bluuebunny/crossref_metadata_2025 huggingface dataset:
Resource Partitioning in Two Coexisting Sunfish: Pumpkinseed (Lepomis gibbosus) and Northern Longear Sunfish (Lepomis megalotis peltastes)
Authors: Laughlin Dennis R. , Werner Earl E.
Published: July 2010

Qualitative surveys of 22 lakes in southern Michigan indicated that relative abundances of the northern longear sunfish (Lepomis megalotis peltastes) and pumpkinseed (L. gibbosus) depended upon amount of plant cover and sediment type. The longear sunfish occurred only in lakes with marl sediments and regions of sparse vegetation cover. The pumpkinseed occurred in all lakes surveyed and increased in abundance in lakes with greater vegetation density and/or more organic sediments. Quantitative measurements of habitat and food use were made in five lakes with sympatric populations. Data from underwater transects indicated that large (> 75 mm standard length) longear sunfish occurred primarily in shallow regions containing moderate to low vegetation cover whereas large pumpkinseeds were concentrated in deeper areas with heavy vegetation cover. The smaller size-classes of both species occupied the vegetation in deeper areas of the littoral zone. Large longears consumed predominantly large, sediment-dwelling mayfly or odonate nymphs regardless of the lake or habitat types. Pumpkinseeds consumed mainly gastropods and other prey from the vegetation. Preliminary studies of seasonal food use indicated that the pumpkinseed and longear sunfish both consumed more food in the spring and exhibited greater overlap in diet during this period. The relationship between foraging behaviors of these two species and the types of prey consumed is discussed as well as the complications of assessing competition between species when food and habitat use are dependent on size.Key words: Habitat use, size-class, lake types, food overlap, competition, Lepomis, Michigan
A Procedure Using Modeling and Error Analysis for the Prediction of Lake Phosphorus Concentration from Land Use Information
Authors: Reckhow K. H. , Simpson J. T.
Published: July 2010

Recent work in the area of empirical lake modeling and error analysis has resulted in some useful methods for the assessment of lake trophic quality. These methods are incorporated into the procedure presented herein for the prediction of lake phosphorus concentration. The procedure is described in a step-by-step manner; it begins with the estimation of phosphorus flux from major land use types and ends with the estimation of trophic state from the phosphorus concentration prediction. A nonparametric error analysis is included to supplement the prediction of phosphorus concentration. This assessment of uncertainty is an indication of the value of the information provided by the model. The method may be easily applied to most north temperate lakes, and an example is presented to illustrate its use.Key words: eutrophication, lakes, model, error analysis, phosphorus, land use planning
Diel Activity Pattern and Swimming Speeds of Northern Pike (Esox lucius) in Lac Ste. Anne, Alberta
Authors: Diana James S.
Published: July 2010

Movements of six northern pike (Esox lucius) were monitored for 5 to 51 days by ultrasonic transmitters implanted surgically. The pike were inactive during 80% of the eight hundred and eighty-nine 5-min intervals monitored during summer and winter. No regular diel changes in activity were noted, except that pike were inactive at night. Swimming velocities calculated from gross displacements were maximum, 42 cm/s (0.91 body lengths (BL)/s); average, 23.1 cm/s (0.45 BL/s).Key words: movements, diel activity, seasonal activity, northern pike, Esox lucius; swimming speeds
DENSITY DEPENDENT STOCHASTIC NAVIER–STOKES EQUATIONS WITH NON-LIPSCHITZ RANDOM FORCING
Authors: SANGO MAMADOU
Published: July 2010

In this work, we investigate the question of existence of weak solutions to the density dependent stochastic Navier–Stokes equations. The noise considered contains functions which depend nonlinearly on the velocity and which do not satisfy the Lipschitz condition. Furthermore, the initial density is allowed to vanish. We introduce a suitable notion of probabilistic weak solution for the problem and prove its existence.
ALTERNATING SUM FORMULAE FOR THE DETERMINANT AND OTHER LINK INVARIANTS
Authors: DASBACH OLIVER T. , FUTER DAVID , KALFAGIANNI EFSTRATIA , LIN XIAO-SONG , STOLTZFUS NEAL W.
Published: July 2010

A classical result states that the determinant of an alternating link is equal to the number of spanning trees in a checkerboard graph of an alternating connected projection of the link. We generalize this result to show that the determinant is the alternating sum of the number of quasi-trees of genus j of the dessin of a non-alternating link.

Furthermore, we obtain formulas for coefficients of the Jones polynomial by counting quantities on dessins. In particular, we will show that the jth coefficient of the Jones polynomial is given by sub-dessins of genus less or equal to j.
HOW CAN WE RECOGNIZE POTENTIALLY ${\bf\Pi}^{0}_{\xi}$ SUBSETS OF THE PLANE?
Authors: LECOMTE DOMINIQUE
Published: July 2010

Let ξ ≥ 1 be a countable ordinal. We study the Borel subsets of the plane that can be made [Formula: see text] by refining the Polish topology on the real line. These sets are called potentially [Formula: see text]. We give a Hurewicz-like test to recognize potentially [Formula: see text] sets.
THORN-FORKING AS LOCAL FORKING
Authors: ADLER HANS
Published: July 2010

We introduce the notion of a preindependence relation between subsets of the big model of a complete first-order theory, an abstraction of the properties which numerous concrete notions such as forking, dividing, thorn-forking, thorn-dividing, splitting or finite satisfiability share in all complete theories. We examine the relation between four additional axioms (extension, local character, full existence and symmetry) that one expects of a good notion of independence.

We show that thorn-forking can be described in terms of local forking if we localize the number k in Kim's notion of "dividing with respect to k" (using Ben-Yaacov's "k-inconsistency witnesses") rather than the forking formulas. It follows that every theory with an M-symmetric lattice of algebraically closed sets (in Teq) is rosy, with a simple lattice theoretical interpretation of thorn-forking.
The Frankencamera
Authors: Adams Andrew , Talvala Eino-Ville , Park Sung Hee , Jacobs David E. , Ajdin Boris , Gelfand Natasha , Dolson Jennifer , Vaquero Daniel , Baek Jongmin , Tico Marius , Lensch Hendrik P. A. , Matusik Wojciech , Pulli Kari , Horowitz Mark , Levoy Marc
Published: July 2010

Although there has been much interest in computational photography within the research and photography communities, progress has been hampered by the lack of a portable, programmable camera with sufficient image quality and computing power. To address this problem, we have designed and implemented an open architecture and API for such cameras: the Frankencamera. It consists of a base hardware specification, a software stack based on Linux, and an API for C++. Our architecture permits control and synchronization of the sensor and image processing pipeline at the microsecond time scale, as well as the ability to incorporate and synchronize external hardware like lenses and flashes. This paper specifies our architecture and API, and it describes two reference implementations we have built. Using these implementations we demonstrate six computational photography applications: HDR viewfinding and capture, low-light viewfinding and capture, automated acquisition of extended dynamic range panoramas, foveal imaging, IMU-based hand shake detection, and rephotography. Our goal is to standardize the architecture and distribute Frankencameras to researchers and students, as a step towards creating a community of photographer-programmers who develop algorithms, applications, and hardware for computational cameras.
Diffusion coded photography for extended depth of field
Authors: Cossairt Oliver , Zhou Changyin , Nayar Shree
Published: July 2010

In recent years, several cameras have been introduced which extend depth of field (DOF) by producing a depth-invariant point spread function (PSF). These cameras extend DOF by deblurring a captured image with a single spatially-invariant PSF. For these cameras, the quality of recovered images depends both on the magnitude of the PSF spectrum (MTF) of the camera, and the similarity between PSFs at different depths. While researchers have compared the MTFs of different extended DOF cameras, relatively little attention has been paid to evaluating their depth invariances. In this paper, we compare the depth invariance of several cameras, and introduce a new camera that improves in this regard over existing designs, while still maintaining a good MTF.

Our technique utilizes a novel optical element placed in the pupil plane of an imaging system. Whereas previous approaches use optical elements characterized by their amplitude or phase profile, our approach utilizes one whose behavior is characterized by its scattering properties. Such an element is commonly referred to as an optical diffuser, and thus we refer to our new approach as
diffusion coding
. We show that diffusion coding can be analyzed in a simple and intuitive way by modeling the effect of a diffuser as a kernel in light field space. We provide detailed analysis of diffusion coded cameras and show results from an implementation using a custom designed diffuser.
Interactive on-surface signal deformation
Authors: Ritschel Tobias , Thormählen Thorsten , Dachsbacher Carsten , Kautz Jan , Seidel Hans-Peter
Published: July 2010

We present an interactive system for the artistic control of visual phenomena visible on surfaces. Our method allows the user to intuitively reposition shadows, caustics, and indirect illumination using a simple click-and-drag user interface working directly on surfaces. In contrast to previous approaches, the positions of the lights or objects in the scene remain unchanged, enabling localized edits of individual shading components. Our method facilitates the editing by computing a mapping from one surface location to another. Based on this mapping, we can not only edit shadows, caustics, and indirect illumination but also other surface properties, such as color or texture, in a unified way. This is achieved using an intuitive user-interface that allows the user to specify position constraints with drag-and-drop or sketching operations directly on the surface. Our approach requires no explicit surface parametrization and handles scenes with arbitrary topology. We demonstrate the applicability of the approach to interactive editing of shadows, reflections, refractions, textures, caustics, and diffuse indirect light. The effectiveness of the system to achieve an artistic goal is evaluated by a user study.
PantaRay
Authors: Pantaleoni Jacopo , Fascione Luca , Hill Martin , Aila Timo
Published: July 2010

We describe the architecture of a novel system for precomputing sparse directional occlusion caches. These caches are used for accelerating a fast cinematic lighting pipeline that works in the spherical harmonics domain. The system was used as a primary lighting technology in the movie Avatar, and is able to efficiently handle massive scenes of unprecedented complexity through the use of a flexible, stream-based geometry processing architecture, a novel out-of-core algorithm for creating efficient ray tracing acceleration structures, and a novel out-of-core GPU ray tracing algorithm for the computation of directional occlusion and spherical integrals at arbitrary points.
High resolution passive facial performance capture
Authors: Bradley Derek , Heidrich Wolfgang , Popa Tiberiu , Sheffer Alla
Published: July 2010

We introduce a purely passive facial capture approach that uses only an array of video cameras, but requires no template facial geometry, no special makeup or markers, and no active lighting. We obtain initial geometry using multi-view stereo, and then use a novel approach for automatically tracking texture detail across the frames. As a result, we obtain a high-resolution sequence of compatibly triangulated and parameterized meshes. The resulting sequence can be rendered with dynamically captured textures, while also consistently applying texture changes such as virtual makeup.
VideoMocap
Authors: Wei Xiaolin , Chai Jinxiang
Published: July 2010

This paper presents a video-based motion modeling technique for capturing physically realistic human motion from monocular video sequences. We formulate the video-based motion modeling process in an image-based keyframe animation framework. The system first computes camera parameters, human skeletal size, and a small number of 3D key poses from video and then uses 2D image measurements at intermediate frames to automatically calculate the "in between" poses. During reconstruction, we leverage Newtonian physics, contact constraints, and 2D image measurements to simultaneously reconstruct full-body poses, joint torques, and contact forces. We have demonstrated the power and effectiveness of our system by generating a wide variety of physically realistic human actions from uncalibrated monocular video sequences such as sports video footage.
K-set tilable surfaces
Authors: Fu Chi-Wing , Lai Chi-Fu , He Ying , Cohen-Or Daniel
Published: July 2010

This paper introduces a method for optimizing the tiles of a quad-mesh. Given a quad-based surface, the goal is to generate a set of
K
quads whose instances can produce a tiled surface that approximates the input surface. A solution to the problem is a K-set tilable surface, which can lead to an effective cost reduction in the physical construction of the given surface. Rather than molding lots of different building blocks, a K-set tilable surface requires the construction of
K
prefabricated components only. To realize the K-set tilable surface, we use a cluster-optimize approach. First, we iteratively cluster and analyze: clusters of similar shapes are merged, while edge connections between the
K
quads on the target surface are analyzed to learn the induced flexibility of the K-set tilable surface. Then, we apply a non-linear optimization model with constraints that maintain the
K
quads connections and shapes, and show how quad-based surfaces are optimized into K-set tilable surfaces. Our algorithm is demonstrated on various surfaces, including some that mimic the exteriors of certain renowned building landmarks.
A multiscale approach to mesh-based surface tension flows
Authors: Thürey Nils , Wojtan Chris , Gross Markus , Turk Greg
Published: July 2010

We present an approach to simulate flows driven by surface tension based on triangle meshes. Our method consists of two simulation layers: the first layer is an Eulerian method for simulating surface tension forces that is free from typical strict time step constraints. The second simulation layer is a Lagrangian finite element method that simulates sub-grid scale wave details on the fluid surface. The surface wave simulation employs an unconditionally stable, symplectic time integration method that allows for a high propagation speed due to strong surface tension. Our approach can naturally separate the grid- and sub-grid scales based on a volume-preserving mean curvature flow. As our model for the sub-grid dynamics enforces a local conservation of mass, it leads to realistic pinch off and merging effects. In addition to this method for simulating dynamic surface tension effects, we also present an efficient non-oscillatory approximation for capturing damped surface tension behavior. These approaches allow us to efficiently simulate complex phenomena associated with strong surface tension, such as Rayleigh-Plateau instabilities and crown splashes, in a short amount of time.
Physics-inspired topology changes for thin fluid features
Authors: Wojtan Chris , Thürey Nils , Gross Markus , Turk Greg
Published: July 2010

We propose a mesh-based surface tracking method for fluid animation that both preserves fine surface details and robustly adjusts the topology of the surface in the presence of arbitrarily thin features like sheets and strands. We replace traditional re-sampling methods with a convex hull method for connecting surface features during topological changes. This technique permits arbitrarily thin fluid features with minimal re-sampling errors by reusing points from the original surface. We further reduce re-sampling artifacts with a subdivision-based mesh-stitching algorithm, and we use a higher order interpolating subdivision scheme to determine the location of any newly-created vertices. The resulting algorithm efficiently produces detailed fluid surfaces with arbitrarily thin features while maintaining a consistent topology with the underlying fluid simulation.
Structure-based ASCII art
Authors: Xu Xuemiao , Zhang Linling , Wong Tien-Tsin
Published: July 2010

The wide availability and popularity of text-based communication channels encourage the usage of ASCII art in representing images. Existing tone-based ASCII art generation methods lead to halftone-like results and require high text resolution for display, as higher text resolution offers more tone variety. This paper presents a novel method to generate
structure-based
ASCII art that is currently mostly created by hand. It approximates the major line structure of the reference image content with the shape of characters. Representing the unlimited image content with the extremely limited shapes and restrictive placement of characters makes this problem challenging. Most existing shape similarity metrics either fail to address the misalignment in real-world scenarios, or are unable to account for the differences in position, orientation and scaling. Our key contribution is a novel
alignment-insensitive shape similarity (AISS) metric
that tolerates misalignment of shapes while accounting for the differences in position, orientation and scaling. Together with the constrained deformation approach, we formulate the ASCII art generation as an optimization that minimizes
shape dissimilarity
and
deformation
. Convincing results and user study are shown to demonstrate its effectiveness.
Line space gathering for single scattering in large scenes
Authors: Sun Xin , Zhou Kun , Lin Stephen , Guo Baining
Published: July 2010

We present an efficient technique to render single scattering in large scenes with reflective and refractive objects and homogeneous participating media. Efficiency is obtained by evaluating the final radiance along a viewing ray directly from the lighting rays passing near to it, and by rapidly identifying such lighting rays in the scene. To facilitate the search for nearby lighting rays, we convert lighting rays and viewing rays into 6D points and planes according to their Plücker coordinates and coefficients, respectively. In this 6D line space, the problem of closest lines search becomes one of closest points to a plane query, which we significantly accelerate using a spatial hierarchy of the 6D points. This approach to lighting ray gathering supports complex light paths with multiple reflections and refractions, and avoids the use of a volume representation, which is expensive for large-scale scenes. This method also utilizes far fewer lighting rays than the number of photons needed in traditional volumetric photon mapping, and does not discretize viewing rays into numerous steps for ray marching. With this approach, results similar to volumetric photon mapping are obtained efficiently in terms of both storage and computation.
Interactive hair rendering under environment lighting
Authors: Ren Zhong , Zhou Kun , Li Tengfei , Hua Wei , Guo Baining
Published: July 2010

We present an algorithm for interactive hair rendering with both single and multiple scattering effects under complex environment lighting. The outgoing radiance due to single scattering is determined by the integral of the product of the environment lighting, the scattering function, and the transmittance that accounts for self-shadowing among hair fibers. We approximate the environment light by a set of spherical radial basis functions (SRBFs) and thus convert the outgoing radiance integral into the sum of radiance contributions of all SRBF lights. For each SRBF light, we factor out the effective transmittance to represent the radiance integral as the product of two terms: the transmittance and the convolution of the SRBF light and the scattering function. Observing that the convolution term is independent of the hair geometry, we precompute it for commonly-used scattering models, and reduce the run-time computation to table lookups. We further propose a technique, called the
convolution optical depth map
, to efficiently approximate the effective transmittance by filtering the optical depth maps generated at the center of the SRBF using a depth-dependent kernel. As for the multiple scattering computation, we handle SRBF lights by using similar factorization and precomputation schemes, and adopt sparse sampling and interpolation to speed up the computation. Compared to off-line algorithms, our algorithm can generate images of comparable quality, but at interactive frame rates.
Illustrating how mechanical assemblies work
Authors: Mitra Niloy J. , Yang Yong-Liang , Yan Dong-Ming , Li Wilmot , Agrawala Maneesh
Published: July 2010

How things workvisualizations use a variety of visual techniques to depict the operation of complex mechanical assemblies. We present an automated approach for generating such visualizations. Starting with a 3D CAD model of an assembly, we first infer the motions of individual parts and the interactions between parts based on their geometry and a few user specified constraints. We then use this information to generate visualizations that incorporate motion arrows, frame sequences and animation to convey the causal chain of motions and mechanical interactions between parts. We present results for a wide variety of assemblies.
2.5D cartoon models
Authors: Rivers Alec , Igarashi Takeo , Durand Frédo
Published: July 2010

We present a way to bring cartoon objects and characters into the third dimension, by giving them the ability to rotate and be viewed from any angle. We show how 2D vector art drawings of a cartoon from different views can be used to generate a novel structure, the 2.5D cartoon model, which can be used to simulate 3D rotations and generate plausible renderings of the cartoon from any view. 2.5D cartoon models are easier to create than a full 3D model, and retain the 2D nature of hand-drawn vector art, supporting a wide range of stylizations that need not correspond to any real 3D shape.
Fabricating spatially-varying subsurface scattering
Authors: Dong Yue , Wang Jiaping , Pellacini Fabio , Tong Xin , Guo Baining
Published: July 2010

Many real world surfaces exhibit translucent appearance due to subsurface scattering. Although various methods exists to measure, edit and render subsurface scattering effects, no solution exists for manufacturing physical objects with desired translucent appearance. In this paper, we present a complete solution for fabricating a material volume with a desired surface BSSRDF. We stack layers from a fixed set of manufacturing materials whose thickness is varied spatially to reproduce the heterogeneity of the input BSSRDF. Given an input BSSRDF and the optical properties of the manufacturing materials, our system efficiently determines the optimal order and thickness of the layers. We demonstrate our approach by printing a variety of homogenous and heterogenous BSSRDFs using two hardware setups: a milling machine and a 3D printer.
Design and fabrication of materials with desired deformation behavior
Authors: Bickel Bernd , Bächer Moritz , Otaduy Miguel A. , Lee Hyunho Richard , Pfister Hanspeter , Gross Markus , Matusik Wojciech
Published: July 2010

This paper introduces a data-driven process for designing and fabricating materials with desired deformation behavior. Our process starts with measuring deformation properties of base materials. For each base material we acquire a set of example deformations, and we represent the material as a non-linear stress-strain relationship in a finite-element model. We have validated our material measurement process by comparing simulations of arbitrary stacks of base materials with measured deformations of fabricated material stacks. After material measurement, our process continues with designing stacked layers of base materials. We introduce an optimization process that finds the best combination of stacked layers that meets a user's criteria specified by example deformations. Our algorithm employs a number of strategies to prune poor solutions from the combinatorial search space. We demonstrate the complete process by designing and fabricating objects with complex heterogeneous materials using modern multi-material 3D printers.
OptiX
Authors: Parker Steven G. , Bigler James , Dietrich Andreas , Friedrich Heiko , Hoberock Jared , Luebke David , McAllister David , McGuire Morgan , Morley Keith , Robison Austin , Stich Martin
Published: July 2010

The NVIDIA® OptiX™ ray tracing engine is a programmable system designed for NVIDIA GPUs and other highly parallel architectures. The OptiX engine builds on the key observation that most ray tracing algorithms can be implemented using a small set of programmable operations. Consequently, the core of OptiX is a domain-specific just-in-time compiler that generates custom ray tracing kernels by combining user-supplied programs for ray generation, material shading, object intersection, and scene traversal. This enables the implementation of a highly diverse set of ray tracing-based algorithms and applications, including interactive rendering, offline rendering, collision detection systems, artificial intelligence queries, and scientific simulations such as sound propagation. OptiX achieves high performance through a compact object model and application of several ray tracing-specific compiler optimizations. For ease of use it exposes a single-ray programming model with full support for recursion and a dynamic dispatch mechanism similar to virtual function calls.
Rigid-body fracture sound with precomputed soundbanks
Authors: Zheng Changxi , James Doug L.
Published: July 2010

We propose a physically based algorithm for synthesizing sounds synchronized with brittle fracture animations. Motivated by laboratory experiments, we approximate brittle fracture sounds using time-varying rigid-body sound models. We extend methods for fracturing rigid materials by proposing a fast quasistatic stress solver to resolve near-audio-rate fracture events, energy-based fracture pattern modeling and estimation of "crack"-related fracture impulses. Multipole radiation models provide scalable sound radiation for complex debris and level of detail control. To reduce soundmodel generation costs for complex fracture debris, we propose Precomputed Rigid-Body Soundbanks comprised of precomputed ellipsoidal sound proxies. Examples and experiments are presented that demonstrate plausible and affordable brittle fracture sounds.
Robust physics-based locomotion using low-dimensional planning
Authors: Mordatch Igor , de Lasa Martin , Hertzmann Aaron
Published: July 2010

This paper presents a physics-based locomotion controller based on online planning. At each time-step, a planner optimizes locomotion over multiple phases of gait. Stance dynamics are modeled using a simplified Spring-Load Inverted (SLIP) model, while flight dynamics are modeled using projectile motion equations. Full-body control at each instant is optimized to match the instantaneous plan values, while also maintaining balance. Different types of gaits, including walking, running, and jumping, emerge automatically, as do transitions between different gaits. The controllers can traverse challenging terrain and withstand large external disturbances, while following high-level user commands at interactive rates.
Nonlinear disparity mapping for stereoscopic 3D
Authors: Lang Manuel , Hornung Alexander , Wang Oliver , Poulakos Steven , Smolic Aljoscha , Gross Markus
Published: July 2010

This paper addresses the problem of remapping the disparity range of stereoscopic images and video. Such operations are highly important for a variety of issues arising from the production, live broadcast, and consumption of 3D content. Our work is motivated by the observation that the displayed depth and the resulting 3D viewing experience are dictated by a complex combination of perceptual, technological, and artistic constraints. We first discuss the most important perceptual aspects of stereo vision and their implications for stereoscopic content creation. We then formalize these insights into a set of basic
disparity mapping operators.
These operators enable us to control and retarget the depth of a stereoscopic scene in a nonlinear and locally adaptive fashion. To implement our operators, we propose a new strategy based on
stereoscopic warping
of the input video streams. From a sparse set of stereo correspondences, our algorithm computes disparity and image-based saliency estimates, and uses them to compute a deformation of the input views so as to meet the target disparities. Our approach represents a practical solution for actual stereo production and display that does not require camera calibration, accurate dense depth maps, occlusion handling, or inpainting. We demonstrate the performance and versatility of our method using examples from live action post-production, 3D display size adaptation, and live broadcast. An additional user study and ground truth comparison further provide evidence for the quality and practical relevance of the presented work.
Controllable conformal maps for shape deformation and interpolation
Authors: Weber Ofir , Gotsman Craig
Published: July 2010

Conformal maps are considered very desirable for planar deformation applications, since they allow only local rotations and scale, avoiding shear and other visually disturbing distortions of local detail. Conformal maps are also orientation-preserving C
∞
diffeomorphisms, meaning they are extremely smooth and prevent unacceptable "foldovers" in the plane. Unfortunately, these maps are also notoriously difficult to control, so working with them in an interactive animation scenario to achieve specific effects is a significant challenge, sometimes even impossible.

We describe a novel 2D shape deformation system which generates conformal maps, yet provides the user a large degree of control over the result. For example, it allows discontinuities at user-specified boundary points, so true "bends" can be introduced into the deformation. It also allows the prescription of angular constraints at corners of the target image. Combining these provides for a very effective user experience. At the heart of our method is a very natural differential shape representation for conformal maps, using so-called "conformal factors" and "angular factors", which allow more intuitive control compared to representation in the usual spatial domain. Beyond deforming a given shape into a new one at each key frame, our method also provides the ability to interpolate between shapes in a very natural way, such that also the intermediate deformations are conformal.

Our method is extremely efficient: it requires only the solution of a small dense linear system at preprocess time and a matrix-vector multiplication during runtime (which can be implemented on a modern GPU), thus the deformations, even on extremely large images, may be performed in real-time.
Seeing is believing
Authors: Ennis Cathy , McDonnell Rachel , O'Sullivan Carol
Published: July 2010

In many scenes with human characters, interacting groups are an important factor for maintaining a sense of realism. However, little is known about what makes these characters appear realistic. In this paper, we investigate human sensitivity to audio mismatches (i.e., when individuals' voices are not matched to their gestures) and visual desynchronization (i.e., when the body motions of the individuals in a group are mis-aligned in time) in virtual human conversers. Using motion capture data from a range of both polite conversations and arguments, we conduct a series of perceptual experiments and determine some factors that contribute to the plausibility of virtual conversing groups. We found that participants are more sensitive to visual desynchronization of body motions, than to mismatches between the characters' gestures and their voices. Furthermore, synthetic conversations can appear sufficiently realistic once there is an appropriate balance between talker and listener roles. This is regardless of body motion desynchronization or mismatched audio.
Non-local scan consolidation for 3D urban scenes
Authors: Zheng Qian , Sharf Andrei , Wan Guowei , Li Yangyan , Mitra Niloy J. , Cohen-Or Daniel , Chen Baoquan
Published: July 2010

Recent advances in scanning technologies, in particular devices that extract depth through active sensing, allow fast scanning of urban scenes. Such rapid acquisition incurs imperfections: large regions remain missing, significant variation in sampling density is common, and the data is often corrupted with noise and outliers. However, buildings often exhibit large scale repetitions and self-similarities. Detecting, extracting, and utilizing such large scale repetitions provide powerful means to consolidate the imperfect data. Our key observation is that the same geometry, when scanned multiple times over reoccurrences of instances, allow application of a simple yet effective non-local filtering. The multiplicity of the geometry is fused together and projected to abase-geometrydefined by clustering corresponding surfaces. Denoising is applied by separating the process into off-plane and in-plane phases. We show that the consolidation of the reoccurrences provides robust denoising and allow reliable completion of missing parts. We present evaluation results of the algorithm on several LiDAR scans of buildings of varying complexity and styles.
Street slide
Authors: Kopf Johannes , Chen Billy , Szeliski Richard , Cohen Michael
Published: July 2010

Systems such as Google Street View and Bing Maps Streetside enable users to virtually visit cities by navigating between immersive 360° panoramas, or
bubbles.
The discrete moves from bubble to bubble enabled in these systems do not provide a good visual sense of a larger aggregate such as a whole city block. Multi-perspective "strip" panoramas can provide a visual summary of a city street but lack the full realism of immersive panoramas.

We present Street Slide, which combines the best aspects of the immersive nature of bubbles with the overview provided by multi-perspective strip panoramas. We demonstrate a seamless transition between bubbles and multi-perspective panoramas. We also present a dynamic construction of the panoramas which overcomes many of the limitations of previous systems. As the user slides sideways, the multi-perspective panorama is constructed and rendered dynamically to simulate either a perspective or
hyper-perspective
view. This provides a strong sense of parallax, which adds to the immersion. We call this form of sliding sideways while looking at a street façade a
street slide.
Finally we integrate annotations and a mini-map within the user interface to provide geographic information as well additional affordances for navigation. We demonstrate our Street Slide system on a series of intersecting streets in an urban setting. We report the results of a user study, which shows that visual searching is greatly enhanced with the Street Slide interface over existing systems from Google and Bing.
Acquisition and analysis of bispectral bidirectional reflectance and reradiation distribution functions
Authors: Hullin Matthias B. , Hanika Johannes , Ajdin Boris , Seidel Hans-Peter , Kautz Jan , Lensch Hendrik P. A.
Published: July 2010

In fluorescent materials, light from a certain band of incident wavelengths is reradiated at longer wavelengths, i.e., with a reduced per-photon energy. While fluorescent materials are common in everyday life, they have received little attention in computer graphics. Especially, no bidirectional reradiation measurements of fluorescent materials have been available so far. In this paper, we extend the well-known concept of the bidirectional reflectance distribution function (BRDF) to account for energy transfer between wavelengths, resulting in a
Bispectral Bidirectional Reflectance and Reradiation Distribution Function (bispectral BRRDF).
Using a bidirectional and bispectral measurement setup, we acquire reflectance and reradiation data of a variety of fluorescent materials, including vehicle paints, paper and fabric, and compare their renderings with RGB, RGBxRGB, and spectral BRDFs. Our acquisition is guided by a principal component analysis on complete bispectral data taken under a sparse set of angles. We show that in order to faithfully reproduce the full bispectral information for all other angles, only a very small number of wavelength pairs needs to be measured at a high angular resolution.
Manifold bootstrapping for SVBRDF capture
Authors: Dong Yue , Wang Jiaping , Tong Xin , Snyder John , Lan Yanxiang , Ben-Ezra Moshe , Guo Baining
Published: July 2010

Manifold bootstrapping is a new method for data-driven modeling of real-world, spatially-varying reflectance, based on the idea that reflectance over a given material sample forms a low-dimensional manifold. It provides a high-resolution result in both the spatial and angular domains by decomposing reflectance measurement into two lower-dimensional phases. The first acquires
representatives
of high angular dimension but sampled sparsely over the surface, while the second acquires
keys
of low angular dimension but sampled densely over the surface.

We develop a hand-held, high-speed BRDF capturing device for phase one measurements. A condenser-based optical setup collects a dense hemisphere of rays emanating from a single point on the target sample as it is manually scanned over it, yielding 10 BRDF point measurements per second. Lighting directions from 6 LEDs are applied at each measurement; these are amplified to a full 4D BRDF using the general (NDF-tabulated) microfacet model. The second phase captures
N
=20-200 images of the entire sample from a fixed view and lit by a varying area source. We show that the resulting
N
-dimensional keys capture much of the distance information in the original BRDF space, so that they effectively discriminate among representatives, though they lack sufficient angular detail to reconstruct the SVBRDF by themselves. At each surface position, a local linear combination of a small number of neighboring representatives is computed to match each key, yielding a high-resolution SVBRDF. A quick capture session (10-20 minutes) on simple devices yields results showing sharp and anisotropic specularity and rich spatial detail.
Discrete scale axis representations for 3D geometry
Authors: Miklos Balint , Giesen Joachim , Pauly Mark
Published: July 2010

This paper addresses the fundamental problem of computing stable medial representations of 3D shapes. We propose a
spatially adaptive
classification of geometric features that yields a robust algorithm for generating medial representations at different levels of abstraction. The recently introduced continuous scale axis transform serves as the mathematical foundation of our algorithm. We show how geometric and topological properties of the continuous setting carry over to discrete shape representations. Our method combines scaling operations of medial balls for geometric simplification with filtrations of the medial axis and provably good conversion steps to and from union of balls, to enable efficient processing of a wide variety shape representations including polygon meshes, 3D images, implicit surfaces, and point clouds. We demonstrate the robustness and versatility of our algorithm with an extensive validation on hundreds of shapes including complex geometries consisting of millions of triangles.
Learning 3D mesh segmentation and labeling
Authors: Kalogerakis Evangelos , Hertzmann Aaron , Singh Karan
Published: July 2010

This paper presents a data-driven approach to simultaneous segmentation and labeling of parts in 3D meshes. An objective function is formulated as a Conditional Random Field model, with terms assessing the consistency of faces with labels, and terms between labels of neighboring faces. The objective function is learned from a collection of labeled training meshes. The algorithm uses hundreds of geometric and contextual label features and learns different types of segmentations for different tasks, without requiring manual parameter tuning. Our algorithm achieves a significant improvement in results over the state-of-the-art when evaluated on the Princeton Segmentation Benchmark, often producing segmentations and labelings comparable to those produced by humans.
Apparent layer operations for the manipulation of deformable objects
Authors: Igarashi Takeo , Mitani Jun
Published: July 2010

We introduce layer operations for single-view 3D deformable object manipulation, in which the user can control the depth order of layered 3D objects resting on a flat ground with simple clicks and drags, as in 2D drawing systems. We present two interaction techniques based on this idea and describe their implementation. The first technique is explicit layer swap. The user clicks the target layer, and the system swaps the layer with the one directly underneath it. The second technique is layer-aware dragging. As the user drags the object, the system adjusts its depth automatically to pass over or under a colliding object in the screen space, according to user control. Although the user interface is 2.5D, all scene representations are true 3D, and thus the system naturally supports local layering, self-occlusions, and folds. Internally, the system dynamically computes the apparent layer structure in the current configuration and makes appropriate depth adjustments to obtain the desired results. We demonstrate the effectiveness of this approach in cloth and rope manipulation systems.
A novel algorithm for incompressible flow using only a coarse grid projection
Authors: Lentine Michael , Zheng Wen , Fedkiw Ronald
Published: July 2010

Large scale fluid simulation can be difficult using existing techniques due to the high computational cost of using large grids. We present a novel technique for simulating detailed fluids quickly. Our technique coarsens the Eulerian fluid grid during the pressure solve, allowing for a fast implicit update but still maintaining the resolution obtained with a large grid. This allows our simulations to run at a fraction of the cost of existing techniques while still providing the fine scale structure and details obtained with a full projection. Our algorithm scales well to very large grids and large numbers of processors, allowing for high fidelity simulations that would otherwise be intractable.
Learning behavior styles with inverse reinforcement learning
Authors: Lee Seong Jae , Popović Zoran
Published: July 2010

We present a method for inferring the behavior styles of character controllers from a small set of examples. We show that a rich set of behavior variations can be captured by determining the appropriate reward function in the reinforcement learning framework, and show that the discovered reward function can be applied to different environments and scenarios. We also introduce a new algorithm to recover the unknown reward function that improves over the original apprenticeship learning algorithm. We show that the reward function representing a behavior style can be applied to a variety of different tasks, while still preserving the key features of the style present in the given examples. We describe an adaptive process where an author can, with just a few additional examples, refine the behavior so that it has better generalization properties.
Gesture controllers
Authors: Levine Sergey , Krähenbühl Philipp , Thrun Sebastian , Koltun Vladlen
Published: July 2010

We introduce
gesture controllers
, a method for animating the body language of avatars engaged in live spoken conversation. A gesture controller is an optimal-policy controller that schedules gesture animations in real time based on acoustic features in the user's speech. The controller consists of an inference layer, which infers a distribution over a set of hidden states from the speech signal, and a control layer, which selects the optimal motion based on the inferred state distribution. The inference layer, consisting of a specialized conditional random field, learns the hidden structure in body language style and associates it with acoustic features in speech. The control layer uses reinforcement learning to construct an optimal policy for selecting motion clips from a distribution over the learned hidden states. The modularity of the proposed method allows customization of a character's gesture repertoire, animation of non-human characters, and the use of additional inputs such as speech recognition or direct user control.
Parametric reshaping of human bodies in images
Authors: Zhou Shizhe , Fu Hongbo , Liu Ligang , Cohen-Or Daniel , Han Xiaoguang
Published: July 2010

We present an easy-to-use image retouching technique for realistic reshaping of human bodies in a single image. A
model-based
approach is taken by integrating a 3D whole-body morphable model into the reshaping process to achieve globally consistent editing effects. A novel
body-aware image warping
approach is introduced to reliably transfer the reshaping effects from the model to the image, even under moderate fitting errors. Thanks to the parametric nature of the model, our technique parameterizes the degree of reshaping by a small set of semantic attributes, such as weight and height. It allows easy creation of desired reshaping effects by changing the full-body attributes, while producing visually pleasing results even for loosely-dressed humans in casual photographs with a variety of poses and shapes.
Image warps for artistic perspective manipulation
Authors: Carroll Robert , Agarwala Aseem , Agrawala Maneesh
Published: July 2010

Painters and illustrators commonly sketch vanishing points and lines to guide the construction of perspective images. We present a tool that gives users the ability to manipulate perspective in photographs using image space controls similar to those used by artists. Our approach computes a 2D warp guided by constraints based on projective geometry. A user annotates an image by marking a number of image space constraints including planar regions of the scene, straight lines, and associated vanishing points. The user can then use the lines, vanishing points, and other point constraints as handles to control the warp. Our system optimizes the warp such that straight lines remain straight, planar regions transform according to a homography, and the entire mapping is as shape-preserving as possible. While the result of this warp is not necessarily an accurate perspective projection of the scene, it is often visually plausible. We demonstrate how this approach can be used to produce a variety of effects, such as changing the perspective composition of a scene, exploring artistic perspectives not realizable with a camera, and matching perspectives of objects from different images so that they appear consistent for compositing.