bluuebunny/crossref_metadata_2025 huggingface dataset:
Regional geochemical patterns in SE Scotland: source lithology, inheritance and glacial overprinting
Authors: Stone P. , McMillan A. A.
Published: July 2013

Synopsis

The Lower Palaeozoic Southern Uplands terrane shows a NE–SW, strike-parallel coincidence of regional geochemical lineaments defined from stream-sediment data, and major lithostratigraphically significant structures. West of Moffat, Silurian strata of the Gala and Hawick groups are divided by geochemical lineaments coincident with the Laurieston Fault. East of Moffat, the geochemical lineaments diverge towards the NE with Gala-type regional geochemistry (high Sr and Ba, low CaO) to the north of the Moffat Valley Fault, whilst Hawick-type regional geochemistry (low Sr and Ba, high CaO) continues to the south of the Laurieston Fault; between the faults lies the recently-defined Ettrick Group. Beyond the eastern end of the Lower Palaeozoic outcrop, its geochemical lineaments extend across the unconformable cover of Devonian ‘Old Red Sandstone’. This is partly a drainage catchment effect, but two other possible explanations are considered: a localized derivation of the Devonian clastic rocks, such that they inherit the compositional patterns of the underlying Lower Palaeozoic sandstones; or a geochemical signature imposed by glacial deposits derived from the Lower Palaeozoic outcrop. The local effect of glacial dispersion is confirmed by the distribution of TiO
2
; anomalously high levels associated with Carboniferous mafic lavas have been transported NE across the low-TiO
2
Carboniferous sedimentary rocks of the Tweed Basin.
The mineral prospecting expeditions to the South Atlantic islands and Antarctic Peninsula region made by the Scottish geologist David Ferguson, 1912–1914
Authors: Stone P. , Faithfull J.
Published: July 2013

Synopsis

David Ferguson’s mineral prospecting expeditions to South Georgia (1912), the Falkland Islands and the South Shetland Islands (1913–1914), on behalf of the Christian Salvesen whaling company of Leith and now largely forgotten, were early examples of commercially motivated terrestrial exploration in the South Atlantic region. Prior geological knowledge was very limited and Ferguson complemented his unsuccessful prospecting work with attempts to understand the regional geology of the areas that he visited. These interpretations were based on relatively cursory fieldwork undertaken in an arduous environment, and did not prove robust; but the well-documented specimen collections that Ferguson accumulated provided the basis for excellent and much-cited petrographical accounts by G. W. Tyrrell of Glasgow University. Ferguson had studied geology at the university and the influence of his mentor there, Professor J. W. Gregory, is apparent. In turn, Gregory utilized Ferguson’s observations in support of a subsided ‘South Atlantic continent’, opposing the ‘displacement hypothesis’ for that region formalized by Alfred Wegener from 1912 onwards. Ferguson’s field notebooks and most of his rock specimens are now held by Glasgow University (Archive Services and Hunterian Museum, respectively) but he distributed representative specimen collections widely, and these are extant in several other British museums. Specimens were also supplied to, and discussed with, William Speirs Bruce who, following the 1902–1904 Scottish National Antarctic Expedition, took a keen interest in Ferguson’s discoveries.
Detrital monazite geochronology, Upper Jurassic–Lower Cretaceous of the Scotian Basin: significance for tracking first-cycle sources
Authors: Pe-Piper Georgia , Piper David J. W. , Triantafyllidis S.
Published: July 2013

Monazite geochronology was applied to an east–west transect of latest Jurassic and Lower Cretaceous deltaic sandstones of the Scotian Basin, to assess sediment sources and dispersal pathways. More than 200 detrital monazite grains yielded 694 electron microprobe age determinations with 1σ errors <±20%. Based on age, external morphology, zoning, inclusions and major element chemistry (rare earth element [REE], Th, Y), monazite grains represent more than 20 discrete sources. Similar proportions of euhedral and subhedral compared with irregular and rounded monazite grains in most age classes, together with comparison with detrital muscovite and zircon geochronology, suggest that most monazite is first cycle. Six types of REE distribution are recognized (A–F). Many igneous monazites show chemical zoning, contain sparse euhedral inclusions, and have REE distributions of types A and E. Many metamorphic monazites contain inclusions, commonly aligned, are generally rounded–subhedral to rounded, and have REE distributions of types B, C and D. Monazite geochronology shows important supply to the Scotian Basin from the Labrador rift shoulder as early as Tithonian; from Avalonian sources in the Tithonian; from Ordovician sources in northern New Brunswick, apparently via the Chaswood River; and from the inner continental shelf, particularly in the Hauterivian–Barremian.
Tying catchment to basin in a giant sediment routing system: a source-to-sink study of the Neogene–Recent Amur River and its delta in the North Sakhalin Basin
Authors: Nicholson Uisdean , Poynter Sarah , Clift Peter D. , Macdonald David I. M.
Published: July 2013

This paper uses an extensive dataset from more than 200 samples to provide a comprehensive source-to-sink analysis of the Amur River and its delta in the Russian Far East. The majority of sand-sized sediment in the Amur River and its former delta comes from upstream of the Lesser Khingan Ridge, shown by uniformity of sediment composition in the lower 1700 km of the river. Stable mineral ratios, U–Pb age spectra and garnet geochemistry show little stratigraphic provenance-specific variation in the Neogene delta. This renders Miocene–Pliocene drainage capture models unlikely.

The onset of uplift in the delta is marked by a decrease in the apatite–tourmaline index (ATi) in Upper Pliocene offshore well samples, caused by dissolution of apatite as sediments were uplifted and eroded onshore Sakhalin. These wells also show variable ATi and garnet–zircon index (GZi) values in Lower Miocene samples, which could potentially be used for stratigraphic correlation.

A positive correlation between GZi values and distance from the river mouth is attributed to hydrodynamic sorting across the delta system. This has negative implications for the use of this stable mineral index and others of a similar hydraulic equivalence as regional correlation tools on a basin scale (>100 km).

Supplementary material:

Heavy mineral data, petrographic data, geochronometric data, sample locations available at
www.geolsoc.org.uk/SUP18643
.
Robust inside-outside segmentation using generalized winding numbers
Authors: Jacobson Alec , Kavan Ladislav , Sorkine-Hornung Olga
Published: July 2013

Solid shapes in computer graphics are often represented with boundary descriptions, e.g. triangle meshes, but animation, physically-based simulation, and geometry processing are more realistic and accurate when explicit volume representations are available. Tetrahedral meshes which exactly contain (interpolate) the input boundary description are desirable but difficult to construct for a large class of input meshes. Character meshes and CAD models are often composed of many connected components with numerous self-intersections, non-manifold pieces, and open boundaries, precluding existing meshing algorithms. We propose an automatic algorithm handling all of these issues, resulting in a compact discretization of the input's inner volume. We only require reasonably consistent orientation of the input triangle mesh. By generalizing the winding number for arbitrary triangle meshes, we define a function that is a perfect segmentation for watertight input and is well-behaved otherwise. This function guides a graphcut segmentation of a constrained Delaunay tessellation (CDT), providing a minimal description that meets the boundary exactly and may be fed as input to existing tools to achieve element quality. We highlight our robustness on a number of examples and show applications of solving PDEs, volumetric texturing and elastic simulation.
Cubic mean value coordinates
Authors: Li Xian-Ying , Ju Tao , Hu Shi-Min
Published: July 2013

We present a new method for interpolating both boundary values and gradients over a 2D polygonal domain. Despite various previous efforts, it remains challenging to define a closed-form interpolant that produces natural-looking functions while allowing flexible control of boundary constraints. Our method builds on an existing transfinite interpolant over a continuous domain, which in turn extends the classical mean value interpolant. We re-derive the interpolant from the mean value property of biharmonic functions, and prove that the interpolant indeed matches the gradient constraints when the boundary is piece-wise linear. We then give closed-form formula (as generalized barycentric coordinates) for boundary constraints represented as polynomials up to degree 3 (for values) and 1 (for normal derivatives) over each polygon edge. We demonstrate the flexibility and efficiency of our coordinates in two novel applications, smooth image deformation using curved cage networks and adaptive simplification of gradient meshes.
A two-continua approach to Eulerian simulation of water spray
Authors: Nielsen Michael B. , Østerby Ole
Published: July 2013

Physics based simulation of the dynamics of water spray - water droplets dispersed in air - is a means to increase the visual plausibility of computer graphics modeled phenomena such as waterfalls, water jets and stormy seas. Spray phenomena are frequently encountered by the visual effects industry and often challenge state of the art methods. Current spray simulation pipelines typically employ a combination of Lagrangian (particle) and Eulerian (volumetric) methods - the Eulerian methods being used for parts of the spray where individual droplets are not apparent. However, existing Eulerian methods in computer graphics are based on gas solvers that will for example exhibit hydrostatic equilibrium in certain scenarios where the air is expected to rise and the water droplets fall. To overcome this problem, we propose to simulate spray in the Eulerian domain as a two-way coupled two-continua of air and water phases co-existing at each point in space. The fundamental equations originate in applied physics and we present a number of contributions that make Eulerian two-continua spray simulation feasible for computer graphics applications. The contributions include a Poisson equation that fits into the operator splitting methodology as well as (semi-)implicit discretizations of droplet diffusion and the drag force with improved stability properties. As shown by several examples, our approach allows us to more faithfully capture the dynamics of spray than previous Eulerian methods.
Adaptive fracture simulation of multi-layered thin plates
Authors: Busaryev Oleksiy , Dey Tamal K. , Wang Huamin
Published: July 2013

The fractures of thin plates often exhibit complex physical behaviors in the real world. In particular, fractures caused by tearing are different from fractures caused by in-plane motions. In this paper, we study how to make thin-plate fracture animations more realistic from three perspectives. We propose a stress relaxation method, which is applied to avoid shattering artifacts after generating each fracture cut. We formulate a fracture-aware remeshing scheme based on constrained Delaunay triangulation, to adaptively provide more fracture details. Finally, we use our multi-layered model to simulate complex fracture behaviors across thin layers. Our experiment shows that the system can efficiently and realistically simulate the fractures of multi-layered thin plates.
Dynamic element textures
Authors: Ma Chongyang , Wei Li-Yi , Lefebvre Sylvain , Tong Xin
Published: July 2013

Many natural phenomena consist of geometric elements with dynamic motions characterized by small scale repetitions over large scale structures, such as particles, herds, threads, and sheets. Due to their ubiquity, controlling the appearance and behavior of such phenomena is important for a variety of graphics applications. However, such control is often challenging; the repetitive elements are often too numerous for manual edit, while their overall structures are often too versatile for fully automatic computation.

We propose a method that facilitates easy and intuitive controls at both scales: high-level structures through spatial-temporal output constraints (e.g. overall shape and motion of the output domain), and low-level details through small input exemplars (e.g. element arrangements and movements). These controls are suitable for manual specification, while the corresponding geometric and dynamic repetitions are suitable for automatic computation. Our system takes such user controls as inputs, and generates as outputs the corresponding repetitions satisfying the controls.

Our method, which we call
dynamic element textures
, aims to produce such controllable repetitions through a combination of constrained optimization (satisfying controls) and data driven computation (synthesizing details). We use spatial-temporal samples as the core representation for dynamic geometric elements. We propose analysis algorithms for decomposing small scale repetitions from large scale themes, as well as synthesis algorithms for generating outputs satisfying user controls. Our method is general, producing a range of artistic effects that previously required disparate and specialized techniques.
Computing self-supporting surfaces by regular triangulation
Authors: Liu Yang , Pan Hao , Snyder John , Wang Wenping , Guo Baining
Published: July 2013

Masonry structures must be compressively self-supporting; designing such surfaces forms an important topic in architecture as well as a challenging problem in geometric modeling. Under certain conditions, a surjective mapping exists between a
power diagram
, defined by a set of 2D vertices and associated weights, and the reciprocal diagram that characterizes the force diagram of a discrete self-supporting network. This observation lets us define a new and convenient parameterization for the space of self-supporting networks. Based on it and the discrete geometry of this design space, we present novel geometry processing methods including surface smoothing and remeshing which significantly reduce the magnitude of force densities and homogenize their distribution.
Stylizing animation by example
Authors: Bénard Pierre , Cole Forrester , Kass Michael , Mordatch Igor , Hegarty James , Senn Martin Sebastian , Fleischer Kurt , Pesare Davide , Breeden Katherine
Published: July 2013

Skilled artists, using traditional media or modern computer painting tools, can create a variety of expressive styles that are very appealing in still images, but have been unsuitable for animation. The key difficulty is that existing techniques lack adequate temporal coherence to animate these styles effectively. Here we augment the range of practical animation styles by extending the guided texture synthesis method of
Image Analogies
[Hertzmann et al. 2001] to create temporally coherent animation sequences. To make the method art directable, we allow artists to paint portions of keyframes that are used as constraints. The in-betweens calculated by our method maintain stylistic continuity and yet change no more than necessary over time.
Opacity optimization for 3D line fields
Authors: Günther Tobias , Rössl Christian , Theisel Holger
Published: July 2013

For the visualization of dense line fields, the careful selection of lines to be rendered is a vital aspect. In this paper, we present a global line selection approach that is based on an optimization process. Starting with an initial set of lines that covers the domain, all lines are rendered with a varying opacity, which is subject to the minimization of a bounded-variable least-squares problem. The optimization strives to keep a balance between information presentation and occlusion avoidance. This way, we obtain view-dependent opacities of the line segments, allowing a real-time free navigation while minimizing the danger of missing important structures in the visualization. We compare our technique with existing local and greedy approaches and apply it to data sets in flow visualization, medical imaging, physics, and computer graphics.
Learning part-based templates from large collections of 3D shapes
Authors: Kim Vladimir G. , Li Wilmot , Mitra Niloy J. , Chaudhuri Siddhartha , DiVerdi Stephen , Funkhouser Thomas
Published: July 2013

As large repositories of 3D shape collections continue to grow, understanding the data, especially encoding the inter-model similarity and their variations, is of central importance. For example, many data-driven approaches now rely on access to semantic segmentation information, accurate inter-model point-to-point correspondence, and deformation models that characterize the model collections. Existing approaches, however, are either supervised requiring manual labeling; or employ super-linear matching algorithms and thus are unsuited for analyzing large collections spanning many thousands of models. We propose an automatic algorithm that starts with an initial template model and then jointly optimizes for part segmentation, point-to-point surface correspondence, and a compact deformation model to best explain the input model collection. As output, the algorithm produces a set of probabilistic part-based templates that groups the original models into clusters of models capturing their styles and variations. We evaluate our algorithm on several standard datasets and demonstrate its scalability by analyzing much larger collections of up to thousands of shapes.
Real time dynamic fracture with volumetric approximate convex decompositions
Authors: Müller Matthias , Chentanez Nuttapong , Kim Tae-Yong
Published: July 2013

We propose a new fast, robust and controllable method to simulate the dynamic destruction of large and complex objects in real time. The common method for fracture simulation in computer games is to pre-fracture models and replace objects by their pre-computed parts at run-time. This popular method is computationally cheap but has the disadvantages that the fracture pattern does not align with the impact location and that the number of hierarchical fracture levels is fixed. Our method allows dynamic fracturing of large objects into an unlimited number of pieces fast enough to be used in computer games. We represent visual meshes by volumetric approximate convex decompositions (VACD) and apply user-defined fracture patterns dependent on the impact location. The method supports partial fracturing meaning that fracture patterns can be applied locally at multiple locations of an object. We propose new methods for computing a VACD, for approximate convex hull construction and for detecting islands in the convex decomposition after partial destruction in order to determine support structures.
Weighted averages on surfaces
Authors: Panozzo Daniele , Baran Ilya , Diamanti Olga , Sorkine-Hornung Olga
Published: July 2013

We consider the problem of generalizing affine combinations in Euclidean spaces to triangle meshes: computing weighted averages of points on surfaces. We address both the
forward problem
, namely computing an average of given anchor points on the mesh with given weights, and the
inverse problem
, which is computing the weights given anchor points and a target point. Solving the forward problem on a mesh enables applications such as splines on surfaces, Laplacian smoothing and remeshing. Combining the forward and inverse problems allows us to define a correspondence mapping between two different meshes based on provided corresponding point pairs, enabling texture transfer, compatible remeshing, morphing and more. Our algorithm solves a single instance of a forward or an inverse problem in a few microseconds. We demonstrate that anchor points in the above applications can be added/removed and moved around on the meshes at interactive framerates, giving the user an immediate result as feedback.
Scalable real-time volumetric surface reconstruction
Authors: Chen Jiawen , Bautembach Dennis , Izadi Shahram
Published: July 2013

We address the fundamental challenge of
scalability
for real-time volumetric surface reconstruction methods. We design a memory efficient, hierarchical data structure for commodity graphics hardware, which supports live reconstruction of large-scale scenes with fine geometric details. Our sparse data structure fuses overlapping depth maps from a moving depth camera into a single volumetric representation, from which detailed surface models are extracted. Our hierarchy losslessly streams data bidirectionally between GPU and host, allowing for unbounded reconstructions. Our pipeline, comprised of depth map post-processing, camera pose estimation, volumetric fusion, surface extraction, and streaming, runs entirely in real-time. We experimentally demonstrate that a shallow hierarchy with relatively large branching factors yields the best memory/speed tradeoff, consuming an order of magnitude less memory than a regular grid. We compare an implementation of our data structure to existing methods and demonstrate higher-quality reconstructions on a variety of large-scale scenes, all captured in real-time.
Modeling friction and air effects between cloth and deformable bodies
Authors: Chen Zhili , Feng Renguo , Wang Huamin
Published: July 2013

Real-world cloth exhibits complex behaviors when it contacts deformable bodies. In this paper, we study how to improve the simulation of cloth-body interactions from three perspectives: collision, friction, and air pressure. We propose an efficient and robust algorithm to detect the collisions between cloth and deformable bodies, using the surface traversal technique. We develop a friction measurement device and we use it to capture frictional data from real-world experiments. The derived friction model can realistically handle complex friction properties of cloth, including anisotropy and nonlinearity. To produce pressure effects caused by the air between cloth and deformable bodies, we define an air mass field on the cloth layer and we use real-world air permeability data to animate it over time. Our results demonstrate the efficiency and accuracy of our system in simulating objects with a three-layer structure (i.e., a cloth layer, an air layer, and an inner body layer), such as pillows, comforters, down jackets, and stuffed toys.
Acquiring reflectance and shape from continuous spherical harmonic illumination
Authors: Tunwattanapong Borom , Fyffe Graham , Graham Paul , Busch Jay , Yu Xueming , Ghosh Abhijeet , Debevec Paul
Published: July 2013

We present a novel technique for acquiring the geometry and spatially-varying reflectance properties of 3D objects by observing them under continuous spherical harmonic illumination conditions. The technique is general enough to characterize either entirely specular or entirely diffuse materials, or any varying combination across the surface of the object. We employ a novel computational illumination setup consisting of a rotating arc of controllable LEDs which sweep out programmable spheres of incident illumination during 1-second exposures. We illuminate the object with a succession of spherical harmonic illumination conditions, as well as photographed environmental lighting for validation. From the response of the object to the harmonics, we can separate diffuse and specular reflections, estimate world-space diffuse and specular normals, and compute anisotropic roughness parameters for each view of the object. We then use the maps of both diffuse and specular reflectance to form correspondences in a multiview stereo algorithm, which allows even highly specular surfaces to be corresponded across views. The algorithm yields a complete 3D model and a set of merged reflectance maps. We use this technique to digitize the shape and reflectance of a variety of objects difficult to acquire with other techniques and present validation renderings which match well to photographs in similar lighting.
Low-budget transient imaging using photonic mixer devices
Authors: Heide Felix , Hullin Matthias B. , Gregson James , Heidrich Wolfgang
Published: July 2013

Transient imaging is an exciting a new imaging modality that can be used to understand light propagation in complex environments, and to capture and analyze scene properties such as the shape of hidden objects or the reflectance properties of surfaces.

Unfortunately, research in transient imaging has so far been hindered by the high cost of the required instrumentation, as well as the fragility and difficulty to operate and calibrate devices such as femtosecond lasers and streak cameras.

In this paper, we explore the use of photonic mixer devices (PMD), commonly used in inexpensive time-of-flight cameras, as alternative instrumentation for transient imaging. We obtain a sequence of differently modulated images with a PMD sensor, impose a model for local light/object interaction, and use an optimization procedure to infer transient images given the measurements and model. The resulting method produces transient images at a cost several orders of magnitude below existing methods, while simultaneously simplifying and speeding up the capture process.
Automated video looping with progressive dynamism
Authors: Liao Zicheng , Joshi Neel , Hoppe Hugues
Published: July 2013

Given a short video we create a representation that captures a spectrum of looping videos with varying levels of dynamism, ranging from a static image to a highly animated loop. In such a progressively dynamic video, scene liveliness can be adjusted interactively using a slider control. Applications include background images and slideshows, where the desired level of activity may depend on personal taste or mood. The representation also provides a segmentation of the scene into independently looping regions, enabling interactive local adjustment over dynamism. For a landscape scene, this control might correspond to selective animation and deanimation of grass motion, water ripples, and swaying trees. Converting arbitrary video to looping content is a challenging research problem. Unlike prior work, we explore an optimization in which each pixel automatically determines its own looping period. The resulting nested segmentation of static and dynamic scene regions forms an extremely compact representation.
Computational design of mechanical characters
Authors: Coros Stelian , Thomaszewski Bernhard , Noris Gioacchino , Sueda Shinjiro , Forberg Moira , Sumner Robert W. , Matusik Wojciech , Bickel Bernd
Published: July 2013

We present an interactive design system that allows non-expert users to create animated mechanical characters. Given an articulated character as input, the user iteratively creates an animation by sketching motion curves indicating how different parts of the character should move. For each motion curve, our framework creates an optimized mechanism that reproduces it as closely as possible. The resulting mechanisms are attached to the character and then connected to each other using gear trains, which are created in a semi-automated fashion. The mechanical assemblies generated with our system can be driven with a single input driver, such as a hand-operated crank or an electric motor, and they can be fabricated using rapid prototyping devices. We demonstrate the versatility of our approach by designing a wide range of mechanical characters, several of which we manufactured using 3D printing. While our pipeline is designed for characters driven by planar mechanisms, significant parts of it extend directly to non-planar mechanisms, allowing us to create characters with compelling 3D motions.
Painting by feature
Authors: Lukáč Michal , Fišer Jakub , Bazin Jean-Charles , Jamriška Ondřej , Sorkine-Hornung Alexander , Sýkora Daniel
Published: July 2013

In this paper we propose a reinterpretation of the
brush
and the
fill
tools for digital image painting. The core idea is to provide an intuitive approach that allows users to paint in the visual style of arbitrary example images. Rather than a static library of colors, brushes, or fill patterns, we offer users entire images as their palette, from which they can select arbitrary contours or textures as their brush or fill tool in their own creations. Compared to previous example-based techniques related to the painting-by-numbers paradigm we propose a new strategy where users can generate salient texture boundaries by our randomized graph-traversal algorithm and apply a content-aware fill to transfer textures into the delimited regions. This workflow allows users of our system to intuitively create visually appealing images that better preserve the visual richness and fluidity of arbitrary example images. We demonstrate the potential of our approach in various applications including interactive image creation, editing and vector image stylization.
Interactive authoring of simulation-ready plants
Authors: Zhao Yili , Barbič Jernej
Published: July 2013

Physically based simulation can produce quality motion of plants, but requires an authoring stage to convert plant "polygon soup" triangle meshes to a format suitable for physically based simulation. We give a system that can author complex simulation-ready plants in a manner of minutes. Our system decomposes the plant geometry, establishes a hierarchy, builds and connects simulation meshes, and detects instances. It scales to anatomically realistic geometry of adult plants, is robust to non-manifold input geometry, gaps between branches or leaves, free-flying leaves not connected to any branch, spurious geometry, and plant self-collisions in the input configuration. We demonstrate the results using a FEM model reduction simulator that can compute large-deformation dynamics of complex plants at interactive rates, subject to user forces, gravity or randomized wind. We also provide plant fracture (with pre-specified patterns), inverse kinematics to easily pose plants, as well as interactive design of plant material properties. We authored and simulated over 100 plants from diverse climates and geographic regions, including broadleaf (deciduous) trees and conifers, bushes and flowers. Our largest simulations involve anatomically realistic adult trees with hundreds of branches and over 100,000 leaves.
Super space clothoids
Authors: Casati Romain , Bertails-Descoubes Florence
Published: July 2013

Thin elastic filaments in real world such as vine tendrils, hair ringlets or curled ribbons often depict a very smooth, curved shape that low-order rod models --- e.g., segment-based rods --- fail to reproduce accurately and compactly. In this paper, we push forward the investigation of high-order models for thin, inextensible elastic rods by building the dynamics of a
G
2
-continuous piecewise 3D clothoid: a smooth space curve with piecewise affine curvature. With the aim of precisely integrating the rod kinematic problem, for which no closed-form solution exists, we introduce a dedicated integration scheme based on power series expansions. It turns out that our algorithm reaches machine precision orders of magnitude faster compared to classical numerical integrators. This property, nicely preserved under simple algebraic and differential operations, allows us to compute all spatial terms of the rod kinematics and dynamics in both an efficient and accurate way. Combined with a semi-implicit time-stepping scheme, our method leads to the efficient and robust simulation of arbitrary curly filaments that exhibit rich, visually pleasing configurations and motion. Our approach was successfully applied to generate various scenarios such as the unwinding of a curled ribbon as well as the aesthetic animation of spiral-like hair or the fascinating growth of twining plants.
Mesh denoising via
L
0
minimization
Authors: He Lei , Schaefer Scott
Published: July 2013

We present an algorithm for denoising triangulated models based on
L
0
minimization. Our method maximizes the flat regions of the model and gradually removes noise while preserving sharp features. As part of this process, we build a discrete differential operator for arbitrary triangle meshes that is robust with respect to degenerate triangulations. We compare our method versus other anisotropic denoising algorithms and demonstrate that our method is more robust and produces good results even in the presence of high noise.
Semantic decomposition and reconstruction of residential scenes from LiDAR data
Authors: Lin Hui , Gao Jizhou , Zhou Yu , Lu Guiliang , Ye Mao , Zhang Chenxi , Liu Ligang , Yang Ruigang
Published: July 2013

We present a complete system to semantically decompose and reconstruct 3D models from point clouds. Different than previous urban modeling approaches, our system is designed for residential scenes, which consist of mainly low-rise buildings that do not exhibit the regularity and repetitiveness as high-rise buildings in downtown areas. Our system first automatically labels the input into distinctive categories using supervised learning techniques. Based on the semantic labels, objects in different categories are reconstructed with domain-specific knowledge. In particular, we present a novel building modeling scheme that aims to decompose and fit the building point cloud into
basic blocks
that are block-wise
symmetric
and
convex
. This building representation and its reconstruction algorithm are flexible, efficient, and robust to missing data. We demonstrate the effectiveness of our system on various datasets and compare our building modeling scheme with other state-of-the-art reconstruction algorithms to show its advantage in terms of both quality and speed.
Parsing sewing patterns into 3D garments
Authors: Berthouzoz Floraine , Garg Akash , Kaufman Danny M. , Grinspun Eitan , Agrawala Maneesh
Published: July 2013

We present techniques for automatically parsing existing sewing patterns and converting them into 3D garment models. Our parser takes a sewing pattern in PDF format as input and starts by extracting the set of panels and styling elements (e.g. darts, pleats and hemlines) contained in the pattern. It then applies a combination of machine learning and integer programming to infer how the panels must be stitched together to form the garment. Our system includes an interactive garment simulator that takes the parsed result and generates the corresponding 3D model. Our fully automatic approach correctly parses 68% of the sewing patterns in our collection. Most of the remaining patterns contain only a few errors that can be quickly corrected within the garment simulator. Finally we present two applications that take advantage of our collection of parsed sewing patterns. Our garment hybrids application lets users smoothly interpolate multiple garments in the 2D space of patterns. Our sketch-based search application allows users to navigate the pattern collection by drawing the shape of panels.
Path-space manipulation of physically-based light transport
Authors: Schmidt Thorsten-Walther , Novák Jan , Meng Johannes , Kaplanyan Anton S. , Reiner Tim , Nowrouzezahrai Derek , Dachsbacher Carsten
Published: July 2013

Industry-quality content creation relies on tools for lighting artists to quickly prototype, iterate, and refine final renders. As industry-leading studios quickly adopt physically-based rendering (PBR) across their art generation pipelines, many existing tools have become unsuitable as they address only simple effects without considering underlying PBR concepts and constraints. We present a novel light transport manipulation technique that operates directly on path-space solutions of the rendering equation. We expose intuitive direct and indirect manipulation approaches to edit complex effects such as (multi-refracted) caustics, diffuse and glossy indirect bounces, and direct/indirect shadows. With our sketch- and object-space selection, all built atop a parameterized regular expression engine, artists can search and isolate shading effects to inspect and edit. We classify and filter paths on the fly and visualize the selected transport phenomena. We survey artists who used our tool to manipulate complex phenomena on both static and animated scenes.
Handwriting beautification using token means
Authors: Zitnick C. Lawrence
Published: July 2013

In this paper, we propose a general purpose approach to handwriting beautification using online input from a stylus. Given a sample of writings, drawings, or sketches from the same user, our method improves a user's strokes in real-time as they are drawn. Our approach relies on one main insight. The appearance of the average of multiple instances of the same written word or shape is better than most of the individual instances. We utilize this observation using a two-stage approach. First, we propose an efficient real-time method for finding matching sets of stroke samples called tokens in a potentially large database of writings from a user. Second, we refine the user's most recently written strokes by averaging them with the matching tokens. Our approach works without handwriting recognition, and does not require a database of predefined letters, words, or shapes. Our results show improved results for a wide range of writing styles and drawings.
Subspace fluid re-simulation
Authors: Kim Theodore , Delaney John
Published: July 2013

We present a new subspace integration method that is capable of efficiently adding and subtracting dynamics from an existing high-resolution fluid simulation. We show how to analyze the results of an existing high-resolution simulation, discover an efficient reduced approximation, and use it to quickly "re-simulate" novel variations of the original dynamics. Prior subspace methods have had difficulty re-simulating the original input dynamics because they lack efficient means of handling semi-Lagrangian advection methods. We show that multi-dimensional
cubature
schemes can be applied to this and other advection methods, such as MacCormack advection. The remaining pressure and diffusion stages can be written as a single matrix-vector multiply, so as with previous subspace methods, no matrix inversion is needed at runtime. We additionally propose a novel importance sampling-based fitting algorithm that asymptotically accelerates the precomputation stage, and show that the Iterated Orthogonal Projection method can be used to elegantly incorporate moving internal boundaries into a subspace simulation. In addition to efficiently producing variations of the original input, our method can produce novel, abstract fluid motions that we have not seen from any other solver.
Probabilistic color-by-numbers
Authors: Lin Sharon , Ritchie Daniel , Fisher Matthew , Hanrahan Pat
Published: July 2013

We present a probabilistic factor graph model for automatically coloring 2D patterns. The model is trained on example patterns to statistically capture their stylistic properties. It incorporates terms for enforcing both color compatibility and spatial arrangements of colors that are consistent with the training examples. Using Markov Chain Monte Carlo, the model can be sampled to generate a diverse set of new colorings for a target pattern. This general probabilistic framework allows users to guide the generated suggestions via conditional inference or additional soft constraints. We demonstrate results on a variety of coloring tasks, and we evaluate the model through a perceptual study in which participants judged sampled colorings to be significantly preferable to other automatic baselines.
A new grid structure for domain extension
Authors: Zhu Bo , Lu Wenlong , Cong Matthew , Kim Byungmoon , Fedkiw Ronald
Published: July 2013

We present an efficient grid structure that extends a uniform grid to create a significantly larger far-field grid by dynamically extending the cells surrounding a fine uniform grid while still maintaining fine resolution about the regions of interest. The far-field grid preserves almost every computational advantage of uniform grids including cache coherency, regular subdivisions for parallelization, simple data layout, the existence of efficient numerical discretizations and algorithms for solving partial differential equations, etc. This allows fluid simulations to cover large domains that are often infeasible to enclose with sufficient resolution using a uniform grid, while still effectively capturing fine scale details in regions of interest using dynamic adaptivity.
Stereoscopic 3D line drawing
Authors: Kim Yongjin , Lee Yunjin , Kang Henry , Lee Seungyong
Published: July 2013

This paper discusses stereoscopic 3D imaging based on line drawing of 3D shapes. We describe the major issues and challenges in generating stereoscopic 3D effects using lines only, with a couple of relatively simple approaches called each-eye-based and center-eye-based. Each of these methods has its shortcomings, such as binocular rivalry and inaccurate lines. We explain why and how these problems occur, then describe the concept of stereo-coherent lines and an algorithm to extract them from 3D shapes. We also propose a simple method to stylize stereo lines that ensures the stereo coherence of stroke textures across binocular views. The proposed method provides viewers with unique visual experience of watching 2D drawings popping out of the screen like 3D.
Rectangling panoramic images via warping
Authors: He Kaiming , Chang Huiwen , Sun Jian
Published: July 2013

Stitched panoramic images mostly have irregular boundaries. Artists and common users generally prefer rectangular boundaries, which can be obtained through cropping or image completion techniques. In this paper, we present a content-aware warping algorithm that generates rectangular images from stitched panoramic images. Our algorithm consists of two steps. The first local step is mesh-free and preliminarily warps the image into a rectangle. With a grid mesh placed on this rectangle, the second global step optimizes the mesh to preserve shapes and straight lines. In various experiments we demonstrate that the results of our approach are often visually plausible, and the introduced distortion is often unnoticeable.
Non-polynomial Galerkin projection on deforming meshes
Authors: Stanton Matt , Sheng Yu , Wicke Martin , Perazzi Federico , Yuen Amos , Narasimhan Srinivasa , Treuille Adrien
Published: July 2013

This paper extends Galerkin projection to a large class of non-polynomial functions typically encountered in graphics. We demonstrate the broad applicability of our approach by applying it to two strikingly different problems: fluid simulation and radiosity rendering, both using deforming meshes. Standard Galerkin projection cannot efficiently approximate these phenomena. Our approach, by contrast, enables the compact representation and approximation of these complex non-polynomial systems, including quotients and roots of polynomials. We rely on representing each function to be model-reduced as a composition of tensor products, matrix inversions, and matrix roots. Once a function has been represented in this form, it can be easily model-reduced, and its reduced form can be evaluated with time and memory costs dependent only on the dimension of the reduced space.
Integer-grid maps for reliable quad meshing
Authors: Bommes David , Campen Marcel , Ebke Hans-Christian , Alliez Pierre , Kobbelt Leif
Published: July 2013

Quadrilateral remeshing approaches based on global parametrization enable many desirable mesh properties. Two of the most important ones are (1) high regularity due to explicit control over irregular vertices and (2) smooth distribution of distortion achieved by convex variational formulations. Apart from these strengths, state-of-the-art techniques suffer from limited reliability on real-world input data, i.e. the determined map might have degeneracies like (local) non-injectivities and consequently often cannot be used directly to generate a quadrilateral mesh. In this paper we propose a novel convex Mixed-Integer Quadratic Programming (MIQP) formulation which ensures by construction that the resulting map is within the class of so called Integer-Grid Maps that are guaranteed to imply a quad mesh. In order to overcome the NP-hardness of MIQP and to be able to remesh typical input geometries in acceptable time we propose two additional problem specific optimizations: a complexity reduction algorithm and singularity separating conditions. While the former decouples the dimension of the MIQP search space from the input complexity of the triangle mesh and thus is able to dramatically speed up the computation without inducing inaccuracies, the latter improves the continuous relaxation, which is crucial for the success of modern MIQP optimizers. Our experiments show that the reliability of the resulting algorithm does not only annihilate the main drawback of parametrization based quad-remeshing but moreover enables the global search for high-quality coarse quad layouts - a difficult task solely tackled by greedy methodologies before.
Flow reconstruction for data-driven traffic animation
Authors: Wilkie David , Sewall Jason , Lin Ming
Published: July 2013

'Virtualized traffic' reconstructs and displays continuous traffic flows from discrete spatio-temporal traffic sensor data or procedurally generated control input to enhance a sense of immersion in a dynamic virtual environment. In this paper, we introduce a fast technique to reconstruct traffic flows from in-road sensor measurements or procedurally generated data for interactive 3D visual applications. Our algorithm estimates the full state of the traffic flow from sparse sensor measurements (or procedural input) using a statistical inference method and a continuum traffic model. This estimated state then drives an agent-based traffic simulator to produce a 3D animation of vehicle traffic that statistically matches the original traffic conditions. Unlike existing traffic simulation and animation techniques, our method produces a full 3D rendering of individual vehicles as part of continuous traffic flows given discrete spatio-temporal sensor measurements. Instead of using a color map to indicate traffic conditions, users could visualize and fly over the reconstructed traffic in real time over a large digital cityscape.
A sort-based deferred shading architecture for decoupled sampling
Authors: Clarberg Petrik , Toth Robert , Munkberg Jacob
Published: July 2013

Stochastic sampling in time and over the lens is essential to produce photo-realistic images, and it has the potential to revolutionize real-time graphics. In this paper, we take an architectural view of the problem and propose a novel hardware architecture for efficient shading in the context of stochastic rendering. We replace previous caching mechanisms by a sorting step to extract coherence, thereby ensuring that only non-occluded samples are shaded. The memory bandwidth is kept at a minimum by operating on tiles and using new buffer compression methods. Our architecture has several unique benefits not traditionally associated with deferred shading. First, shading is performed in primitive order, which enables late shading of vertex attributes and avoids the need to generate a G-buffer of pre-interpolated vertex attributes. Second, we support state changes, e.g., change of shaders and resources in the deferred shading pass, avoiding the need for a single über-shader. We perform an extensive architectural simulation to quantify the benefits of our algorithm on real workloads.