pseudo expansion of field-of-view for immersive projection
TRANSCRIPT
Pseudo Expansion of Field-of-View for Immersive Projection Displays (sap 0048)
Kenji Honda∗
Tokyo Institute of TechnologyNaoki Hashimoto†
Tokyo Institute of TechnologyMakoto Sato‡
Tokyo Institute of Technology
1 Introduction
We developed a pseudo expansion of field-of-view of image con-tents for immersive projection displays like a CAVE or tiled-display. Despite the wide spread of the large and immersive dis-plays, lack of their applications is a serious problem. Our approachcan reconstruct invisible peripheral images from past image framesby using an adaptive depth model. This approach can achieve bothreal-time processing and reduction of perceptible distortion and dis-continuity in the expanded images. It also contributes to using ouraccessible image contents, like interactive video games, for the im-mersive displays, and enhancing enjoyment of them.
2 Proposed technique
Recent research to increase the view-angle of the images has beenproposed in the fields of computer graphics and computer vision.WireGL and Chromium can increase the view-angle of only the3D applications using OpenGL. Video-mosaicing techniques [Satoet al. 2006] reconstruct 3D scenes of various image contents byusing a factorization method. However, the technique requireslots of estimation processes for obtaining precise 3D models forreconstructing peripheral images from past image frames. Someapproaches with roughly-approximated 3D models [CHIBA et al.1998] are also proposed to avoid the time-consuming estimations.Although they can achieve real-time processing for various images,the rough approximation leads to uncomfortable distortions when auser’s viewpoint moves around the 3D scenes.
Therefore, in our approach, we introduce a simple depth modelbased on primitive shapes such as a rectangular solid or cylinder.When the depth model is inadequate to approximate the depth ofactual scenes, distortions will occur within the extracted images.If the model roughly approximates the scene, those distortions de-crease and have almost no effects on viewers because they occurin peripheral view. However, we can perceive distinct boundariesbetween the central part with present image frame and the periph-eral part extracted from past image frames. They have strong effectsbecause the obvious discontinuities cause sudden change of optical-flows in the peripheral view, which is well-suited to perceive suchstimuli. In order to reduce the discontinuities, we adapt the depthmodel to well-observed areas. In our approach, we change the sizeof the simple depth model according to the optical-flow obtainedonly from the focused objects on the boundary between central andperipheral region.
Invisible area surrounding the present frame is generally included inpast image frames when a viewpoint moves forward. So, by usingthe adaptive depth model, peripheral images are properly extractedfrom the past images in real-time. Of course, the distortion anddiscontinuity of the generated peripheral images are not entirely re-solved, because the simple depth model is merely approximatingthe real scene, not precisely representing it. Practically, the periph-eral regions are not so effective for precise recognition because ofthe user’s perceptual characteristics. So this approach can achieveenough approximating quality for reducing the uncomfortable feel-ings with the distortions and discontinuities. And also, it enables us
∗e-mail:[email protected]†e-mail:[email protected]‡e-mail:[email protected]
to achieve real-time processing with reduced target for calculatingoptical-flow.
We call this approach a pseudo expansion of field-of-view.
3 Implementation and results
We implemented the proposed technique on our multi-projector dis-play “D-vision” composed of a 4mx6m curved screen, 24 PCs and24 projectors. By using this implementation, we could much enjoya Sony PlayStation2 driving game with expanded field-of-view asa real-scale (Figure 1). The central 60 degrees of the field-of-viewwas covered with the present image frame, and the peripheral re-gions, up to 120 degrees, were filled with the images extracted froma past image frame, generated at 30fps with Pentium-D 3.2GHz andGeForce7800GTX.
We also performed some evaluations to show the effects for immer-sion and enjoyment of the contents. For objective evaluations, weused a visually induced perception of self-motion, called vection.Questionnaires were also used for subjective evaluations. Threeconditions used for the evaluations are 1) evenly expanded to fillthe screen, 2) expanded with video-mosaicing for real-time, 3) ex-panded with our proposed technique. From these results, we couldfind significant effects of our proposed technique for enhancingamusing factors of the contents.
Figure 1: Expanded driving games on our multi-projector display.The basic shape of the depth model is a rectangular solid. Thatis adapted based on a driving-road and road-side objects as oftenobserved targets.
References
CHIBA, N., KANO, H., HIGASHIHARA, M., AND OSUMI,M. 1998. Feature-based image mosaicing. in. Proc. IAPR Work-shop on Machine Vision Applications.
SATO, T., IKETANI, A., IKEDA, S., KANBARA, M., NAKAJIMA,N., AND YOKOYA, N. 2006. Video mosaicing for curveddocuments by structure from motion. Proc. SIGGRAPH2006Sketches.