bluuebunny/crossref_metadata_2025 huggingface dataset:
Cortactin Recruitment by Enterohemorrhagic
Escherichia coli
O157:H7 during Infection In Vitro and Ex Vivo
Authors: Mousnier Aurelie , Whale Andrew D. , Schüller Stephanie , Leong John M. , Phillips Alan D. , Frankel Gad
Published: August 2008

Enterohemorrhagic
Escherichia coli
(EHEC) O157:H7 is an important human pathogen that colonizes the gut mucosa via attaching and effacing (A/E) lesions; A/E lesion formation in vivo and ex vivo is dependent on the type III secretion system (T3SS) effector Tir. Infection of cultured cells by EHEC leads to induction of localized actin polymerization, which is dependent on Tir and a second T3SS effector protein, TccP, also known as EspF
U
. Recently, cortactin was shown to bind both the N terminus of Tir and TccP via its SH3 domain and to play a role in EHEC-triggered actin polymerization in vitro. In this study, we investigated the recruitment of cortactin to the site of EHEC adhesion during infection of in vitro-cultured cells and mucosal surfaces ex vivo (using human terminal ileal in vitro organ cultures [IVOC]). We have shown that cortactin is recruited to the site of EHEC adhesion in vitro downstream of TccP and N-WASP. Deletion of the entire N terminus of Tir or replacing the N-terminal polyproline region with alanines did not abrogate actin polymerization or cortactin recruitment. In contrast, recruitment of cortactin to the site of EHEC adhesion in IVOC is TccP independent. These results imply that cortactin is recruited to the site of EHEC adhesion in vitro and ex vivo by different mechanisms and suggest that cortactin might have a role during EHEC infection of mucosal surfaces.
Two-Partner Secretion Systems of
Neisseria meningitidis
Associated with Invasive Clonal Complexes
Authors: van Ulsen Peter , Rutten Lucy , Feller Moniek , Tommassen Jan , van der Ende Arie
Published: August 2008

The two-partner secretion (TPS) pathway is widespread among gram-negative bacteria and facilitates the secretion of very large and often virulence-related proteins. TPS systems consist of a secreted TpsA protein and a TpsB protein involved in TpsA transport across the outer membrane. Sequenced
Neisseria meningitidis
genomes contain up to five TpsA- and two TpsB-encoding genes. Here, we investigated the distribution of TPS-related open reading frames in a collection of disease isolates. Three distinct TPS systems were identified among meningococci. System 1 was ubiquitous, while systems 2 and 3 were significantly more prevalent among isolates of hyperinvasive clonal complexes than among isolates of poorly invasive clonal complexes. In laboratory cultures, systems 1 and 2 were expressed. However, several sera from patients recovering from disseminated meningococcal disease recognized the TpsAs of systems 2 and 3, indicating the expression of these systems during infection. Furthermore, we showed that the major secreted TpsAs of systems 1 and 2 depend on their cognate TpsBs for transport across the outer membrane and that the system 1 TpsAs undergo processing. Together, our data indicate that TPS systems may contribute to the virulence of
N. meningitidis
.
TrxR, a New CovR-Repressed Response Regulator That Activates the Mga Virulence Regulon in Group A Streptococcus
Authors: Leday Temekka V. , Gold Kathryn M. , Kinkel Traci L. , Roberts Samantha A. , Scott June R. , McIver Kevin S.
Published: August 2008

Coordinate regulation of virulence factors by the group A streptococcus (GAS)Streptococcus pyogenesis important in this pathogen's ability to cause disease. To further elucidate the regulatory network in this human pathogen, the CovR-repressed two-component system (TCS)trxSRwas chosen for further analysis based on its homology to a virulence-related TCS inStreptococcus pneumoniae. In a murine skin infection model, an insertion mutation in the response regulator gene,trxR, led to a significant reduction in lesion size, lesion severity, and lethality. Curing thetrxRmutation restored virulence comparable to the wild-type strain. ThetrxSRoperon was defined in vivo, and CovR was found to directly repress its promoter in vitro. DNA microarray analysis established that TrxR activates transcription of Mga-regulated virulence genes, which may explain the virulence attenuation of thetrxRmutant. This regulation appears to occur by activation of themgapromoter, Pmga, as demonstrated by analysis of a luciferase reporter fusion. Complementation of thetrxRmutant withtrxRon a plasmid restored expression of Mga regulon genes and restored virulence in the mouse model to wild-type levels. TrxR is the first TCS shown to regulate Mga expression. Because it is CovR repressed, TrxR defines a new pathway by which CovR can influence Mga to affect pathogenesis in the GAS.
Development and Transfer of Plasmid-Mediated Antimicrobial Resistance in Edwardsiella ictaluri
Authors: Waltman II W. Douglas , Shotts Emmett B. , Wooley Richard E.
Published: August 2008

Edwardsiella ictaluri were found to develop and transfer plasmid-mediated antimicrobial resistance. All isolates tested were found to receive resistance(R)-plasmids at frequencies ranging from 10−3 to 10−6. The antimicrobials to which E. ictaluri became resistant included tetracycline and Romet, the only two antibiotics cleared for use in channel catfish (Ictalurus punctatus) culture. The frequency of plasmid transfer appeared to be temperature related, with higher frequencies at 30 °C than at 20 or 37 °C. E. ictaluri having received an R-plasmid was shown to transfer the plasmid to Escherichia coli and Yersinia ruckeri at fairly high frequencies.
Survival, Ocean Growth, and Ocean Distribution of Differentially Timed Releases of Hatchery Coho Salmon (Oncorhynchus kisutch)
Authors: Mathews Stephen B. , Ishida Yukimasa
Published: August 2008

Estimates of growth rates in early ocean life and length frequency distributions at time of release for adult survivors were inferred from scale measurements for lots of coho salmon (Oncorhynchus kisutch) released at several dates from a Columbia River hatchery (Big Creek) and a southern Oregon hatchery (Coos Bay). Analysis of these measurements failed to support either of two literature-suggested hypotheses for the variability of marine survival of hatchery coho by date of release: (1) intraseasonal variability of food supply during early marine life; and (2) intraseasonally improving ability of smaller individuals within release lots to convert to salt water. Marine survival improved substantially with date of release at both hatcheries. However, fish released earliest, which survived relatively poorly, grew as fast in early marine life as fish released later, which survived better. Thus, poor survival of the early released fish did not appear related to lack of food at early ocean life. For the Big Creek hatchery, no significant differences were seen between the mean lengths at date of release and the mean release-date lengths of adult survivors back calculated from their scales, for lots released on May 5, June 3, and July 2. Apparently, small and large fish of each lot survived with equal probability. For the Coos Bay hatchery, the mean release-date lengths of adult survivors were significantly larger than the mean lengths of all fish released, for each of six lots released between early June and late July. Thus, large fish apparently survived better than small ones within each of these six lots. But there was no seasonal trend in survivability of small fish relative to large ones, contrary to hypothesis (2)
UNIFORMLY ACCELERATING REFERENCE FRAMES AND THE EQUIVALENCE PRINCIPLE
Authors: HUANG CHAO-GUANG
Published: August 2008

In addition to the well-known Møller frame (or Rindler frame), we may construct another frame to describe the uniformly accelerating system. In the new frame, all "static" (i.e. spatial coordinates keeping constant) observers have the same proper acceleration but each has his own horizon. In contrast, the proper acceleration of a static observer in the Møller frame (or Rindler frame) depends on his position, but the horizon is (static-) observer-independent. We argue that the new uniformly accelerating reference frame is more suitable than the Møller frame to describe the system in an accelerating spacecraft. It is possible to distinguish the Møller frame and the new frame by high-precision experiments (such as arrival-time- and/or redshift-measurements) in an accelerating spacecraft. When the non-relativistic limit is taken, the second law of mechanics and Schrödinger equation in the new uniformly accelerating frame are all different from those in the Møller frame. The effects on the equivalence principle are discussed. We argue that even when the space–time curvature is ignored, it is still possible in some sense to distinguish gravity from acceleration at the next leading order.
DATA ANALYSIS OF GRAVITATIONAL WAVES USING A NETWORK OF DETECTORS
Authors: WEN LINQING
Published: August 2008

Several large-scale gravitational wave (GW) interferometers have achieved long term operation at design sensitivity. Questions arise on how to best combine all available data from detectors of different sensitivities for detection, consistency check or veto, localization and waveform extraction. We show that these problems can be formulated using the singular value decomposition (SVD)1 method. We present techniques based on the SVD method for (1) detection statistic, (2) stable solutions to waveforms, (3) null-stream construction for an arbitrary number of detectors, and (4) source localization for GWs of unknown waveforms.
REDISCOVERING THE CO-OCCURRENCE PRINCIPLES OF VOWEL INVENTORIES: A COMPLEX NETWORK APPROACH
Authors: MUKHERJEE ANIMESH , CHOUDHURY MONOJIT , BASU ANUPAM , GANGULY NILOY , CHOWDHURY SHAMIK ROY
Published: August 2008

In this work, we attempt to capture patterns of co-occurrence across vowel systems and at the same time figure out the nature of the force leading to the emergence of such patterns. For this purpose, we define a weighted network where the vowels are the nodes and an edge between two nodes (read vowels) signifies their co-occurrence likelihood over the vowel inventories. Through this network we identify communities of vowels, which essentially reflect their patterns of co-occurrence across languages. We observe that in the communities formed by the frequently occurring vowels, the constituent nodes are largely uncorrelated in terms of their features and show that they are formed based on the principle of maximal perceptual contrast. However, in the rest of the communities, strong correlations are reflected among the constituent vowels with respect to their features, indicating that it is the principle of feature economy that binds them together. We validate the above observations by proposing a quantitative measure of perceptual contrast as well as feature economy and subsequently comparing the results obtained due to these quantifications with those where we assume that the vowel inventories had evolved just by chance.
SOME LIMITS OF STANDARD LINGUISTIC TYPOLOGY: THE CASE OF CYSOUW'S MODELS FOR THE FREQUENCIES OF THE SIX POSSIBLE ORDERINGS OF S, V AND O
Authors: FERRER-I-CANCHO RAMON
Published: August 2008

This article is a critical analysis of Michael Cysouw's comment "Linear Order as a Predictor of Word Order Regularities."
Planation surfaces in China: one hundred years of investigation
Authors: Zhang Ke
Published: August 2008

By introduction of the erosional cycle theory of W. M. Davis, Bailey Willis, an American geologist, began pioneering work on planation surfaces in northern China between 1903 and 1904. He identified two surfaces. Subsequently, the study of planation surfaces in northern China was continued by both Western and Chinese scientists, and this stimulated similar research in other parts of China. However, in the 1930s and 1940s the study of planation surfaces all but stopped because of the Japanese invasion of China, the civil war that followed, and again during the period of the ‘Cultural Revolution’ between 1966 and 1976. In the early 1960s the cycle theory proposed by Davis was much criticized, and with it the concept of the planation surface. However, from the 1980s, after careful re-examination of former criticisms, geomorphologists realized that the early concepts did have value and began to restudy planation surfaces over the whole of China. The most interesting research has been on planation surfaces preserved in the area of the Tibetan Plateau, which relates to uplift of the plateau and its impact on the environment.
The study of desert dunes in Australia
Authors: Twidale C. Rowland
Published: August 2008

Most of the early explorers were bewildered by the features they encountered in the Australian deserts, but Sturt's observations led him to speculate on the origin of the sand ridges that were so much a part of his desert experience. Scientific investigations of the dunes, however, awaited the twentieth century. In the 1930s Madigan made signal contributions to the understanding of the features, but he also raised as many problems as he resolved. Post-war investigations by King and those due to Wopfner, initially related but incidental to the search of oil and gas, have done much to clarify the dynamics of dune development. More recently, luminescence dating has allowed the sand ridges, as well as periods of lake fill and alluviation, to be dated with some confidence. Chronological research has been extended to include the major palaeodunefields of southern Australia.
Early geological investigations of the Pleistocene Tamala Limestone, Western Australia
Authors: Mayer Wolf
Published: August 2008

The first geological studies of the Quaternary deposits, which crop out extensively along the coast of Western Australia, were carried out by members of English and French expeditions of discovery, between 1791 and 1836. The exploring parties included scholars with a background in geology, zoology and botany, as well as knowledgeable surgeons and sea captains with a strong interest in the natural sciences. Their collective work established the continuity, over vast distances, of a sequence of sedimentary rocks composed of quartz grains and shell debris, which today form the major part of the Tamala Limestone sequence. Their observations of the internal features of these rocks led some among them to develop views on the nature and origin of the cementing substance that bonds sand grains and shell debris in sedimentary layers and in concretions. There was disagreement among successive parties of visitors on the nature and origin of rhizoliths and other petrified woody matter in calcareous rocks. The finding of well-preserved sea shells in rocks now above sea level provided convincing evidence to investigators that the ocean had, in recent times, retreated from the land. The discovery of species of mollusc, known to be extinct in Europe, raised questions about an assumed worldwide extent of sedimentary sequences.
Questions of periodization and Adolphe von Morlot's contribution to the term and the concept ‘
Quaternär
’ (1854)
Authors: Klemun Marianne
Published: August 2008

Questions concerning periodization in geology are obviously still with us, and the same goes for the relationships of time, change and discontinuity. The fact that such questions are debated repeatedly in both history and geology is illustrated by the extensive discussion in recent years about the use of the term ‘Quaternary’ as a stratigraphic unit. Thus periodization is not merely a philosophical issue. Neither does it belong solely to the sociology or politics of science. Rather it must be seen as an essential instrument and an integral part of an on-going discussion of fundamental ideas about time in general.

Several texts state that it was Adolphe Morlot (1820–1867) who coined the term ‘Quaternary’, but in fact there were earlier usages, with different meanings. This paper discusses not so much the ‘invention’ of the term Quaternary, but its range of meaning during the early phase of its introduction and development, in order to give and appropriate categorization of Morlot's specific contribution and the reason why he introduce the term
Quaternär
. The discussion is based to a considerable extent on correspondence between Morlot and Friedrich Simony (1813–1896) of Vienna University.
The Spokane Flood debates: historical background and philosophical perspective
Authors: Baker Victor R.
Published: August 2008

The 1920s–1930s debates over the origin of the ‘Channeled Scabland’ landscape of eastern Washington, northwestern USA, focused on the cataclysmic flooding hypothesis of J Harlen Bretz. During the summer of 1922, Bretz began leading field parties of advanced University of Chicago students into the region. In his first paper, published in the
Bulletin of the Geological Society of America
, Bretz took special care not to mention cataclysmic origins. However, in a subsequent paper in the
Journal of Geology
, to the editorial board of which he had recently been added, Bretz formally described his hypothesis that an immense late Pleistocene flood, which he named the ‘Spokane Flood’, had derived from the margins of the nearby Cordilleran Ice Sheet. This cataclysm neatly accounted for numerous interrelated aspects of the Channeled Scabland landscape and nearby regions. Nevertheless, the geological community largely resisted Bretz's hypothesis for decades, despite his enthusiastic and eloquent defence thereof. Resolution of the controversy came gradually, initially through the recognition by J. T. Pardee of a plausible source for the flooding: ice-dammed Pleistocene glacial Lake Missoula in northern Idaho and western Montana. Eventually, by the 1960s, the field evidence for cataclysmic flooding became overwhelming, and physical processes were found to be completely consistent with that evidence. The controversy is of philosophical interest in regard to its documentation of the attitudes of geologists toward hypotheses, which illustrate aspects of geological reasoning that are distinctive in degree from those of other sciences.
Česlovas Pakuckas (or Czesław Pachucki): pioneer of modern glaciomorphology in Lithuania and Poland
Authors: Gaigalas Algirdas , Graniczny Marek , Satkūnas Jonas , Urban Halina
Published: August 2008

The contributions of the Lithuanian geologist Česlovas Pakuckas (1898–1956) (in Poland – Czesław Pachucki) to Pleistocene geology are of major significance, and he is regarded as the pioneer of modern glaciomorphological investigations of the Baltic marginal highlands in Lithuania and Poland. Pakuckas published his first paper on the glacial morphology of south Lithuania in 1934, followed in 1936 with one on the orientation marginal moraines in the east Lithuanian highlands and their origin, and in 1938 with another on the glacial morphology of south Lithuania. His ideas on glacial morphology were presented at the First Conference of Lithuanian and Latvian geologists held in Kaunas in 1940. Working in Poland after World War II, Pakuckas continued his glaciomorphological research and compiled data on the correlation of end moraines of NE Poland and south Lithuania with those in west Belarus as well as the Peribalticum. He concluded that during the Last Glaciation, the continental glacier was not a single ice sheet but consisted of a number of flows, each dependent on topography and each with its specific glacial centre. In Lithuania, Pakuckas defined one large field of lateral moraines, the so-called Baltic Highland consisting of the Sūduva, Dzūkija and Aukštaitija highlands. He traced this formation SW as the Mazurian arc of lateral moraines (in NE Poland) and found that the Švenčionys–Naroch or north Belarus field of lateral moraines extend to the NE of the Baltic Highland.
Improved seam carving for video retargeting
Authors: Rubinstein Michael , Shamir Ariel , Avidan Shai
Published: August 2008

Video, like images, should support content aware resizing. We present video retargeting using an improved seam carving operator. Instead of removing 1D seams from 2D images we remove 2D seam manifolds from 3D space-time volumes. To achieve this we replace the dynamic programming method of seam carving with graph cuts that are suitable for 3D volumes. In the new formulation, a seam is given by a minimal cut in the graph and we show how to construct a graph such that the resulting cut is a valid seam. That is, the cut is monotonic and connected. In addition, we present a novel energy criterion that improves the visual quality of the retargeted images and videos. The original seam carving operator is focused on removing seams with the least amount of energy, ignoring energy that is introduced into the images and video by applying the operator. To counter this, the new criterion is looking forward in time - removing seams that introduce the least amount of energy into the retargeted result. We show how to encode the improved criterion into graph cuts (for images and video) as well as dynamic programming (for images). We apply our technique to images and videos and present results of various applications.
Robust treatment of simultaneous collisions
Authors: Harmon David , Vouga Etienne , Tamstorf Rasmus , Grinspun Eitan
Published: August 2008

Robust treatment of complex collisions is a challenging problem in cloth simulation. Some state of the art methods resolve collisions iteratively, invoking a fail-safe when a bound on iteration count is exceeded. The best-known fail-safe rigidifies the contact region, causing simulation artifacts. We present a fail-safe that cancels impact but not sliding motion, considerably reducing artificial dissipation. We equip the proposed fail-safe with an approximation of Coulomb friction, allowing finer control of sliding dissipation.
Example-based dynamic skinning in real time
Authors: Shi Xiaohan , Zhou Kun , Tong Yiying , Desbrun Mathieu , Bao Hujun , Guo Baining
Published: August 2008

In this paper we present an approach to enrich skeleton-driven animations with physically-based secondary deformation in real time. To achieve this goal, we propose a novel, surface-based deformable model that can interactively emulate the dynamics of both low-and high-frequency volumetric effects. Given a surface mesh and a few sample sequences of its physical behavior, a set of motion parameters of the material are learned during an off-line preprocessing step. The deformable model is then applicable to any given skeleton-driven animation of the surface mesh. Additionally, our dynamic skinning technique can be entirely implemented on GPUs and executed with great efficiency. Thus, with minimal changes to the conventional graphics pipeline, our approach can drastically enhance the visual experience of skeleton-driven animations by adding secondary deformation in real time.
Dual scattering approximation for fast multiple scattering in hair
Authors: Zinke Arno , Yuksel Cem , Weber Andreas , Keyser John
Published: August 2008

When rendering light colored hair, multiple fiber scattering is essential for the right perception of the overall hair color. In this context, we present a novel technique to efficiently approximate multiple fiber scattering for a full head of human hair or a similar fiber based geometry. In contrast to previous ad-hoc approaches, our method relies on the physically accurate concept of the Bidirectional Scattering Distribution Functions and gives physically plausible results with no need for parameter tweaking. We show that complex scattering effects can be approximated very well by using aggressive simplifications based on this theoretical model. When compared to unbiased Monte-Carlo path tracing, our approximations preserve photo-realism in most settings but with rendering times at least two-orders of magnitude lower. Time and space complexity are much lower compared to photon mapping-based techniques and we can even achieve realistic results in real-time on a standard PC with consumer graphics hardware.
Face swapping
Authors: Bitouk Dmitri , Kumar Neeraj , Dhillon Samreen , Belhumeur Peter , Nayar Shree K.
Published: August 2008

In this paper, we present a complete system for automatic face replacement in images. Our system uses a large library of face images created automatically by downloading images from the internet, extracting faces using face detection software, and aligning each extracted face to a common coordinate system. This library is constructed off-line, once, and can be efficiently accessed during face replacement. Our replacement algorithm has three main stages. First, given an input image, we detect all faces that are present, align them to the coordinate system used by our face library, and select candidate face images from our face library that are similar to the input face in appearance and pose. Second, we adjust the pose, lighting, and color of the candidate face images to match the appearance of those in the input image, and seamlessly blend in the results. Third, we rank the blended candidate replacements by computing a match distance over the overlap region. Our approach requires no 3D model, is fully automatic, and generates highly plausible results across a wide range of skin tones, lighting conditions, and viewpoints. We show how our approach can be used for a variety of applications including face de-identification and the creation of appealing group photographs from a set of images. We conclude with a user study that validates the high quality of our replacement results, and a discussion on the current limitations of our system.
AppProp
Authors: An Xiaobo , Pellacini Fabio
Published: August 2008

We present an intuitive and efficient method for editing the appearance of complex spatially-varying datasets, such as images and measured materials. In our framework, users specify rough adjustments that are refined interactively by enforcing the policy that similar edits are applied to spatially-close regions of similar appearance. Rather than proposing a specific user interface, our method allows artists to quickly and imprecisely specify the initial edits with any method or workflow they feel most comfortable with. An energy optimization formulation is used to propagate the initial rough adjustments to the final refined ones by enforcing the editing policy over all pairs of points in the dataset. We show that this formulation is equivalent to solving a large linear system defined by a dense matrix. We derive an approximate algorithm to compute such a solution interactively by taking advantage of the inherent structure of the matrix. We demonstrate our approach by editing images, HDR radiance maps, and measured materials. Finally, we show that our framework generalizes prior methods while providing significant improvements in generality, robustness and efficiency.
Computing geometry-aware handle and tunnel loops in 3D models
Authors: Dey Tamal K. , Li Kuiyu , Sun Jian , Cohen-Steiner David
Published: August 2008

Many applications such as topology repair, model editing, surface parameterization, and feature recognition benefit from computing loops on surfaces that wrap around their 'handles' and 'tunnels'. Computing such loops while optimizing their geometric lengths is difficult. On the other hand, computing such loops without considering geometry is easy but may not be very useful. In this paper we strike a balance by computing topologically correct loops that are also geometrically relevant. Our algorithm is a novel application of the concepts from topological persistence introduced recently in computational topology. The usability of the computed loops is demonstrated with some examples in feature identification and topology simplification.
Bubbles alive
Authors: Hong Jeong-Mo , Lee Ho-Young , Yoon Jong-Chul , Kim Chang-Hun
Published: August 2008

We propose a hybrid method for simulating multiphase fluids such as bubbly water. The appearance of subgrid visual details is improved by incorporating a new bubble model based on smoothed particle hydrodynamics (SPH) into an Eulerian grid-based simulation that handles background flows of large bodies of water and air. To overcome the difficulty in simulating small bubbles in the context of the multiphase flows on a coarse grid, we heuristically model the interphase properties of water and air by means of the interactions between bubble particles. As a result, we can animate lively motion of bubbly water with small scale details efficiently.
Multiscale texture synthesis
Authors: Han Charles , Risser Eric , Ramamoorthi Ravi , Grinspun Eitan
Published: August 2008

Example-based texture synthesis algorithms have gained widespread popularity for their ability to take a single input image and create a perceptually similar non-periodic texture. However, previous methods rely on single input exemplars that can capture only a limited band of spatial scales. For example, synthesizing a continent-like appearance at a variety of zoom levels would require an impractically high input resolution. In this paper, we develop a multiscale texture synthesis algorithm. We propose a novel example-based representation, which we call an exemplar graph, that simply requires a few low-resolution input exemplars at different scales. Moreover, by allowing loops in the graph, we can create infinite zooms and infinitely detailed textures that are impossible with current example-based methods. We also introduce a technique that ameliorates inconsistencies in the user's input, and show that the application of this method yields improved interscale coherence and higher visual quality. We demonstrate optimizations for both CPU and GPU implementations of our method, and use them to produce animations with zooming and panning at multiple scales, as well as static gigapixel-sized images with features spanning many spatial scales.
Lapped solid textures
Authors: Takayama Kenshi , Okabe Makoto , Ijiri Takashi , Igarashi Takeo
Published: August 2008

We present a method for representing solid objects with spatially-varying oriented textures by repeatedly pasting solid texture exemplars. The underlying concept is to extend the 2D texture patch-pasting approach of lapped textures to 3D solids using a tetrahedral mesh and 3D texture patches. The system places texture patches according to the user-defined volumetric tensor fields over the mesh to represent oriented textures. We have also extended the original technique to handle nonhomogeneous textures for creating solid models whose textural patterns change gradually along the depth fields. We identify several texture types considering the amount of anisotropy and spatial variation and provide a tailored user interface for each. With our simple framework, large-scale realistic solid models can be created easily with little memory and computational cost. We demonstrate the effectiveness of our approach with several examples including trees, fruits, and vegetables.
Glare aware photography
Authors: Raskar Ramesh , Agrawal Amit , Wilson Cyrus A. , Veeraraghavan Ashok
Published: August 2008

Glare arises due to multiple scattering of light inside the camera's body and lens optics and reduces image contrast. While previous approaches have analyzed glare in 2D image space, we show that glare is inherently a 4D ray-space phenomenon. By statistically analyzing the ray-space inside a camera, we can classify and remove glare artifacts. In ray-space, glare behaves as high frequency noise and can be reduced by outlier rejection. While such analysis can be performed by capturing the light field inside the camera, it results in the loss of spatial resolution. Unlike light field cameras, we do not need to reversibly encode the spatial structure of the ray-space, leading to simpler designs. We explore masks for uniform and non-uniform ray sampling and show a practical solution to analyze the 4D statistics without significantly compromising image resolution. Although diffuse scattering of the lens introduces 4D low-frequency glare, we can produce useful solutions in a variety of common scenarios. Our approach handles photography looking into the sun and photos taken without a hood, removes the effect of lens smudges and reduces loss of contrast due to camera body reflections. We show various applications in contrast enhancement and glare manipulation.
Light field transfer
Authors: Cossairt Oliver , Nayar Shree , Ramamoorthi Ravi
Published: August 2008

We present a novel image-based method for compositing real and synthetic objects in the same scene with a high degree of visual realism. Ours is the first technique to allow global illumination and near-field lighting effects between both real and synthetic objects at interactive rates, without needing a geometric and material model of the real scene. We achieve this by using a light field interface between real and synthetic components---thus, indirect illumination can be simulated using only two 4D light fields, one captured from and one projected onto the real scene. Multiple bounces of interreflections are obtained simply by iterating this approach. The interactivity of our technique enables its use with time-varying scenes, including dynamic objects. This is in sharp contrast to the alternative approach of using 6D or 8D light transport functions of real objects, which are very expensive in terms of acquisition and storage and hence not suitable for real-time applications. In our method, 4D radiance fields are simultaneously captured and projected by using a lens array, video camera, and digital projector. The method supports full global illumination with restricted object placement, and accommodates moderately specular materials. We implement a complete system and show several example scene compositions that demonstrate global illumination effects between dynamic real and synthetic objects. Our implementation requires a single point light source and dark background.
Discrete elastic rods
Authors: Bergou Miklós , Wardetzky Max , Robinson Stephen , Audoly Basile , Grinspun Eitan
Published: August 2008

We present a discrete treatment of adapted framed curves, parallel transport, and holonomy, thus establishing the language for a discrete geometric model of thin flexible rods with arbitrary cross section and undeformed configuration. Our approach differs from existing simulation techniques in the graphics and mechanics literature both in the kinematic description---we represent the material frame by its angular deviation from the natural Bishop frame---as well as in the dynamical treatment---we treat the centerline as dynamic and the material frame as quasistatic. Additionally, we describe a manifold projection method for coupling rods to rigid-bodies and simultaneously enforcing rod inextensibility. The use of quasistatics and constraints provides an efficient treatment for stiff twisting and stretching modes; at the same time, we retain the dynamic bending of the centerline and accurately reproduce the coupling between bending and twisting modes. We validate the discrete rod model via quantitative buckling, stability, and coupled-mode experiments, and via qualitative knot-tying comparisons.
Dynamic range independent image quality assessment
Authors: Aydin Tunç Ozan , Mantiuk Rafał , Myszkowski Karol , Seidel Hans-Peter
Published: August 2008

The diversity of display technologies and introduction of high dynamic range imagery introduces the necessity of comparing images of radically different dynamic ranges. Current quality assessment metrics are not suitable for this task, as they assume that both reference and test images have the same dynamic range. Image fidelity measures employed by a majority of current metrics, based on the difference of pixel intensity or contrast values between test and reference images, result in meaningless predictions if this assumption does not hold. We present a novel image quality metric capable of operating on an image pair where both images have arbitrary dynamic ranges. Our metric utilizes a model of the human visual system, and its central idea is a new definition of visible distortion based on the detection and classification of visible changes in the image structure. Our metric is carefully calibrated and its performance is validated through perceptual experiments. We demonstrate possible applications of our metric to the evaluation of direct and inverse tone mapping operators as well as the analysis of the image appearance on displays with various characteristics.
Progressive inter-scale and intra-scale non-blind image deconvolution
Authors: Yuan Lu , Sun Jian , Quan Long , Shum Heung-Yeung
Published: August 2008

Ringing is the most disturbing artifact in the image deconvolution. In this paper, we present a progressive inter-scale and intra-scale non-blind image deconvolution approach that significantly reduces ringing. Our approach is built on a novel edge-preserving deconvolution algorithm called
bilateral Richardson-Lucy (BRL)
which uses a large spatial support to handle large blur. We progressively recover the image from a coarse scale to a fine scale (inter-scale), and progressively restore image details within every scale (intra-scale). To perform the inter-scale deconvolution, we propose a
joint bilateral Richardson-Lucy (JBRL)
algorithm so that the recovered image in one scale can guide the deconvolution in the next scale. In each scale, we propose an iterative residual deconvolution to progressively recover image details. The experimental results show that our progressive deconvolution can produce images with very little ringing for large blur kernels.
Conformal equivalence of triangle meshes
Authors: Springborn Boris , Schröder Peter , Pinkall Ulrich
Published: August 2008

We present a new algorithm for conformal mesh parameterization. It is based on a precise notion of
discrete conformal equivalence
for triangle meshes which mimics the notion of conformal equivalence for smooth surfaces. The problem of finding a flat mesh that is discretely conformally equivalent to a given mesh can be solved efficiently by minimizing a convex energy function, whose Hessian turns out to be the well known cot-Laplace operator. This method can also be used to map a surface mesh to a parameter domain which is flat except for isolated cone singularities, and we show how these can be placed automatically in order to reduce the distortion of the parameterization. We present the salient features of the theory and elaborate the algorithms with a number of examples.
Group motion editing
Authors: Kwon Taesoo , Lee Kang Hoon , Lee Jehee , Takahashi Shigeo
Published: August 2008

Animating a crowd of characters is an important problem in computer graphics. The latest techniques enable highly realistic group motions to be produced in feature animation films and video games. However, interactive methods have not emerged yet for editing the existing group motion of multiple characters. We present an approach to editing group motion as a whole while maintaining its neighborhood formation and individual moving trajectories in the original animation as much as possible. The user can deform a group motion by pinning or dragging individuals. Multiple group motions can be stitched or merged to form a longer or larger group motion while avoiding collisions. These editing operations rely on a novel graph structure, in which vertices represent positions of individuals at specific frames and edges encode neighborhood formations and moving trajectories. We employ a shape-manipulation technique to minimize the distortion of relative arrangements among adjacent vertices while editing the graph structure. The usefulness and flexibility of our approach is demonstrated through examples in which the user creates and edits complex crowd animations interactively using a collection of group motion clips.
Interactive simulation of stylized human locomotion
Authors: da Silva Marco , Abe Yeuhi , Popović Jovan
Published: August 2008

Animating natural human motion in dynamic environments is difficult because of complex geometric and physical interactions. Simulation provides an automatic solution to parts of this problem, but it needs control systems to produce lifelike motions. This paper describes the systematic computation of controllers that can reproduce a range of locomotion styles in interactive simulations. Given a reference motion that describes the desired style, a derived control system can reproduce that style in simulation and in new environments. Because it produces high-quality motions that are both geometrically and physically consistent with simulated surroundings, interactive animation systems could begin to use this approach along with more established kinematic methods.
Fluorescent immersion range scanning
Authors: Hullin Matthias B. , Fuchs Martin , Ihrke Ivo , Seidel Hans-Peter , Lensch Hendrik P. A.
Published: August 2008

The quality of a 3D range scan should not depend on the surface properties of the object. Most active range scanning techniques, however, assume a diffuse reflector to allow for a robust detection of incident light patterns. In our approach we embed the object into a fluorescent liquid. By analyzing the light rays that become visible due to fluorescence rather than analyzing their reflections off the surface, we can detect the intersection points between the projected laser sheet and the object surface for a wide range of different materials. For transparent objects we can even directly depict a slice through the object in just one image by matching its refractive index to the one of the embedding liquid. This enables a direct sampling of the object geometry without the need for computational reconstruction. This way, a high-resolution 3D volume can be assembled simply by sweeping a laser plane through the object. We demonstrate the effectiveness of our light sheet range scanning approach on a set of objects manufactured from a variety of materials and material mixes, including dark, translucent and transparent objects.
Diffusion curves
Authors: Orzan Alexandrina , Bousseau Adrien , Winnemöller Holger , Barla Pascal , Thollot Joëlle , Salesin David
Published: August 2008

We describe a new vector-based primitive for creating smooth-shaded images, called the
diffusion curve
. A diffusion curve partitions the space through which it is drawn, defining different colors on either side. These colors may vary smoothly along the curve. In addition, the sharpness of the color transition from one side of the curve to the other can be controlled. Given a set of diffusion curves, the final image is constructed by solving a Poisson equation whose constraints are specified by the set of gradients across all diffusion curves. Like all vector-based primitives, diffusion curves conveniently support a variety of operations, including geometry-based editing, keyframe animation, and ready stylization. Moreover, their representation is compact and inherently resolution-independent. We describe a GPU-based implementation for rendering images defined by a set of diffusion curves in realtime. We then demonstrate an interactive drawing system for allowing artists to create artworks using diffusion curves, either by drawing the curves in a freehand style, or by tracing existing imagery. The system is simple and intuitive: we show results created by artists after just a few minutes of instruction. Furthermore, we describe a completely automatic conversion process for taking an image and turning it into a set of diffusion curves that closely approximate the original image content.
Feedback control of cumuliform cloud formation based on computational fluid dynamics
Authors: Dobashi Yoshinori , Kusumoto Katsutoshi , Nishita Tomoyuki , Yamamoto Tsuyoshi
Published: August 2008

Clouds play an important role for creating realistic images of outdoor scenes. In order to generate realistic clouds, many methods have been developed for modeling and animating clouds. One of the most effective approaches for synthesizing realistic clouds is to simulate cloud formation processes based on the atmospheric fluid dynamics. Although this approach can create realistic clouds, the resulting shapes and motion depend on many simulation parameters and the initial status. Therefore, it is very difficult to adjust those parameters so that the clouds form the desired shapes. This paper addresses this problem and presents a method for controlling the simulation of cloud formation. In this paper, we focus on controlling cumuliform cloud formation. The user specifies the overall shape of the clouds. Then, our method automatically adjusts parameters during the simulation in order to generate clouds forming the specified shape. Our method can generate realistic clouds while their shapes closely match to the desired shape.
Shading-based surface editing
Authors: Gingold Yotam , Zorin Denis
Published: August 2008

We present a system for free-form surface modeling that allows a user to modify a shape by changing its rendered, shaded image using stroke-based drawing tools. User input is translated into a set of tangent and positional constraints on the surface. A new shape, whose rendered image closely approximates user input, is computed using an efficient and stable surface optimization procedure. We demonstrate how several types of free-form surface edits which may be difficult to cast in terms of standard deformation approaches can be easily performed using our system.
Data-driven modeling of skin and muscle deformation
Authors: Park Sang Il , Hodgins Jessica K.
Published: August 2008

In this paper, we present a data-driven technique for synthesizing skin deformation from skeletal motion. We first create a database of dynamic skin deformations by recording the motion of the surface of the skin with a very large set of motion capture markers. We then build a statistical model of the deformations by dividing them into two parts: static and dynamic. Static deformations are modeled as a function of pose. Dynamic deformations are caused by the actions of the muscles as they move the joints and the inertia of muscles and fat. We approximate these effects by fitting a set of dynamic equations to the pre-recorded data. We demonstrate the viability of this approach by generating skin deformations from the skeletal motion of an actor. We compare the generated animation both to synchronized video of the actor and to ground truth animation created directly from the large marker set.
Interactive procedural street modeling
Authors: Chen Guoning , Esch Gregory , Wonka Peter , Müller Pascal , Zhang Eugene
Published: August 2008

This paper addresses the problem of interactively modeling large street networks. We introduce an intuitive and flexible modeling framework in which a user can create a street network from scratch or modify an existing street network. This is achieved through designing an underlying tensor field and editing the graph representing the street network. The framework is intuitive because it uses tensor fields to guide the generation of a street network. The framework is flexible because it allows the user to combine various global and local modeling operations such as brush strokes, smoothing, constraints, noise and rotation fields. Our results will show street networks and three-dimensional urban geometry of high visual quality.