  This paper proposes an observer for generating depth maps of a scene from a
sequence of measurements acquired by a two-plane light-field (plenoptic)
camera. The observer is based on a gradient-descent methodology. The use of
motion allows for estimation of depth maps where the scene contains
insufficient texture for static estimation methods to work. A rigourous
analysis of stability of the observer error is provided, and the observer is
tested in simulation, demonstrating convergence behaviour.
