Articulated Billboards for Video‐based Rendering

We present a novel representation and rendering method for free‐viewpoint video of human characters based on multiple input video streams. The basic idea is to approximate the articulated 3D shape of the human body using a subdivision into textured billboards along the skeleton structure. Billboards are clustered to fans such that each skeleton bone contains one billboard per source camera. We call this representation articulated billboards. In the paper we describe a semi‐automatic, data‐driven algorithm to construct and render this representation, which robustly handles even challenging acquisition scenarios characterized by sparse camera positioning, inaccurate camera calibration, low video resolution, or occlusions in the scene. First, for each input view, a 2D pose estimation based on image silhouettes, motion capture data, and temporal video coherence is used to create a segmentation mask for each body part. Then, from the 2D poses and the segmentation, the actual articulated billboard model is constructed by a 3D joint optimization and compensation for camera calibration errors. The rendering method includes a novel way of blending the textural contributions of each billboard and features an adaptive seam correction to eliminate visible discontinuities between adjacent billboards textures. Our articulated billboards do not only minimize ghosting artifacts known from conventional billboard rendering, but also alleviate restrictions to the setup and sensitivities to errors of more complex 3D representations and multiview reconstruction techniques. Our results demonstrate the flexibility and the robustness of our approach with high quality free‐viewpoint video generated from broadcast footage of challenging, uncontrolled environments.     

Locally Injective Mappings

Mappings and deformations are ubiquitous in geometry processing, shape modeling, and animation. Numerous deformation energies have been proposed to tackle problems like mesh parameterization and volumetric deformations. We present an algorithm that modifies any deformation energy to guarantee a locally injective mapping, i.e., without inverted elements. Our formulation can be used to compute continuous planar or volumetric piecewise‐linear maps and it uses a barrier term to prevent inverted elements. Differently from previous methods, we carefully design both the barrier term and the associated numerical techniques to be able to provide immediate feedback to the user, enabling interactive manipulation of inversion‐free mappings. Stress tests show that our method robustly handles extreme deformations where previous techniques converge very slowly or even fail. We demonstrate that enforcing local injectivity increases fidelity of the results in applications such as shape deformation and parameterization.     

Single-mode optical fibre microbending loss in a loose tube coating

45 km of single-mode fibre of differing detailed design has been loose-tube packaged under identical conditions. The spectral loss between 1.1 and 1.75 ?m was measured before and after packaging. The incremental loss thus deduced, and related to equivalent core size and ?n, provided information about fibre design for safe packaging.     

Accurate and efficient lighting for skinned models

In the context of real‐time, GPU‐based rendering of animated skinned meshes, we propose a new algorithm to compute surface normals with minimal overhead both in terms of the memory footprint and the required per‐vertex operations. By accounting for the variation of the skinning weights over the surface, we achieve a higher visual quality compared to the standard approximation ubiquitously used in video‐game engines and other real‐time applications. Our method supports Linear Blend Skinning and Dual Quaternion Skinning. We demonstrate the advantages of our technique on a variety of datasets and provide a complete open‐source implementation, including GLSL shaders.     

The CD40 TRAF family member interacting motif carries the information to rescue WEHI 231 cells from anti-IGM-induced growth arrest

Engagement of the antigen receptor on WEHI 231 murine B lymphoma cells leads to growth arrest and induction of apoptosis. Concomitant signaling through CD40 sustains proliferation and rescues the cells from apoptosis. At the molecular level, CD40 has been shown to activate nuclear factor kappaB (NF-kappaB) and stress-activated protein kinase (SAPK). The aim of our present study was to define the stretch of the CD40 cytoplasmic tail responsible for mediating these effects in WEHI 231 cells. Using recombinant retroviruses with the enhanced green fluorescent protein as selection marker we transduced WEHI 231 cells with chimeric molecules consisting of the extracellular and transmembrane region of human CD40 or rat CD4 and selected portions of the murine CD40 tail. Chimeric molecules with cytoplasmic fragments encompassing the "CD40 tumor necrosis factor-associated factor family member interacting motif" (TIM) were able to sustain growth and to uphold NF-kappaB activity as efficiently as the whole intracellular region of CD40. While the potential of the motif relative to the whole cytoplasmic tail was independent of the heterologous part of the chimeras it was strongly influenced by its distance to the membrane. Placing the 17-amino acid stretch of the motif too close to the membrane, i. e. only two or four amino acids apart, destroyed its capacity to mitigate the anti-IgM effect. Activation of SAPK through the chimeric molecules always correlated with their ability to activate NF-kappaB activity and to rescue the cells from apoptosis induced by antigen receptor ligation. Our data indicate that CD40-TIM carries most if not all of the information needed to deliver the signals responsible for sustaining growth in anti-IgM-stimulated WEHI 231 cells.     

Numerical calculation of the current through a vibrating capacitor

Contents The measurement of the contact potential difference with the so-called Kelvin probe or vibrating capacitor technique is one of the most sensitive measuring procedures in surface physics. This article describes the influence of the shape of the Kelvin probe on the measured current. Two models are investigated: The most simple one, a parallel plate-capacitor and a more realistic one, a sphereplate capacitor.

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Numerische Berechnung des Stromes durch einen schwingenden Kondensator

Übersicht Die Messung der Kontaktpotential-Differenz mit Hilfe der Kelvin-Sonde oder der Methode des schwingenden Kondensators ist eine der empfindlichsten Meßmethoden in der Oberflächenphysik. In diesem Artikel wird der Einfluß der Form der Kelvin-Sonde auf den gemessenen Strom dargestellt. Zwei Modelle werden untersucht: Ein sehr einfaches, der parallele Platenkondensator, und ein etwas praxisnäheres, die Kapazität zwischen einer Kugel und einer Platte.

     

Pattern‐Based Quadrangulation for N‐Sided Patches

We propose an algorithm to quadrangulate an N‐sided patch (2 ≤ N ≤ 6) with prescribed numbers of edge subdivisions at its boundary. Our algorithm is guaranteed to succeed for arbitrary valid input, which is proved using a canonical simplification of the input and a small set of topological patterns that are sufficient for supporting all possible cases. Our algorithm produces solutions with minimal number of irregular vertices by default, but it also allows the user to choose other feasible solutions by solving a set of small integer linear programs. We demonstrate the effectiveness of our algorithm by integrating it into a sketch‐based quad remeshing system. A reference C++ implementation of our algorithm is provided as a supplementary material.     

UV enhanced substrate conformal imprint lithography (UV-SCIL) technique for photonic crystals patterning in LED manufacturing

The global LED (light emitting diode) market reached 5 billion dollors in 2008 and will be driven towards 9 billion dollors by 2011 [1]. The current applications are dominated by portable device backlighting, e.g. cell phones, PDAs, GPS, laptop etc. In order to open the general lighting market doors the luminous efficiency needs to be improved significantly. Photonic crystal (PhC) structures in LEDs have been demonstrated to enhance light extraction efficiency on the wafer level by researchers [2]. However, there is still a great challenge to fabricate PhC structures on LED wafers cost-effectively. Nanoimprint lithography (NIL) [3] has attracted considerable attentions in this field due to its high resolution, high throughput and low cost of ownership (CoO). However, the current NIL techniques with rigid stamps rely strongly on the substrate flatness and the production atmosphere. Those factors hinder the integration of NIL into high volume production lines. UV-NIL with flexible stamps [4], e.g. PDMS stamps, allows the large-area imprint in a single step and is less-sensitive to the production atmosphere. However, the resolution is normally limited due to stamp distortion caused by imprint pressure.A novel NIL technique developed by Philips Research and Süss MicroTec, substrate conformal imprint lithography (SCIL), bridges the gap between UV-NIL with rigid stamp for best resolution and soft stamp for large-area patterning. Based on a cost-effective upgrade on Süss mask aligner, the capability can be enhanced to nanoimprint with resolution of down to sub-10 nm on an up to 6 inch area without affecting the established conventional optical lithographic processes on the machine. Benefit from the exposure unit on the mask aligners, the SCIL process is now extended with UV-curing option, which can help to improve the throughput dramatically. In this paper, the fabrication of photonic crystal structures with SCIL technique on Süss MA6 mask aligner is demonstrated. In addition, the industrialization considerations of UV-SCIL process in high volume manufacturing are briefly discussed.