The filled dot is the ephemeral dot at the 3D pivot, 0,0,0 — the still point the whole gyro turns around.
The hollow dot is its shadow: the same point projected straight down onto the floor. The dashed line is the drop. Two dots, one real and one cast — and this shadow is honest geometry, a projection, not the muddled "photon-shadow" from before.
The three bright axes are a real orthonormal frame — the rotational axes of a 3-axis gyro (axle + two wheel diameters).
Their shadows are the same three axes projected onto the floor — 3D flattened to 2D, one dimension dropped. Watch the lengths: an axis tipping toward vertical casts a short shadow, one lying flat casts a long one. Shadow length reads out tilt.