A novel method for the automatic generation of a facial texture is proposed in this paper. Multiple pictures from the individual are combined to create the texture using a wavelet-based technique. The different tasks involved in the proposed method include: scaling, histogram equalization, deformation and merging. A set of particular feature points of the MPEG-4 standard for multimedia applications is used in the above mentioned tasks. In the merging stage, wavelet multiresolution decomposition of the images and filtering of the wavelet coefficients are performed to obtain a seamless texture. Finally, the resulting texture is mapped onto a 3D head model which has been adapted to the particular individual based on the same pictures. Since the proposed method relies on the MPEG-4 facial and body animation (FBA) standard, it can be easily integrated with applications using the same standard.

TwinFaces, a new technique for the automatic generation of facial textures is presented in this paper. Multiple views from the individual, taken under moderately controlled illumination conditions, are combined to create the seamless texture using a wavelet-based technique. Since the method relies on a set of particular feature points of the MPEG-4 facial and body animation (FBA) standard, it can be easily integrated with applications using the same standard. A post-processing technique for pictures taken outdoors has been also integrated into TwinFaces to compensate for non-uniform illumination conditions. The wavelet-based approach has shown to be more flexible than previous approaches to remove the artificial seam lines produced by the blending of the different views involved in the texture generation

Abstract When the critical path of a communication session between end points includes the actions of operating system kernels, there are attendant overheads. Along with other factors, such as functionality and flexibility, such overheads motivate and favor the implementation of communication protocols in user space. When implemented with threads, such protocols may hold the key to optimal communication performance and functionality. Based on implementations of reliable user‐space protocols supported by a threads framework, we focus on our experiences with internal threads' scheduling techniques and their potential impact on performance. We present scheduling strategies that enable threads to do both application‐level and communication‐related processing. With experiments performed on a Sun SPARC‐5 LAN environment, we show how different scheduling strategies yield different levels of application‐processing efficiency, communication latency and packet‐loss. This work forms part of a larger study on the implementation of multiple thread‐based protocols in a single address space, and the benefits of coupling protocols with applications. Copyright © 2005 John Wiley & Sons, Ltd.

Precise timing and asynchronous I/O are appealing features for many applications. Unix kernels provide such features on a per-process basis, using signals to communicate asynchronous events to applications. Per-process signals and timers are grossly inadequate for complex multithreaded applications that require per-thread signals and timers that operate at finer granularity. To respond to this need, we present a scheme that integrates asynchronous (Unix) signals with user-level threads, using the ARIADNE system as a platform. This is done with a view towards support for portable, multithreaded, and multiprotocol distributed applications, namely the CLAM (connectionless, lightweight, and multiway) communications library. In the same context, we propose the use of continuations as an efficient mechanism for reducing thread context-switching and busy-wait overheads in multithreaded protocols. Our proposal for integrating timers and signal-handling mechanisms not only solves problems related to race conditions, but also offers an efficient and flexible interface for timing and signalling threads. Copyright © 2006 John Wiley & Sons, Ltd.

In this paper, a Graphical User Interface for the automatic generation of a facial texture mapping from three orthogonal photos is presented. The proposed method is based on the composition of the two side views (previously deformed) and the front view. The deformation is performed using a set of particular FDP (Facial Definition Points) of the MPEG-4 standard for multimedia applications. To smooth out the boundaries caused by the merging of the orthogonal views, a wavelet-based multiresolution filtering technique is employed. This work is the first stage in the development of a toolbox for automatic facial cloning.

The use of adaptive algorithms such as Kalman filtering, LMS and RLS together with FIR model structures are very common and extensively analysed. In the interests of improved performance an extension of the FIR structure has been proposed in which the fixed poles are not all at the origin, but instead are chosen by prior knowledge to be close to where the true poles are. Existing FIR analysis would indicate that the noise and tracking properties of such a scheme are invariant to the choice of fixed pole location. This paper establishes both numerically and theoretically that in fact this is not the case. Instead, the dependence of fixed pole location is made explicit by deriving frequency domain expressions that are obtained by using new results on generalised Fourier series and generalised Toeplitz matrices.

We present results on the experimental design and development of a Connectionless, Lightweight, and Multiway (CLAM) communications environment. The system provides efficient and scalable multiprotocol support for distributed applications that use multimodal data. We present motivation behind design decisions for the CLAM system, and describe two simple, but effective scheduling algorithms for the simultaneous support of multiple, threads-based user-space protocols. One algorithm is readily portable to shared-memory multiprocessors, and enables two or more protocols to coexist within an OS-level process. We present experimental results on the performance of both algorithms.