The present invention relates to determining a virtual viewpoint television.
Television is likely the most important visual information system in past decades, and it has indeed become a commodity of modern human life. With a conventional TV, the viewer's viewpoint for a particular video is determined and fixed by that of the acquisition camera. Recently, a new technology has emerged, free viewpoint television (FTV), which promises to bring a revolution to TV viewing. The premise of FTV is to provide the viewer the freedom of choosing his/her own viewpoint for watching the video by providing multiple video streams captured by a set of cameras. In addition to home entertainment, the FTV concept can also be used in other related domains such as gaming and education. The user-chosen viewpoint(s) does not need to coincide with those of the acquisition cameras. Accordingly, the FTV is not merely a simple view change by switching cameras (as possible with some DVD for a couple of preset views). The FTV technology requires a whole spectrum of technologies ranging from acquisition hardware, coding technology, bandwidth management techniques, standardization for interoperability, etc. One of the particular technologies to implement FTV is virtual view synthesis.
The essence of virtual view synthesis includes given a set of images (or video) acquired from different viewpoints to construct a new image that appears to be acquired from a different viewpoint. This multiple image modification is also sometimes referred to as image-based rendering (IBR).
In the FTV application, it is unlikely that the camera calibration information is likely to be available (e.g., imagine shooting a movie with multiple cameras which need to be calibrated each time they are moved). This renders IBR methods requiring full camera calibration generally inapplicable in most cases. Moreover, before virtual view synthesis, the virtual view should to be specified. Existing IBR techniques use a variety of way to achieve this. For example, the virtual view specification may be straightforward when the entire setup is fully calibrated. For example, the virtual view specification may be based on the user's manual picking of some points including the projection of the virtual camera center. None of these approaches is readily applicable to the FTV application with uncalibrated cameras, where an ordinary user needs an intuitive way of specifying some desired (virtual) viewpoints.
What is desirable is a framework for the rendering problem in FTV based on IBR. The approach preferably includes multiple images from uncalibrated cameras as the input. Further, while a virtual view is synthesized mainly from two principal views chosen by a viewer, other views may also be employed to improve the quality. Starting with two optimal (user-chosen) views also contributes to the reduction in the number of required views. In addition a technique for specifying the virtual view in uncalibrated cameras is desirable, and thus providing a practical solution to view specification in the FTV application without requiring either full camera calibration or complicated user interaction, both of which are all impractical for FTV.
The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings.