General lens model

General lens model are based on mathematical descriptions of ideal projections. In the radially symmetric models below theta (θ) is the angle between view ray and optical axis.

model name	ideal projection	$r = k_{1}\theta+k_{2}\theta^3$	$r = \frac {(l+1) \sin \theta}{l+\cos \theta}$
perspective projection(pinhole camera )	$r = f \tan \theta$	$r = \theta+\frac{1}{3}\theta^3$
stereographic projection	$r = 2 f \tan(\theta/2)$	$r = \theta+\frac{1}{12}\theta^3$
equidistance projection	$r = f$
quisolid angle projection	$r = 2 f \sin(\theta/2)$
Peleng	$r = f \sin (b\theta)$
orthogonal projection	$r = f \sin (\theta)$