Due to interreflections, the marked scene point is brighter when not directly lit (inverse pattern) as compared to when directly lit. This results in a binarization error as shown on the right. Such errors can happen for low-frequency projected patterns.
Decoding for high-frequency patterns
High frequency patterns are binarized correctly in the presence of interreflections. See paper for explanation.
Logical coding and decoding: Designinng patterns with high spatial frequencies
By using simple logical operations, codes with only high spatial frequencies can be constructed from conventional codes.
Depth map comparison
Since conventional codes make errors for low frequency patterns (high significance bits), the resulting error in depth maps is large. Our logical codes produce a nearly error free depth map while requiring the same number of images as conventional codes.