The camera speed.
Vec2D.X depicts the movement speed at ground-level, in terrain-space units per second.
Vec2D.Y defines the power by which the relative distance-to-ground is raised, before multiplying it with the speed at ground-level.
(10|0.5) will move at 10 terrain-space units per second when at ground-level, i.e. when the distance-to-ground is minimal (see MeshCameraWorld.MinimumDistance). At a distance of twice the minimum, the ground-level speed will be multiplied by
2^0.5 ~= 1.41.