateral ABDC is a parallelogram, the height of C D is constant, ∠CAB=θ.

The height of c is acosφ+h 1, and the height of d is bsinθ.

(bsinθ-h2)？ +(x-bcosθ)？ =c？ ( 1)

acosφ + h 1 = bsinθ (2)

(1), (2) The equations are parametric equations of x and φ about θ.

I really don't know what the result will be.