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Multi-View Video Coding

mpeg scene image information

Definition: Multi-view image display systems provide the viewer with the appropriate monoscopic or stereoscopic view of a scene.

Recent advances in multi-view three dimensional (3-D) television may revolutionalize information systems in the near future. Three or more cameras may be used to form a multi-ocular system for the production of several image sequences obtained from slightly different viewpoints. Multi-view image display systems may provide the viewer with the appropriate monoscopic or stereoscopic view of a scene, depending on his position. As an example, an autostereoscopic display system is implemented using several projectors and a lenticular screen.

Another example is integral imaging, which is a technique that is capable of creating and encoding a true volume spatial optical model of the object scene in the form of a planar intensity distribution by using unique optical components (arrays of lenses).

However, the cost for the associated recording and transmission systems increases considerably as the number of views increases. In order to reduce this cost, virtual images from intermediate viewpoints have to be generated, using the existing real views and additional disparity information. Virtual view generation can be either image-based, i.e. no explicit 3-D modeling of the scene is made, however disparity estimation may be used to improve the quality of the generated intermediate images or 3-D model based, where the true shapes and texture of the objects in the scene are determined and computer graphics techniques are used to render other viewpoints of the 3-D scene.

Efficient communication of multi-view image sequences can be achieved by transmitting the encoded image sequences obtained from the real views along with disparity or depth information. Intermediate views are then produced at the receiver using spatial interpolation on the basis of intensity images and transmitted disparity or depth information. By transmitting additional bit rate corresponding to disparity or depth information, the generation of intermediate images is simplifi the complexity of the receiver is significantly reduced. Offsetting this is the cost of transmitting this additional bit rate, which may be considerable.

While MPEG-2 and MPEG-4 provide some support for the coding of standard stereo and multi-view scenes, these techniques have specific limitations and cannot support new applications with significant user interaction. Therefore, MPEG recently started a new activity, namely MPEG 3DAV, with the aim of exploring new applications, such as omni- directional video, interactive stereo and multi-view video and even free viewpoint video, where a user can freely navigate within a 3-D environment captured using a small number of real cameras. Although many of these applications can be realized through the application of existing MPEG tools, especially those for the coding of audio and visual objects contained under MPEG-4, the need for further extensions to existing standards is now being explored.

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