2D-plus-depth or also called 2D +'Z' format is a Stereoscopic Video Coding format that is used for 3D displays, such as Philips WOWvx. Philips discontinued work on the WOWvx line in 2009, citing "current market developments."
Next to each 2D image frame a greyscale depthmap indicates if a specific pixel in the 2D image needs to be shown in front of the display (white) or behind the screen plane (black). The 256 greyscales can build a smooth gradient of depth within the image. Processing within the monitor used this input to render the multiview images.
2D-plus-depth has the advantage that is has a limited bandwidth increase compared to 2D (compressed greyscale increases bandwidth 5-20%) so that it can be used in existing distribution infrastructures. Also 2D-plus-depth format offers flexibility and compatibility with existing production equipment and compression tools. Moreover it allows applications to use different 3D display screen sizes and designs in the same system.
2D-plus-depth is not compatible with existing 2D or 3D-Ready displays. The format has been criticized due to the limited amount of depth that can be displayed in an 8-bit grayscale.
There is no way to accurately generate a 2D+Depth Depth Map from a live stereoscopic feed.
It is also very difficult to accurately render a Depth Map from two stereoscopic Left / Right views offline without artifacting.