The compression issues of panoramic video

The paper proposes efficient data compression techniques for panoramic video. Panoramic videos have been used as a means for representing dynamic scenes or paths along a static environment. They allow the user to change viewpoints interactively at a point in time or space. High-resolution panoramic videos, while desirable, consume a significant amount of storage and bandwidth for transmission, and make real-time decoding very computationally intensive. A high performance MPEG-like compression algorithm, which takes into account the random access requirements and the redundancies of the panoramic video, is presented. The transmission aspects of panoramic video over cable network, LAN and Internet are also briefly discussed.published_or_final_versio

The application of nonlinear filter banks to efficient rendering and progressive transmission of light fields

This paper studies the application of perfect reconstruction nonlinear filter banks (NFB) to the efficient rendering and progressive transmission of light fields. The reference pictures in the conventional disparity-compensated prediction encoder is decomposed using the NFB to reduce the amount of main memory needed to support fast rendering. The NFB has very low arithmetic complexity for reconstruction and small filter support which considerably simplifies the random access operations. It can also be applied to the predicted light field images to support progressive transmission. Different prediction and reconstruction strategies are also investigated to achieve different tradeoffs between memory requirement and decoding speed.published_or_final_versio

Measuring Drug Abuse: The Development of the Chinese Drug Involvement Scale in Hong Kong

The development of the Chinese Drug Involvement Scale for use in Chinese communities.Method: A battery of scales, including the Chinese Drug Involvement Scale and threemental health measures, were administered to 152 students of 13 to 18 years of age. Reliabilityand validity analyses were performed. The refined version was then cross-validated on a groupof identified drug abusers (N = 77). Results: The final version of the Chinese Drug InvolvementScale is a 22-item scale. Validation results demonstrate that the Chinese Drug Involvement Scalehas high reliability and a satisfactory level of validity. Conclusion: The Chinese Drug InvolvementScale is a global assessment of an individual's beliefs and values relating to drug use, apartfrom actual drug abuse behavior. The scale will be particularly useful for periodic assessmentsor outcome evaluation in treatment programs.postprin

Image-based rendering and synthesis

Multiview imaging (MVI) is currently the focus of some research as it has a wide range of applications and opens up research in other topics and applications, including virtual view synthesis for three-dimensional (3D) television (3DTV) and entertainment. However, a large amount of storage is needed by multiview systems and are difficult to construct. The concept behind allowing 3D scenes and objects to be visualized in a realistic way without full 3D model reconstruction is image-based rendering (IBR). Using images as the primary substrate, IBR has many potential applications including for video games, virtual travel and others. The technique creates new views of scenes which are reconstructed from a collection of densely sampled images or videos. The IBR concept has different classification such as knowing 3D models and the lighting conditions and be rendered using conventional graphic techniques. Another is lightfield or lumigraph rendering which depends on dense sampling with no or very little geometry for rendering without recovering the exact 3D-models.published_or_final_versio

Data compression and transmission aspects of panoramic videos

Panoramic videos are effective means for representing static or dynamic scenes along predefined paths. They allow users to change their viewpoints interactively at points in time or space defined by the paths. High-resolution panoramic videos, while desirable, consume a significant amount of storage and bandwidth for transmission. They also make real-time decoding computationally very intensive. This paper proposes efficient data compression and transmission techniques for panoramic videos. A high-performance MPEG-2-like compression algorithm, which takes into account the random access requirements and the redundancies of panoramic videos, is proposed. The transmission aspects of panoramic videos over cable networks, local area networks (LANs), and the Internet are also discussed. In particular, an efficient advanced delivery sharing scheme (ADSS) for reducing repeated transmission and retrieval of frequently requested video segments is introduced. This protocol was verified by constructing an experimental VOD system consisting of a video server and eight Pentium 4 computers. Using the synthetic panoramic video Village at a rate of 197 kb/s and 7 f/s, nearly two-thirds of the memory access and transmission bandwidth of the video server were saved under normal network traffic.published_or_final_versio

A virtual reality system using the concentric mosaic: Construction, rendering, and data compression

This paper proposes a new image-based rendering (IBR) technique called "concentric mosaic" for virtual reality applications. IBR using the plenoptic function is an efficient technique for rendering new views of a scene from a collection of sample images previously captured. It provides much better image quality and lower computational requirement for rendering than conventional three-dimensional (3-D) model-building approaches. The concentric mosaic is a 3-D plenoptic function with viewpoints constrained on a plane. Compared with other more sophisticated four-dimensional plenoptic functions such as the light field and the lumigraph, the file size of a concentric mosaic is much smaller. In contrast to a panorama, the concentric mosaic allows users to move freely in a circular region and observe significant parallax and lighting changes without recovering the geometric and photometric scene models. The rendering of concentric mosaics is very efficient, and involves the reordering and interpolating of previously captured slit images in the concentric mosaic. It typically consists of hundreds of high-resolution images which consume a significant amount of storage and bandwidth for transmission. An MPEG-like compression algorithm is therefore proposed in this paper taking into account the access patterns and redundancy of the mosaic images. The compression algorithms of two equivalent representations of the concentric mosaic, namely the multiperspective panoramas and the normal setup sequence, are investigated. A multiresolution representation of concentric mosaics using a nonlinear filter bank is also proposed.published_or_final_versio

The social in social work practice - Shamans and social workers

Byneglecting the religious dimension, social work practice has not only negated its social roots, but also deprived both client and worker of a valuable source of help. Chinese shamanic healing is contrasted with casework practice and implications are drawn for re-establishing the `social' dimension in social work practice.postprin

Object-based coding for plenoptic videos

A new object-based coding system for a class of dynamic image-based representations called plenoptic videos (PVs) is proposed. PVs are simplified dynamic light fields, where the videos are taken at regularly spaced locations along line segments instead of a 2-D plane. In the proposed object-based approach, objects at different depth values are segmented to improve the rendering quality. By encoding PVs at the object level, desirable functionalities such as scalability of contents, error resilience, and interactivity with an individual image-based rendering (IBR) object can be achieved. Besides supporting the coding of texture and binary shape maps for IBR objects with arbitrary shapes, the proposed system also supports the coding of grayscale alpha maps as well as depth maps (geometry information) to respectively facilitate the matting and rendering of the IBR objects. Both temporal and spatial redundancies among the streams in the PV are exploited to improve the coding performance, while avoiding excessive complexity in selective decoding of PVs to support fast rendering speed. Advanced spatial/temporal prediction methods such as global disparity-compensated prediction, as well as direct prediction and its extensions are developed. The bit allocation and rate control scheme employing a new convex optimization-based approach are also introduced. Experimental results show that considerable improvements in coding performance are obtained for both synthetic and real scenes, while supporting the stated object-based functionalities. © 2006 IEEE.published_or_final_versio

On object-based compression for a class of dynamic image-based representations

An object-based compression scheme for a class of dynamic image-based representations called "plenoptic videos" (PVs) is studied in this paper. PVs are simplified dynamic light fields in which the videos are taken at regularly spaced locations along a line segment instead of a 2-D plane. To improve the rendering quality in scenes with large depth variations and support the functionalities at the object level for rendering, an object-based compression scheme is employed for the coding of PVs. Besides texture and shape information, the compression of geometry information in the form of depth maps is also supported. The proposed compression scheme exploits both the temporal and spatial redundancy among video object streams in the PV to achieve higher compression efficiency. Experimental results show that considerable improvements in coding performance are obtained for both synthetic and real scenes. Moreover, object-based functionalities such as rendering individual image-based objects are also illustrated. © 2005 IEEE.published_or_final_versio

An object-based approach to plenoptic videos

This paper proposes an object-based approach to plenoptic videos, where the plenoptic video sequences are segmented into image-based rendering (IBR) objects each with its image sequence, depth map and other relevant information such as shape information. This allows desirable functionalities such as scalability of contents, error resilience, and interactivity with individual IBR objects to be supported. A portable capturing system consisting of two linear camera arrays, each hosting 6 JVC video cameras, was developed to verify the proposed approach. Rendering and compression results of real-world scenes demonstrate the usefulness and good quality of the proposed approach. © 2005 IEEE.published_or_final_versio