We present blue-c, a new immersive projection and 3D video acquisition environment for virtual design and collaboration. It combines simultaneous acquisition of multiple live video streams with advanced 3D projection technology in a CAVE^TM-like environment, creating the impression of total immersion. The blue-c portal currently consists of three rectangular projection screens that are built from glass panels containing liquid crystal layers. These screens can be switched from a whitish opaque state (for projection) to a transparent state (for acquisition), which allows the video cameras to "look through" the walls. Our projection technology is based on active stereo using two LCD projectors per screen. The projectors are synchronously shuttered along with the screens, the stereo glasses, active illumination devices, and the acquisition hardware. From multiple video streams, we compute a 3D video representation of the user in real time. The resulting video inlays are integrated into a networked virtual environment. Our design is highly scalable, enabling blue-c to connect to portals with less sophisticated hardware.

In this paper we present a scalable 3D video framework for capturing and rendering dynamic scenes. The acquisition system is based on multiple sparsely placed 3D video bricks, each comprising a projector, two grayscale cameras and a color camera. Relying on structured light with complementary patterns, texture images and patternaugmented views of the scene are acquired simultaneously by time multiplexed projections and synchronized camera exposures. Using space-time stereo on the acquired pattern images, high-quality depth maps are extracted, whose corresponding surface samples are merged into a viewindependent, point-based 3D data structure. This representation allows for effective photo consistency enforcement and outlier removal, leading to a significant decrease of visual artifacts and a high resulting rendering quality using EWA volume splatting. Our framework and its view-independent representation allow for simple and straightforward editing of 3D video. In order to demonstrate its flexibility, we show compositing techniques and spatio-temporal effects.

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In this paper, we present a coding framework addressing image-space compression for free-viewpoint video. Our framework is based on time-varying 3D point samples which represent real-world objects. The 3D point samples are obtained after a geometrical reconstruction from multiple pre-recorded video sequences and thus allow for arbitrary viewpoints during playback. The encoding of the data is performed as an off-line process and is not time-critical. The decoding however, must support for real-time rendering of the dynamic 3D data. We introduce a compression framework which encodes multiple point attributes like depth and color into progressive streams. The reference data structure is aligned on the original camera input images and thus enables for easy view-dependent decoding. A novel differential coding approach permits random access in constant time throughout the entire data set and thus enables arbitrary viewpoint trajectories in both time and space.

Abstract — We present a complete system for efficient 3D video object extraction, representation, coding, and interactive rendering. 3D video objects provide the same functionalities as virtual computer graphic objects but also depict motion and appearance of real world moving objects. They can be viewed interactively from any direction and can be integrated in complete 3D scenes together with other virtual or real world elements. In this work, data representation is based on 3D mesh models and view-dependent texture mapping using video textures. The geometry extraction is based on a shape-from-silhouette algorithm. The resulting voxel models are converted into 3D meshes. For efficient compression of such dynamic 3D meshes, we present a novel algorithm that significantly outperforms available standard approaches. The corresponding video textures are preprocessed taking the object’s shape into account and coded using H.264/AVC. The presented results show that a complete and efficient transmission system for 3D video objects can be built. I.

In this paper, we discuss data transmission in telepresence environments for collaborative virtual reality applications. We analyze data streams in the context of networked virtual environments and classify them according to their traffic characteristics. Special emphasis is put on geometry-enhanced (3D) video. We review architectures for real-time 3D video pipelines and derive theoretical bounds on the minimal system latency as a function of the transmission and processing delays. Furthermore, we discuss bandwidth issues of differential update coding for 3D video. In our telepresence system – the blue-c – we use a point-based 3D video technology which allows for differentially encoded 3D representations of human users. While we discuss the considerations which lead to the design of our three-stage 3D video pipeline, we also elucidate some critical implementation details regarding decoupling of acquisition, processing and rendering frame rates and audio/video synchronization. Finally, we demonstrate the communication and networking features of the blue-c system in its full deployment. We show how the system can possibly be controlled to face processing or networking bottlenecks by adapting the multiple system components like audio, application data and 3D video. Keywords: H.4.3 [Communications Applications]: Computer conferencing, teleconferencing, and videoconferencing.

An overview of 3D and free viewpoint video is given in this paper with special focus on related standardization activities in MPEG. Free viewpoint video allows the user to freely navigate within real world visual scenes, as known from virtual worlds in computer graphics. Suitable 3D scene representation formats are classified and the processing chain is explained. Examples are shown for image-based and model-based free viewpoint video systems, highlighting standards conform realization using MPEG-4. Then the principles of 3D video are introduced providing the user with a 3D depth impression of the observed scene. Example systems are described again focusing on their realization based on MPEG-4. Finally multi-view video coding is described as a key component for 3D and free viewpoint video systems. MPEG is currently working on a new standard for multi-view video coding. The conclusion is that the necessary technology including standard media formats for 3D and free viewpoint is available or will be available in the near future, and that there is a clear demand from industry and user side for such applications. 3DTV at home and free viewpoint video on DVD will be available soon, and will create huge new markets.

Abstract. Image-based full body 3D reconstruction for tele-immersive applications generates large amount of data points, which have to be sent through the network in real-time. In this paper we introduce a skeleton-based compression method using motion estimation where kinematic parameters of the human body are extracted from the point cloud data in each frame. First we address the issues regarding the data capturing and transfer to a remote site for the tele-immersive collaboration. We compare the results of the existing compression methods and the proposed skeleton-based compression technique. We examine robustness and efficiency of the algorithm through experimental results with our multi-camera tele-immersion system. The proposed skeleton-based method provides high and flexible compression ratios (from 50:1 to 5000:1) with reasonable reconstruction quality (peak signal-to-noise ratio from 28 to 31 dB). 1

Abstract — ViPiD is a complete framework for audio and 3D video capturing of one or several moving persons as well as the creation of 3D person models for intuitive dialog systems. Therefore we are setting up a multi-camera environment for 3D scene analysis, incorporating aspects such as 3D/4D reconstruction, motion estimation, virtual camera integration, coding of time variant 3D meshes and free viewpoint video. I.

IN:SHOP uses the blue-c 3D video technology to implement distributed shopping in a shared virtual world. IN:SHOP combines traditional shopping and marketing structures with 3D computer graphics, telepresence, spatially immersive displays, and internet shopping paradigms to create a flexible and adaptable commercial environment. The application is an enhancement of the traditional, physical shopping and the shop itself. It redefines the experience and architecture of commercial spaces. We implemented the concept for a haute couture fashion shop and a car seller using two interconnected virtual reality theaters. In this paper, we present the concept of IN:SHOP and the implementation inside the blue-c environment.