Calculating Extremes of Camera FOV Given Heading and Angle

Question

If I have a unit vector H - a heading that represents a camera centre of view, how can I calculate corresponding vectors for H₁, H₂, H₃ and H₄ that represent the extremes of view given a given number of degrees of total width θ_w and height θ_h variation?

I do not need to account for camera 'roll' (pitch and yaw are obviously accounted for within the initial vector).

This is for the purpose of implementing a drone camera simulation.

For example for similar θ_w and θ_h of 40 degrees, I need

H₁ to be H rotated +20 deg in camera width and + 20 deg in camera height

H₂ to be H rotated +20 deg in camera width and - 20 deg in camera height

... and so on

Answer 1

Use spherical coordinates, make the translation to these and the problem is easy and goes away with simple less or than greater than comparisons.

I chose to work mainly in Cartesian coordinates, then use cart2sph().