  In this paper, we propose a hybrid depth imaging system in which a
polarisation camera is augmented by a second image from a standard digital
camera. For this modest increase in equipment complexity over conventional
shape-from-polarisation, we obtain a number of benefits that enable us to
overcome longstanding problems with the polarisation shape cue. The stereo cue
provides a depth map which, although coarse, is metrically accurate. This is
used as a guide surface for disambiguation of the polarisation surface normal
estimates using a higher order graphical model. In turn, these are used to
estimate diffuse albedo. By extending a previous shape-from-polarisation method
to the perspective case, we show how to compute dense, detailed maps of
absolute depth, while retaining a linear formulation. We show that our hybrid
method is able to recover dense 3D geometry that is superior to
state-of-the-art shape-from-polarisation or two view stereo alone.
