2D-plus-depth
Encyclopedia
2D-plus-Depth or also called 2D +'Z' format (not to be confused with 2D plus Delta
or 2D-plus-DOT) 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".
Each 2D image frame is supplemented with a greyscale depth map
which 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.
Supported by various companies across the display industry, 2D-plus-Depth has been standardized in MPEG as an extension for 3D filed under ISO/IEC FDIS 23002-3:2007(E).
increase compared to 2D (compressed greyscale increases bandwidth 5–20%) so that it can be used in existing distribution infrastructures.
2D-plus-Depth offers flexibility and compatibility with existing production equipment and compression tools.
It allows applications to use different 3D display screen sizes and designs in the same system.
2d-plus-Depth cannot handle transparency (semi-transparent objects in the scene) and occlusion (an object blocking the view of another). The 2d plus DOT format takes these factors into account. Additionally, it cannot handle reflection, refraction (beyond simple transparency) and other optical phenomena.
Creation of accurate 2D-plus-Depth is generally costly and difficult, though recent advances in range imaging
have made this process more accessible.
2d-plus-Depth lacks the potential increase in resolution of using two complete images.
Depth cannot be reliably estimated for a monocular video in most cases. Notable exceptions are camera motion scenes when object motion is static or almost absent. This allows automatic depth estimation. In general case only semi-automatic approach is viable for 2D to 2D-plus-depth conversion. Philips developed a 3D content creation software suite named BlueBox which includes semi-automated conversion of 2D content into 2D-plus-Depth format and automatic generation of 2D-plus-Depth from stereo.
Stereoscopic to 2D-plus-Depth conversion involves several algorithms including scene change detection, segmentation, motion estimation and image matching. But automatic stereo to 2D+Depth conversion is possible due to new high performance software and CPU even in a live mode.
and Scalable Video Coding
), and 2D plus Delta
.
2D plus Delta
2D Plus Delta is a standards listed methodology as part of MPEG2, and MPEG4, specifically on the H.264 implementation of Multiview Video Coding extension...
or 2D-plus-DOT) is a Stereoscopic Video Coding
Stereoscopic Video Coding
-3D Video Coding:3D Video Coding is one of the stages required for the deployment of stereoscopic content in the home. There are three techniques which are used to achieve stereoscopic video:# Color shifting...
format that is used for 3D displays, such as Philips
Philips
Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....
WOWvx. Philips discontinued work on the WOWvx line in 2009, citing "current market developments".
Overview
The 2D-plus-Depth format is described in a Philips' white paper and articles.Each 2D image frame is supplemented with a greyscale depth map
Depth map
In 3D computer graphics a depth map is an image or image channel that contains information relating to the distance of the surfaces of scene objects from a viewpoint. The term is related to and may be analogous to depth buffer, Z-buffer, Z-buffering and Z-depth...
which 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.
Supported by various companies across the display industry, 2D-plus-Depth has been standardized in MPEG as an extension for 3D filed under ISO/IEC FDIS 23002-3:2007(E).
Advantages
2D-plus-Depth has the advantage that it has a limited bandwidthBandwidth (computing)
In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...
increase compared to 2D (compressed greyscale increases bandwidth 5–20%) so that it can be used in existing distribution infrastructures.
2D-plus-Depth offers flexibility and compatibility with existing production equipment and compression tools.
It allows applications to use different 3D display screen sizes and designs in the same system.
Disadvantages
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 greyscale.2d-plus-Depth cannot handle transparency (semi-transparent objects in the scene) and occlusion (an object blocking the view of another). The 2d plus DOT format takes these factors into account. Additionally, it cannot handle reflection, refraction (beyond simple transparency) and other optical phenomena.
Creation of accurate 2D-plus-Depth is generally costly and difficult, though recent advances in range imaging
Range imaging
Range imaging is the name for a collection of techniques which are used to produce a 2D image showing the distance to points in a scene from a specific point, normally associated with some type of sensor device....
have made this process more accessible.
2d-plus-Depth lacks the potential increase in resolution of using two complete images.
Depth cannot be reliably estimated for a monocular video in most cases. Notable exceptions are camera motion scenes when object motion is static or almost absent. This allows automatic depth estimation. In general case only semi-automatic approach is viable for 2D to 2D-plus-depth conversion. Philips developed a 3D content creation software suite named BlueBox which includes semi-automated conversion of 2D content into 2D-plus-Depth format and automatic generation of 2D-plus-Depth from stereo.
Stereoscopic to 2D-plus-Depth conversion involves several algorithms including scene change detection, segmentation, motion estimation and image matching. But automatic stereo to 2D+Depth conversion is possible due to new high performance software and CPU even in a live mode.
Alternatives
Other 3D formats are stereo (left-right or alternating frames) and multiview 3D format (such as Multiview Video CodingMultiview Video Coding
Multiview Video Coding is an amendment to H.264/MPEG-4 AVC video compression standard developed with joint efforts by MPEG/VCEG that enables efficient encoding of sequences captured simultaneously from multiple cameras using a single video stream....
and Scalable Video Coding
Scalable Video Coding
Scalable Video Coding is the name for the Annex G extension of the H.264/MPEG-4 AVC video compression standard. SVC standardizes the encoding of a high-quality video bitstream that also contains one or more subset bitstreams. A subset video bitstream is derived by dropping packets from the...
), and 2D plus Delta
2D plus Delta
2D Plus Delta is a standards listed methodology as part of MPEG2, and MPEG4, specifically on the H.264 implementation of Multiview Video Coding extension...
.