Methods and apparatus for enhancing depth maps with polarization cues

Apparatus comprising

• (a) one or more cameras configured
• (i) to capture a first set of images of an object, which first set of images comprises one or more images, and
• (ii) to capture a second set of images of the object, which second set includes a first polarized image, a second polarized image and a third polarized image, such that the first, second and third polarized images capture light that has been filtered at a first polarizer angle, a second polarizer angle and a third polarizer angle, respectively, the first, second and third polarizer angles being different from each other;
• and
• (b) one or more computers that are programmed
• (i) to calculate, based on the first set of images, a first depth map of a surface of the object,
• (ii) to calculate, based on the second set of images, polarization surface normals of the surface, and
• (iii) to perform a computation that (A) is based on the first depth map and the polarization surface normals, (B) disregards gradients in a first region of the surface that has a lower degree of polarization than the rest of the surface, and (C) calculates a second depth map of the surface, which second depth map is more accurate than the first depth map in part because the gradients in the first region of the surface are disregarded.