EG2011

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https://diglib.eg.org/handle/10.2312/284

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HDR Photographic Pipeline for Camera Modules in Mobile Devices
(The Eurographics Association, 2011) Mantiuk, R.; Cybularczyk, J.; Cichowicz, M.; Smyk, M.; Bazyluk, B.; A. Day and R. Mantiuk and E. Reinhard and R. Scopigno
We replace the standard image capture pipeline in mobile phones with an HDR acquisition pipeline based on the multi-exposure method. We report timings for basic HDR algorithms implemented in a smartphone with ARMv6 processor and discuss programming techniques that speed-up execution and reduce RAM memory usage. The results compare favourably to proprietary iPhone 4 HDR implementation and show that the HDR pipeline can be efficiently implemented on existing camera phones using high-level APIs and no dedicated hardware.
High-Level Application Development for non-Computer Science majors using Image Processing
(The Eurographics Association, 2011) Shesh, Amit; S. Maddock and J. Jorge
In many ways it is a unique challenge to teach programming and high-level application development to noncomputer science majors like information systems. Simple visual computing can be a very helpful tool in such situations because it enables programs to produce something students can see. This paper describes a semesterlong experience of using image-processing as the theme in a course to teach programming and program design to students of information systems. Students progressively built a fairly complete image processing application from scratch in a bottom-up fashion using Java. They first concentrated on using low-level constructs like arrays and implementing several operations on them, and then supplemented their programs with features like a GUI complete with undo-redo features and capabilities to handle most standard image file formats. This allowed us to satisfy all the objectives of a typical programming course while simultaneously exposing students to developing meaningful applications from scratch with standard features. Our classroom was comprised of a mix of undergraduate and graduate students lacking sufficient programming background. With minor variations, our approach can be fit to courses for other majors where programming is considered useful but not critical.
Component-wise Controllers for Structure-Preserving Shape Manipulation
(The Eurographics Association and Blackwell Publishing Ltd., 2011) Zheng, Youyi; Fu, Hongbo; Cohen-Or, Daniel; Au, Oscar Kin-Chung; Tai, Chiew-Lan; M. Chen and O. Deussen
Recent shape editing techniques, especially for man-made models, have gradually shifted focus from maintaining local, low-level geometric features to preserving structural, high-level characteristics like symmetry and parallelism. Such new editing goals typically require a pre-processing shape analysis step to enable subsequent shape editing. Observing that most editing of shapes involves manipulating their constituent components, we introduce component-wise controllers that are adapted to the component characteristics inferred from shape analysis. The controllers capture the natural degrees of freedom of individual components and thus provide an intuitive user interface for editing. A typical model usually results in a moderate number of controllers, allowing easy establishment of semantic relations among them by automatic shape analysis supplemented with user interaction. We propose a component-wise propagation algorithm to automatically preserve the established inter-relations while maintaining the defining characteristics of individual controllers and respecting the user-specified modeling constraints. We extend these ideas to a hierarchical setup, allowing the user to adjust the tool complexity with respect to the desired modeling complexity. We demonstrate the effectiveness of our technique on a wide range of manmade models with structural features, often containing multiple connected pieces.
Interactive Modeling of City Layouts using Layers of Procedural Content
(The Eurographics Association and Blackwell Publishing Ltd., 2011) Lipp, Markus; Scherzer, Daniel; Wonka, Peter; Wimmer, Michael; M. Chen and O. Deussen
In this paper, we present new solutions for the interactive modeling of city layouts that combine the power of procedural modeling with the flexibility of manual modeling. Procedural modeling enables us to quickly generate large city layouts, while manual modeling allows us to hand-craft every aspect of a city. We introduce transformation and merging operators for both topology preserving and topology changing transformations based on graph cuts. In combination with a layering system, this allows intuitive manipulation of urban layouts using operations such as drag and drop, translation, rotation etc. In contrast to previous work, these operations always generate valid, i.e., intersection-free layouts. Furthermore, we introduce anchored assignments to make sure that modifications are persistent even if the whole urban layout is regenerated.
RTSAH Traversal Order for Occlusion Rays
(The Eurographics Association and Blackwell Publishing Ltd., 2011) Ize, Thiago; Hansen, Charles; M. Chen and O. Deussen
We accelerate the finding of occluders in tree based acceleration structures, such as a packetized BVH and a single ray kd-tree, by deriving the ray termination surface area heuristic (RTSAH) cost model for traversing an occlusion ray through a tree and then using the RTSAH to determine which child node a ray should traverse first instead of the traditional choice of traversing the near node before the far node. We further extend RTSAH to handle materials that attenuate light instead of fully occluding it, so that we can avoid superfluous intersections with partially transparent objects. For scenes with high occlusion, we substantially lower the number of traversal steps and intersection tests and achieve up to 2x speedups.
Image-based Retexturing of Deformed Surfaces from a Single Image
(The Eurographics Association, 2011) Hilsmann, A.; Schneider, D. C.; Eisert, P.; R. Laramee and I. S. Lim
Retexturing is the process of realistically replacing the texture of an object or surface in a given image by a new, synthetic one, such that texture distortion as well as lighting conditions of the original image are preserved. The key challenge is to separate the shading information from the actual local texture and to retrieve the texture distortion from an image without any knowledge of the underlying scene. In this paper, we introduce an approach for automatic retexturing that models an image of a deformed regular texture as a combination of its deformed surface albedo, a shading map and additional high frequency details.
Feature-Based Mesh Editing
(The Eurographics Association, 2011) Zhou, Qingnan; Weinkauf, Tino; Sorkine, Olga; N. Avis and S. Lefebvre
Editing and deformation of irregular meshes have become standard tools in geometric modeling. Most approaches try to preserve low-level differential properties of the surface during editing, whereas the global structure and shape of the features are not explicitly taken into account. In this paper, we introduce a feature-driven editing approach that puts global structural properties of the shape into the center of attention. We start by segmenting the mesh by ridges and valleys and use the so-defined curves and surface regions as intuitive handles for all subsequent editing operations. Our framework supports manipulations the positions and curvature values of the handles and the various mesh regions. In order to preserve the existing features, prevent unwanted appearance of new features, and maintain or manipulate global aspects of the shape, we apply curvature optimization in the affected areas. We show that the combination of feature extraction and curvature optimization leads to an intuitive modeling tool for high-quality surface manipulation.
Discovery of Intrinsic Primitives on Triangle Meshes
(The Eurographics Association and Blackwell Publishing Ltd., 2011) Solomon, Justin; Ben-Chen, Mirela; Butscher, Adrian; Guibas, Leonidas; M. Chen and O. Deussen
The discovery of meaningful parts of a shape is required for many geometry processing applications, such as parameterization, shape correspondence, and animation. It is natural to consider primitives such as spheres, cylinders and cones as the building blocks of shapes, and thus to discover parts by fitting such primitives to a given surface. This approach, however, will break down if primitive parts have undergone almost-isometric deformations, as is the case, for example, for articulated human models. We suggest that parts can be discovered instead by finding intrinsic primitives, which we define as parts that posses an approximate intrinsic symmetry. We employ the recently-developed method of computing discrete approximate Killing vector fields (AKVFs) to discover intrinsic primitives by investigating the relationship between the AKVFs of a composite object and the AKVFs of its parts. We show how to leverage this relationship with a standard clustering method to extract k intrinsic primitives and remaining asymmetric parts of a shape for a given k. We demonstrate the value of this approach for identifying the prominent symmetry generators of the parts of a given shape. Additionally, we show how our method can be modified slightly to segment an entire surface without marking asymmetric connecting regions and compare this approach to state-of-the-art methods using the Princeton Segmentation Benchmark.
User Manual on Augmented Reality for Installation and Maintenance of the V-Brakes System of a Mountain Bike
(The Eurographics Association, 2011) Martín-Gutiérrez, Jorge; Contero, Manuel; R. Laramee and I. S. Lim
Until now most traces of AR in applications related to mechanic and maintenance tasks has been performed in very specific systems which could be regarded as quite complex in the field they have been applied to (aircrafts, military equipment, etc.) In this paper we intend making this technology approachable for task and applications more common to everybody. We propose making one of the most frequent maintenance tasks in mountain bikes which is the installation of the brakes system and cartridge shoes as well as adjustment of the tension cable. They are not difficult tasks but making them the first few times may be quite tough for the average user. Therefore, we propose an easy interface based on augmented reality which fitted to the bike handlebars will guide the user step by step through installation of the V-brakes system, change of cartridge shoes and adjustment of tension cable. Interface is based in several cards containing markers with codified sequences based in 3D models for performing maintenance. User will use a mobile phone with camera or a head mounted display (HMD) connected to a PC so he may visualize the animated 3D models of pieces and tools needed for this operation. Virtual objects will be superimposed over the real ones so positions of each piece can be identified by the user before handling them. Final target is including the markers interface with the bike or brakes in their original purchase or making it available for download from a PC via web or as a mobile application.
BSSRDF Estimation from Single Images
(The Eurographics Association and Blackwell Publishing Ltd., 2011) Munoz, Adolfo; Echevarria, Jose I.; Seron, Francisco J.; Lopez-Moreno, Jorge; Glencross, Mashhuda; Gutierrez, Diego; M. Chen and O. Deussen
We present a novel method to estimate an approximation of the reflectance characteristics of optically thick, homogeneous translucent materials using only a single photograph as input. First, we approximate the diffusion profile as a linear combination of piecewise constant functions, an approach that enables a linear system minimization and maximizes robustness in the presence of suboptimal input data inferred from the image. We then fit to a smoother monotonically decreasing model, ensuring continuity on its first derivative. We show the feasibility of our approach and validate it in controlled environments, comparing well against physical measurements from previous works. Next, we explore the performance of our method in uncontrolled scenarios, where neither lighting nor geometry are known. We show that these can be roughly approximated from the corresponding image by making two simple assumptions: that the object is lit by a distant light source and that it is globally convex, allowing us to capture the visual appearance of the photographed material. Compared with previous works, our technique offers an attractive balance between visual accuracy and ease of use, allowing its use in a wide range of scenarios including off-the-shelf, single images, thus extending the current repertoire of real-world data acquisition techniques.
Improving BVH Ray Tracing Speed Using the AVX Instruction Set
(The Eurographics Association, 2011) Áfra, Attila T.; R. Laramee and I. S. Lim
High performance ray tracing on the CPU requires the efficient utilization of SIMD instructions. Ray packet and ray stream traversal algorithms achieve this by performing computations on multiple rays, nodes, or primitives at the same time. In this paper, we present our approach to optimizing coherent BVH ray packet tracing for the new AVX instruction set, which enables 8-wide SIMD operations on 32-bit floating-point numbers. We have measured an average speedup of about 50 percent compared to our SSE4.1 implementation, on an Intel Sandy Bridge processor.
Acoustic Rendering and Auditory-Visual Cross-Modal Perception and Interaction
(The Eurographics Association, 2011) Hulusic, Vedad; Harvey, Carlo; Tsingos, Nicolas; Debattista, Kurt; Walker, Steve; Howard, David; Chalmers, Alan; N. John and B. Wyvill
In recent years research in the 3-Dimensional sound generation field has been primarily focussed upon new applications of spatialised sound. In the computer graphics community the use of such techniques is most commonly found being applied to virtual, immersive environments. However, the field is more varied and diverse than this and other research tackles the problem in a more complete, and computationally expensive manner. However, simulation of light and sound wave propagation is still unachievable at a physically accurate spatio-temporal quality in real-time. Although the Human Visual System (HVS) and the Human Auditory System (HAS) are exceptionally sophisticated, they also contain certain perceptional and attentional limitations. Researchers, in fields such as psychology, have been investigating these limitations for several years and have come up with some findings which may be exploited in other fields. This STAR provides a comprehensive overview of the major techniques for generating spatialised sound and, in addition, discusses perceptual and cross-modal influences to consider. We also describe current limitations and provide an in-depth look at the emerging topics in the field.
Computer-Suggested Facial Makeup
(The Eurographics Association and Blackwell Publishing Ltd., 2011) Scherbaum, Kristina; Ritschel, Tobias; Hullin, Matthias; Thormählen, Thorsten; Blanz, Volker; Seidel, Hans-Peter; M. Chen and O. Deussen
Finding the best makeup for a given human face is an art in its own right. Experienced makeup artists train for years to be skilled enough to propose a best-fit makeup for an individual. In this work we propose a system that automates this task. We acquired the appearance of 56 human faces, both without and with professional makeup. To this end, we use a controlled-light setup, which allows to capture detailed facial appearance information, such as diffuse reflectance, normals, subsurface-scattering, specularity, or glossiness. A 3D morphable face model is used to obtain 3D positional information and to register all faces into a common parameterization. We then define makeup to be the change of facial appearance and use the acquired database to find a mapping from the space of human facial appearance to makeup. Our main application is to use this mapping to suggest the best-fit makeup for novel faces that are not in the database. Further applications are makeup transfer, automatic rating of makeup, makeup-training, or makeup-exaggeration. As our makeup representation captures a change in reflectance and scattering, it allows us to synthesize faces with makeup in novel 3D views and novel lighting with high realism. The effectiveness of our approach is further validated in a user-study.
Learning How to Match Fresco Fragments
(The Eurographics Association, 2011) Funkhouser, T.; Shin, H.; Toler-Franklin, C.; Castañeda, A. García; Brown, B.; Dobkin, D.; Rusinkiewicz, S.; Weyrich, T.; A. Day and R. Mantiuk and E. Reinhard and R. Scopigno
One of the main problems faced during reconstruction of fractured archaeological artifacts is sorting through a large number of candidate matches between fragments to find the relatively few that are correct. Previous computer methods for this task provided scoring functions based on a variety of properties of potential matches, including color and geometric compatibility across fracture surfaces. However, they usually consider only one or at most a few properties at once, and therefore provide match predictions with very low precision. In this paper, we investigate a machine learning approach that computes the probability that a match is correct based on the combination of many features. We explore this machine learning approach for ranking matches in three different sets of fresco fragments, finding that classifiers based on many match properties can be significantly more effective at ranking proposed matches than scores based on any single property alone. Our results suggest that it is possible to train a classifier on match properties in one data set and then use it to rank predicted matches in another data set effectively. We believe that this approach could be helpful in a variety of cultural heritage reconstruction systems.
Visual Analysis of Hierarchical Management Data
(The Eurographics Association, 2011) Geng, Zhao; Gathania, Gaurav; S.Laramee, Robert; Peng, ZhenMin; R. Laramee and I. S. Lim
The sales force management data at Thomson Reuters often contains multiple hierarchies and dependencies. Conventional business graphics are not sufficient for analyzing, presenting and exploring such data sets. The Treemap is effective for depicting hierarchical data, although it lacks structural clarity. Thus, distinguishing different levels within the treemap is difficult. In this abstract, we develop an interactive system for business analysts which enables structure-aware visualization of hierarchical data using multiple coordinated views. The design of this system includes hierarchy extraction, structure tracings and the direct manipulation of the treemap. We demonstrate our result on various sales force management data sets from Thomson Reuters.
Separable Approximation of Ambient Occlusion
(The Eurographics Association, 2011) Huang, Jing; Boubekeur, Tamy; Ritschel, Tobias; Holländer, Matthias; Eisemann, Elmar; N. Avis and S. Lefebvre
Ambient occlusion (AO) provides an effective approximation to global illumination that enjoys widespread use amongst practitioners. In this paper, we present a fast easy-to-implement separable approximation to screen space ambient occlusion. Computing occlusion first along a single direction and then transporting this occlusion into a second pass that is stochastically evaluating the final shading based on the AO estimates proves extremely efficient. Combined with interleaved sampling and geometry-aware blur, visually convincing results close to a non-separable occlusion can be obtained at much higher performance.
Using Procedural Modelling as a Framework for Representing Style: An Example from Regency Architecture
(The Eurographics Association, 2011) Calogero, Erica; Tyson, Nick; Arnold, David; Morris, David; A. Day and R. Mantiuk and E. Reinhard and R. Scopigno
This paper reports the use of shape grammars, as made available in CityEngine, to deconstruct six examples of Regency facades and uses them to form a reconstruction of Brunswick Square, in Brighton & Hove, UK. The aim of the research is to evaluate the potential for shape grammar rules to effectively encapsulate aspects of style in a formal, computational language. It is argued that such a system could both result in a stochastically based definition of Regency style with a measurable degree of certainty and enable the presentation of historical periods of history in a real-time virtual environment.
Visualising Semantic Pathways in Document Collections
(The Eurographics Association, 2011) Rowland, C.; Anderson, J.; R. Laramee and I. S. Lim
In this paper we discuss our investigation of the potential uses of animation and visualisation techniques for exploring unstructured text-based data. We reflect upon a design methodology that is rooted in art and design practice and introduce a conceptual model for following "semantic pathways" through document collections. We also describe an implementation of a working model of an interactive visualisation. We see potential applications for our conceptual model in domains where there is a requirement to infer narrative from multiple sources of evidence such as in counter-terrorism and criminal investigations.
LiveLayer Live Traffic Projection onto Maps
(The Eurographics Association, 2011) Walton, Simon; Chen, Min; Ebert, David; R. Laramee and I. S. Lim
We present our work-in-progress for a novel new approach to visualising real-time traffic data. The system provides for the projection of a number of camera video streams to their corresponding projections on a map so that viewers may view live traffic in real-time. Along with a user-friendly method of defining the projections that does not rely upon inaccurate computer vision techniques, we also discuss a number of interesting visualisation and technical challenges involved in such a system.
AVM-Explorer: Multi-Volume Visualization of Vascular Structures for Planning of Cerebral AVM Surgery
(The Eurographics Association, 2011) Weiler, Florian; Rieder, Christian; David, C. A.; Wald, C.; Hahn, Horst K.; K. Buehler and A. Vilanova
Arteriovenous malformations (AVMs) of the brain are rare vascular disorders characterized by the presence of direct connections between cerebral arteries and veins. Preoperative planning of AVM surgery is a challenging task. The neurosurgeon needs to gain a detailed understanding of both the pathoanatomy of the lesion as well as its location and spatial relation to critical functional areas and white matter fiber bundles at risk. A crucial element during this planning phase is the precise identification of feeding arteries, draining veins, and arteries en passage". To this end, a variety of imaging modalities for displaying neurovascular structures exists, both tomographic as well as projection based. However, the conventional 2D slice based review of such data is not well suited to help understanding the complex angioarchitecture of an AVM. In this paper, we demonstrate how stateof- the-art techniques from the fields of computer graphics and image processing can support neurosurgeons with the challenge of creating a mental 3D model of the lesion and understanding its internal structure. To evaluate the clinical value of our method, we present results from three case studies along with the medical assessment of an experienced neurosurgeon.

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