
Basics of Map Projection 71
= 2 tan
Φ
2
⇒ Φ = 2 tan
−1
y
4R
(4.55)
For orthographic projection we have h = ∞
y = R sin Φ
⇒ Φ = sin
−1
y
R
(4.56)
4.6 Conical Map Projection
Figure 4.5 shows that conic map projection has a lot of similarity to the
diagram and equations for cylindrical map projection. Therefore conical map
projection can be developed with slight modification and difference. The taper
of the cone is characterised by the ratio of its cross sectional radius to the
length of the slope from its apex. This ratio is constant for any distance from
the apex of a given cone and is called constant of the cone c given by the
equation
c = sinα (4.57)
where α is the