# Pinhole camera, angular FOV from sensor and focal length
sensorWidth = 6.4 mm in 3..15
focalLength = 4 mm in 2..20
fieldOfView := 2 * atan(sensorWidth/(2*focalLength)) [rad]
check field of view: fieldOfView >= 0.5 rad
scenario telephoto: focalLength = 12 mm

# Scene coverage at a chosen distance, for an ideal rectilinear pinhole camera.
distance = 1000 mm in 100..5000
sceneWidth := distance * sensorWidth / focalLength [mm]
halfWidthAt(x: mm) := x * tan(fieldOfView/2) [mm]