1,399 results
Search Results
2. The LivePaper system: augmenting paper on an enhanced tabletop
- Author
-
John Robinson and Charles Robertson
- Subjects
Human-Computer Interaction ,Computer science ,Human–computer interaction ,Computer graphics (images) ,General Engineering ,Design elements and principles ,Augmented reality ,Business card ,Computer Graphics and Computer-Aided Design ,Desk ,Visualization ,Rendering (computer graphics) - Abstract
The LivePaper system augments ordinary pieces of paper with projected information. Pages, cards and books are placed on an instrumented tabletop to activate their enhancement. To the user, it appears as if the paper gains new visual and auditory features. Projected annotations track the orientation and location of pages as the user moves them on the desktop. A piece of paper that is removed, but then returned to the desk, regains the same features that it previously exhibited. The LivePaper system accomplishes this by using features extracted from written material on the page, not from glyphs or other artificial marks. The paper describes both the system as a whole, and a number of sample applications we have developed to illustrate the feasibility of the LivePaper system. These applications include an architectural visualization tool, which projects a 3D hidden-line rendering of walls onto a page. The user may rotate and move the page to view the rendering from different angles. Another application is an audio player, which begins playing when a page (such as a business card) is laid on the desk. The user may control playback with his or her finger via projected buttons. Other applications include page-sharing, remote collaboration, and World Wide Web page viewing. From the user's perspective, all of these applications are attributes of the particular page, not features of the tabletop. Particular attention is given to the design of interaction: LivePaper is object-oriented, because the individual sheets are treated as computational units, but it also provides functions that involve several objects. The design principles applied to handle the different kinds of functionality are explained and illustrated in the LivePaper system, but are also proposed for wider use in augmented reality.
- Published
- 2001
3. Diffusion rendering of black ink paintings using new paper and ink models
- Author
-
Jintae Lee
- Subjects
Human-Computer Interaction ,Dynamic simulation ,Painting ,Inkwell ,Computer science ,Computer graphics (images) ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,Polygon mesh ,Computer Graphics and Computer-Aided Design ,ComputingMethodologies_COMPUTERGRAPHICS ,Rendering (computer graphics) - Abstract
A practical technique is presented for efficiently rendering oriental black ink paintings with realistic diffusion effects, being based on models which simulate a variety of paper types and black ink properties. Strokes can be generated by bristles or elastic brush models simulating those actually used in oriental black ink painting. Incorporation of paper modeling allows users to draw on a wide variety of papers having either randomly generated fiber meshes or uniform meshes commonly found in fabrics which are also frequently used. This accordingly provides a unique platform for real-time dynamic simulation of realistic ink diffusion in that the resultant diffusion images reflect the texture and the global change of gray tones as well as local temporal variations specific to a particular paper. Examples are presented demonstrating the capability of the proposed technique for handling different ink and paper properties.
- Published
- 2001
4. A photogrammetry-based verification of assumptions applied in the interpretation of paper architecture
- Author
-
Yu-Tun Tsai and Naai-Jung Shih
- Subjects
Theoretical computer science ,Process (engineering) ,Computer science ,Interpretation (philosophy) ,media_common.quotation_subject ,Perspective (graphical) ,General Engineering ,Space (commercial competition) ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Photogrammetry ,Deconstruction (building) ,Perception ,Architecture ,media_common - Abstract
This research investigated the space compositions of Chernikhov’s 101 Architectural Fantasies via computer-aided simulation to interpret the relationships between architectural components and spatial organization. An algorithmic approach and a perception approach were tested. Traditional analysis emphasized the simulation of corresponding objects by perspective deconstruction methods, which might not be able to show the exactly correct spatial relationship between objects. This research adopted photogrammetry to investigate the non-orthogonal spatial construction of 3D objects in 2D pictures. Research results showed that the algorithmic approach may derive different degrees of angles of parallel or intersected objects, and that observers tend to be misled by the effect of “orthogonal assumption” in terms of their own visual experiences. This finding revealed that Chernikhov had created unreasonable descriptions of space. This result was verified by the existence of false parallel and orthogonal relationships between drawn building parts. Three tests were conducted. Observers used a reverse verification process to analyze three-dimensional objects re-built in simulation. The verification mirrored a two-way construction relationship between 2D perspective and 3D models.
- Published
- 2002
5. Foreword to the special section on Computer Graphics in Brazil: A selection of papers from SIBGRAPI 2012
- Author
-
Carla Dal Sasso Freitas and Roberto Scopigno
- Subjects
Human-Computer Interaction ,Computer graphics ,Engineering drawing ,Computer science ,General Engineering ,Special section ,Computer Graphics and Computer-Aided Design ,Selection (genetic algorithm) - Published
- 2014
6. Special issue on executable papers for 3D object retrieval
- Author
-
Michela Spagnuolo and Remco C. Veltkamp
- Subjects
Human-Computer Interaction ,Information retrieval ,Computer science ,Programming language ,General Engineering ,Executable ,computer.file_format ,computer.software_genre ,Object (computer science) ,computer ,Computer Graphics and Computer-Aided Design ,Engineering(all) - Published
- 2013
- Full Text
- View/download PDF
7. Computer graphics in Spain: A selection of papers from CEIG 2009
- Author
-
Javier Lluch and Carlos Andujar
- Subjects
Human-Computer Interaction ,Computer graphics ,Computer science ,Computer graphics (images) ,General Engineering ,Computer Graphics and Computer-Aided Design ,Selection (genetic algorithm) - Published
- 2010
8. Computer graphics in Brazil: A selection of papers from SIBGRAPI 2006
- Author
-
Manuel M. Oliveira
- Subjects
Human-Computer Interaction ,Computer graphics ,Computer science ,Computer graphics (images) ,General Engineering ,Computer Graphics and Computer-Aided Design ,Selection (genetic algorithm) - Published
- 2008
9. Call for papers
- Author
-
JoséL. Encarnação
- Subjects
Human-Computer Interaction ,General Engineering ,Computer Graphics and Computer-Aided Design - Published
- 1983
10. Call for paper
- Author
-
JoséL. Encarnacao
- Subjects
Human-Computer Interaction ,General Engineering ,Computer Graphics and Computer-Aided Design - Published
- 1984
11. Diffusion-geometric maximally stable component detection in deformable shapes
- Author
-
Roee Litman, Michael M. Bronstein, and Alexander M. Bronstein
- Subjects
FOS: Computer and information sciences ,business.industry ,Computer Vision and Pattern Recognition (cs.CV) ,Computation ,Computer Science - Computer Vision and Pattern Recognition ,I.4.7 ,General Engineering ,Pattern recognition ,I.4.8 ,Geometric shape ,3d shapes ,Computer Graphics and Computer-Aided Design ,Full paper ,Human-Computer Interaction ,Diffusion geometry ,Artificial intelligence ,business ,Mathematics ,Shape analysis (digital geometry) - Abstract
Maximally stable component detection is a very popular method for feature analysis in images, mainly due to its low computation cost and high repeatability. With the recent advance of feature-based methods in geometric shape analysis, there is significant interest in finding analogous approaches in the 3D world. In this paper, we formulate a diffusion-geometric framework for stable component detection in non-rigid 3D shapes, which can be used for geometric feature detection and description. A quantitative evaluation of our method on the SHREC'10 feature detection benchmark shows its potential as a source of high-quality features.
- Published
- 2011
12. Displaced subdivision surfaces of animated meshes
- Author
-
Minsu Ahn, Hyunjun Lee, and Seungyong Lee
- Subjects
Computer science ,Graphics hardware ,Mesh networking ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Motion (geometry) ,Topology (electrical circuits) ,Volume mesh ,T-vertices ,Mathematics::Numerical Analysis ,Rendering (computer graphics) ,Computer graphics (images) ,Polygon mesh ,Subdivision surface ,Computer vision ,Static mesh ,ComputingMethodologies_COMPUTERGRAPHICS ,business.industry ,General Engineering ,Computer Graphics and Computer-Aided Design ,Full paper ,Vertex (geometry) ,Human-Computer Interaction ,Displacement mapping ,Computer Science::Graphics ,Artificial intelligence ,business - Abstract
This paper proposes a novel technique for converting a given animated mesh into a series of displaced subdivision surfaces. Instead of independently converting each mesh frame in the animated mesh, our technique produces displaced subdivision surfaces that share the same topology of the control mesh and a single displacement map. We first propose a conversion framework that enables sharing the same control mesh topology and a single displacement map among frames, and then present the details of the components in the framework. Each component is specifically designed to minimize the shape conversion errors that can be caused by enforcing a single displacement map. The resulting displaced subdivision surfaces have a compact representation, while reproducing the details of the original animated mesh. The representation can also be used for efficient rendering on modern graphics hardware that supports accelerated rendering of subdivision surfaces.
- Published
- 2011
13. Cyclic twill-woven objects
- Author
-
Jianer Chen, Yen-Lin Chen, Qing Xing, Jonathan L. Gross, and Ergun Akleman
- Subjects
Offset (computer science) ,Diagonal ,General Engineering ,Geometry ,Software_PROGRAMMINGTECHNIQUES ,Computer Graphics and Computer-Aided Design ,Full paper ,Human-Computer Interaction ,Topological graph theory ,Polygon mesh ,Weaving ,Algorithm ,ComputingMethodologies_COMPUTERGRAPHICS ,Mathematics - Abstract
Classical (or biaxial) twill is a textile weave in which the weft threads pass over and under two or more warp threads, with an offset between adjacent weft threads to give an appearance of diagonal lines. This paper introduces a theoretical framework for constructing twill-woven objects, i.e., cyclic twill-weavings on arbitrary surfaces, and it provides methods to convert polygonal meshes into twill-woven objects. It also develops a general technique to obtain exact triaxial-woven objects from an arbitrary polygonal mesh surface.
- Published
- 2011
14. Geometric models with weigthed topology
- Author
-
M. Attene and S. Biasotti
- Subjects
Strongly connected component ,General Engineering ,Topology ,Computer Graphics and Computer-Aided Design ,Full paper ,Human-Computer Interaction ,Robustness (computer science) ,Shape modeling ,Active shape model ,Segmentation ,Robustness ,Shape description ,Shape analysis (digital geometry) ,Applicability domain ,Mathematics - Abstract
This paper introduces the concept of weighted topology to model a 3D object whose connectivity and metric depend on a novel notion of weighted arc-length. The weighted arc-length between any two points of the shape takes into account the fact that a part of the object may be either weakly or strongly connected to another part. The new model is useful to treat problems which are intrinsically not robust to small topological changes. We describe an example implementation of the model and show how it can be exploited to (1) extend the applicability domain of existing segmentation algorithms and (2) improve the performances of a shape descriptor in a 3D object retrieval scenario.
- Published
- 2011
15. Direct quad-dominant meshing of point cloud via global parameterization
- Author
-
Bo Xu, Wujun Che, Xiaopeng Zhang, Yi-Kuan Zhang, and Er Li
- Subjects
Mathematical optimization ,Delaunay triangulation ,Scalar (mathematics) ,General Engineering ,Point cloud ,Computer Graphics and Computer-Aided Design ,Full paper ,Human-Computer Interaction ,Fully automatic ,Fairness measure ,Image-based meshing ,Algorithm ,Surface reconstruction ,ComputingMethodologies_COMPUTERGRAPHICS ,Mathematics - Abstract
In this paper, we present a new algorithm for quad-dominant meshing of unorganized point clouds based on periodic global parameterization. Our meshing method is guided by principal directions so as to preserve the intrinsic geometric properties. We use local Delaunay triangulation to smooth the initial principal directions and adapt the global parameterization to point clouds. By optimizing the fairness measure we can find the two scalar functions whose gradients best align with the guided principal directions. To handle the redundant vertices in the iso-lines due to overlapped triangles, an approach is specially designed to clean the iso-lines. Our approach is fully automatic and applicable to a surface of arbitrary genus. We also show an application of our method in curve skeleton extraction from incomplete point cloud data.
- Published
- 2011
16. Feature based volumes for implicit intersections
- Author
-
Turlif Vilbrandt, Pierre-Alain Fayolle, Alexander Pasko, Galina Pasko, and Oleg Fryazinov
- Subjects
Offset (computer science) ,General Engineering ,Topology ,Computer Graphics and Computer-Aided Design ,Constructive ,Full paper ,Visualization ,Human-Computer Interaction ,Bounding overwatch ,csi ,Feature based ,Function representation ,Algorithm ,Mathematics - Abstract
The automatic generation of volumes bounding the intersection of two implicit surfaces (isosurfaces of real functions of 3D point coordinates) or feature based volumes (FBV) is presented. Such FBVs are defined by constructive operations, function normalization and offsetting. By applying various offset operations to the intersection of two surfaces, we can obtain variations in the shape of an FBV. The resulting volume can be used as a boundary for blending operations applied to two corresponding volumes, and also for visualization of feature curves and modeling of surface based structures including microstructures.
- Published
- 2011
17. On visual complexity of 3D shapes
- Author
-
Waqar Saleem, Alexander Belyaev, Danyi Wang, and Hans-Peter Seidel
- Subjects
Theoretical computer science ,business.industry ,media_common.quotation_subject ,General Engineering ,Similarity matrix ,3d shapes ,Computer Graphics and Computer-Aided Design ,Full paper ,Visual complexity ,Human-Computer Interaction ,Active shape model ,Perception ,Computer vision ,Artificial intelligence ,business ,Scaling ,Shape analysis (digital geometry) ,Mathematics ,media_common - Abstract
We present an approach to compute the perceived complexity of a given 3D shape using the similarity between its views. Previous studies on 3D shape complexity relied on geometric and/or topological properties of the shape and are not appropriate for incorporating results from human shape perception which claim that humans perceive 3D shapes as organizations of 2D views. Therefore, we base our approach to computing 3D shape complexity on the (dis)similarity matrix of the shape's 2D views. To illustrate the application of our approach, we note that simple shapes lead to similar views whereas complex ones result in different, dissimilar views. This reflected in the View Similarity Graph (VSG) of a shape as tight clusters of points if the shape is simple and increasingly dispersed points as it gets more complex. To get a visual intuition of the VSG, we project it to 2D using Multi-Dimensional Scaling (MDS) and introduce measures to compute shape complexity through point dispersion in the resulting MDS plot. Experiments show that results obtained using our measures alleviate some of the drawbacks present in previous approaches.
- Published
- 2011
18. Context-aware garment modeling from sketches
- Author
-
Ron Maharik, Nathan A. Carr, Alla Sheffer, and Cody Robson
- Subjects
Multimedia ,Computer science ,media_common.quotation_subject ,General Engineering ,Context (language use) ,computer.software_genre ,Computer Graphics and Computer-Aided Design ,Geometric method ,Full paper ,Sketch ,Variety (cybernetics) ,Human-Computer Interaction ,Sketch-based modeling ,Human–computer interaction ,ComputerApplications_MISCELLANEOUS ,Perception ,Set (psychology) ,computer ,ComputingMethodologies_COMPUTERGRAPHICS ,media_common - Abstract
Modeling of realistic garments is essential for creating believable virtual environments. Sketch-based modeling of garments presents an appealing, easy to use alternative to the established modeling approaches which are time consuming and require significant tailoring expertise. Unfortunately, the results created using existing sketch-based methods lack realism. Driven by human perception of garment sketches, we propose a context-aware garment sketch interpretation based on a set of observations about key factors that affect the shape of garments. Based on this analysis we develop a geometric method for sketch-based modeling of garments which obtains more realistic results than previous techniques. We demonstrate the effectiveness of our method on a variety of inputs and validate our approach via a user study where viewers were asked to compare the believability of our outputs versus previous ones.
- Published
- 2011
19. Localized Cocone surface reconstruction
- Author
-
Ramsay Dyer, Lei Wang, and Tamal K. Dey
- Subjects
Correctness ,Delaunay triangulation ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,Reconstruction algorithm ,Topology ,Computer Graphics and Computer-Aided Design ,Full paper ,Smooth surface ,Human-Computer Interaction ,Octree ,Point (geometry) ,Surface reconstruction ,ComputingMethodologies_COMPUTERGRAPHICS ,Mathematics - Abstract
We introduce a surface reconstruction algorithm suitable for large point sets. The algorithm is an octree-based version of the Cocone reconstruction algorithm [4], allowing independent processing of small subsets of the total input point set. When the points are sufficiently sampled from a smooth surface, the global guarantee of topological correctness of the original algorithm is preserved, together with the geometric accuracy guarantees.
- Published
- 2011
20. Modeling (seemingly) impossible models
- Author
-
Gershon Elber
- Subjects
Class (computer programming) ,Computer science ,General Engineering ,Realization (linguistics) ,3d model ,Computer Graphics and Computer-Aided Design ,Two stages ,Full paper ,Human-Computer Interaction ,Computer graphics ,Derivative work ,Hardware_GENERAL ,Computer graphics (images) ,Geometric modeling - Abstract
In recent years, there has been a growing interest in computer graphics and geometric modeling in the ability to create and manipulate seemingly impossible models (SIMs). Methods to create derivative work and modify drawings and paintings of SIMs made by artists were suggested. Similarly, 3D realization of SIMs of some of these drawings were also offered. In this work, we further explore the nature of SIMs and identify a class of SIMs that can be realized and modeled in 3D. As part of this analysis we show an invariance whose preservation allows one to model SIM artifacts that are completely realizable. We further present a mini-modeling package that allow end-users to realize whole new SIMs in two stages: modeling a regular 3D model and then converting it into a SIM using special deformations. We conclude with some examples, a discussion on the current limitations and a layout of possible future work.
- Published
- 2011
21. Interactive 3D caricature from harmonic exaggeration
- Author
-
Adelailson Peixoto, Luiz Velho, Thales Vieira, Dimas Martínez, Vinícius Mello, and Thomas Lewiner
- Subjects
Harmonic filtering ,Computer science ,business.industry ,Quantitative Biology::Tissues and Organs ,media_common.quotation_subject ,Interactive 3d ,General Engineering ,Computer Graphics and Computer-Aided Design ,Full paper ,Rendering (computer graphics) ,Human-Computer Interaction ,Interactivity ,Computer graphics (images) ,Exaggeration ,Computer vision ,Polygon mesh ,Artificial intelligence ,business ,media_common - Abstract
A common variant of caricature relies on exaggerating characteristics of a shape that differs from a reference template, usually the distinctive traits of a human portrait. This work introduces a caricature tool that interactively emphasizes the differences between two three-dimensional meshes. They are represented in the manifold harmonic basis of the shape to be caricatured, providing intrinsic controls on the deformation and its scales. It further provides a smooth localization scheme for the deformation. This lets the user edit the caricature part by part, combining different settings and models of exaggeration, all expressed in terms of harmonic filter. This formulation also allows for interactivity, rendering the resulting 3d shape in real time.
- Published
- 2011
22. SketchCleanNet — A deep learning approach to the enhancement and correction of query sketches for a 3D CAD model retrieval system
- Author
-
Bharadwaj Manda, Prasad Pralhad Kendre, Subhrajit Dey, and Ramanathan Muthuganapathy
- Subjects
FOS: Computer and information sciences ,Human-Computer Interaction ,Computer Science - Machine Learning ,Artificial Intelligence (cs.AI) ,Computer Science - Artificial Intelligence ,Computer Vision and Pattern Recognition (cs.CV) ,Computer Science - Computer Vision and Pattern Recognition ,General Engineering ,Computer Graphics and Computer-Aided Design ,Machine Learning (cs.LG) - Abstract
Search and retrieval remains a major research topic in several domains, including computer graphics, computer vision, engineering design, etc. A search engine requires primarily an input search query and a database of items to search from. In engineering, which is the primary context of this paper, the database consists of 3D CAD models, such as washers, pistons, connecting rods, etc. A query from a user is typically in the form of a sketch, which attempts to capture the details of a 3D model. However, sketches have certain typical defects such as gaps, over-drawn portions (multi-strokes), etc. Since the retrieved results are only as good as the input query, sketches need cleaning-up and enhancement for better retrieval results. In this paper, a deep learning approach is proposed to improve or clean the query sketches. Initially, sketches from various categories are analysed in order to understand the many possible defects that may occur. A dataset of cleaned-up or enhanced query sketches is then created based on an understanding of these defects. Consequently, an end-to-end training of a deep neural network is carried out in order to provide a mapping between the defective and the clean sketches. This network takes the defective query sketch as the input and generates a clean or an enhanced query sketch. Qualitative and quantitative comparisons of the proposed approach with other state-of-the-art techniques show that the proposed approach is effective. The results of the search engine are reported using both the defective and enhanced query sketches, and it is shown that using the enhanced query sketches from the developed approach yields improved search results.
- Published
- 2022
23. Simple implementation and low computational cost simulation of curved folds based on ruling-aware triangulation
- Author
-
Kosuke Sasaki and Jun Mitani
- Subjects
Developable surface ,Discretization ,Ruled surface ,Computer science ,General Engineering ,Process (computing) ,Triangulation (social science) ,Folding (DSP implementation) ,Computer Science::Computational Geometry ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Simple (abstract algebra) ,Triangle mesh ,Algorithm ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
Folding a thin sheet material such as paper along curves creates a developable surface composed of ruled surface patches. When using such surfaces in design, designers often repeat a process of folding along curves drawn on a sheet and checking the folded shape. Although several methods for constructing such shapes on a computer have been proposed, it is still difficult to check the folded shapes instantly from the crease patterns. In this paper, we propose a simple method that approximately realizes a simulation of curved folds with a triangular mesh from its crease pattern. The proposed method first approximates curves in a crease pattern with polylines and then generates a triangular mesh. In order to construct the discretized developable surface, the edges in the mesh are rearranged so that they align with the estimated rulings. The proposed method is characterized by its simplicity and is implemented on an existing origami simulator that runs in a web browser.
- Published
- 2022
24. DIMNet: Dense implicit function network for 3D human body reconstruction
- Author
-
Nam Ling, Shufang Zhang, Jiang Liu, and Yuhong Liu
- Subjects
Marching cubes ,Computer science ,business.industry ,Deep learning ,3D reconstruction ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,02 engineering and technology ,Perceptron ,Computer Graphics and Computer-Aided Design ,Convolution ,Human-Computer Interaction ,Feature (computer vision) ,0202 electrical engineering, electronic engineering, information engineering ,RGB color model ,020201 artificial intelligence & image processing ,Computer vision ,Artificial intelligence ,Additive smoothing ,business - Abstract
In recent years, with the improvement of artificial intelligence technology, it has become possible to reconstruct high-precision 3D human body models based on ordinary RGB images. The current 3D human body reconstruction technology requires complex external equipment to scan all angles of the human body, which is complicated to be implemented and cannot be popularized. In order to solve this problem, this paper applies deep learning models on reconstructing 3D human body based on monocular images. First of all, this paper uses Stacked Hourglass network to perform convolution operations on monocular images collected from different views. Then Multi-Layer Perceptrons (MLPs) are used to decode the encoded high-level images. The feature codes in the two views(main and side) are fused, and the interior and exterior points are classified by the fusion features, so as to obtain the corresponding 3D occupancy field. At last, the Marching Cube algorithm is used for 3D reconstruction with a specific threshold and then we use Laplace smoothing algorithm to remove artifacts. This paper proposes a dense sampling strategy based on the important joint points of the human body, which has a certain optimization effect on the realization of high-precision 3D reconstruction. The performance of the proposed scheme has been validated on the open source datasets, MGN dataset and the THuman dataset, provided by Tsinghua University. The proposed scheme can reconstruct features such as clothing folds, color textures, and facial details,and has great potential to be applied in different applications.
- Published
- 2021
25. Conjugate shape simplification via precise algebraic planar sweeps toward gear design
- Author
-
Jinesh Machchhar, Gershon Elber, and Henry Segerman
- Subjects
Computer science ,General Engineering ,Process (computing) ,Motion (geometry) ,Physics::Classical Physics ,Topology ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Planar ,Transmission (telecommunications) ,Robustness (computer science) ,Variety (universal algebra) ,Algebraic number ,Reduction (mathematics) - Abstract
Gears play a pivotal role in machine design. This paper proposes an algorithm to simplify the shapes of planar gears. This is achieved via iterative conjugation, using precise algebraic sweeps. The notion of shape simplification is introduced in a mathematically rigorous manner and it is shown that the conjugation process converges, yielding a pair of meshing gears that follow the desired motion. Simplified gear shapes may lead to improved mechanical characteristics and reduction in manufacturing costs. The generality of algebraic sweeps allows precise design of gears with freeform shapes and non-uniform motion transmission. Moreover, the computational framework proposed in this paper is versatile, with applications beyond gear design. A variety of examples from an implementation of our algorithm, that offers topological guarantees, are presented, which demonstrate the robustness and efficacy of our approach.
- Published
- 2020
26. Boundary particle resampling for surface reconstruction in liquid animation
- Author
-
Paulo Pagliosa, Afonso Paiva, Nicolas Oe, Douglas Cedrim, and Marcos Sandim
- Subjects
Boundary detection ,Computer science ,General Engineering ,020207 software engineering ,02 engineering and technology ,Animation ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Computer graphics ,Robustness (computer science) ,Surface fitting ,Resampling ,Principal component analysis ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Algorithm ,Surface reconstruction - Abstract
In this paper, we present a novel adaptive particle resampling method tailored for surface reconstruction of level-sets defined by the boundary particles from a particle-based liquid simulation. The proposed approach is simple and easy to implement, and only requires the positions of the particles to identify and refine regions with small and thin fluid features accurately. The method comprises four main stages: boundary detection, feature classification, particle refinement, and surface reconstruction. For each simulation frame, firstly the free-surface particles are captured through a boundary detection method. Then, the boundary particles are classified and labeled according to the deformation and the stretching of the free-surface computed from the Principal Component Analysis (PCA) of the particle positions. The particles placed at feature regions are then refined according to their feature classification. Finally, we extract the free-surface of the zero level-set defined by the resampled boundary particles and its normals. In order to render the free-surface, we demonstrate how the traditional methods of surface fitting in Computer Graphics and Computational Physics literature can benefit from the proposed resampling method. Furthermore, the results shown in the paper attest the effectiveness and robustness of our method when compared to state-of-the-art adaptive particle resampling techniques.
- Published
- 2019
27. Foreword to the Special Section on Smart Tool and Applications for Graphics (STAG 2020)
- Author
-
Silvia Biasotti, Stefano Berretti, and Ruggero Pintus
- Subjects
Human-Computer Interaction ,Tree (data structure) ,Cover (telecommunications) ,Computer science ,Computer graphics (images) ,Motion blur ,General Engineering ,Special section ,Graphics ,Data structure ,Computer Graphics and Computer-Aided Design ,Motion (physics) ,Visual computing - Abstract
This special issue contains extended and revised versions of the best papers presented at the 7th Conference on Smart Tools and Applications in Graphics (STAG 2020), held virtually on November 12–13, 2020. The two selected papers cover two different visual computing domains. The first contribution proposes a novel Level-of-Detail data structure (Motion Tree) to efficiently render motion blur of animated objects, while the second contribution presents an evaluation of current deep-learning based 3D registration solutions.
- Published
- 2021
28. Edge topology construction of Voronoi diagrams of spheres in non-general position
- Author
-
Sara McMains, Adarsh Krishnamurthy, Iddo Hanniel, and Xiang Li
- Subjects
Computer science ,Modulo ,MathematicsofComputing_GENERAL ,General Engineering ,020207 software engineering ,02 engineering and technology ,Computer Science::Computational Geometry ,Topology ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Bounding overwatch ,Medial axis ,Robustness (computer science) ,TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,0202 electrical engineering, electronic engineering, information engineering ,Mathematics::Metric Geometry ,020201 artificial intelligence & image processing ,Cube ,Voronoi diagram ,General position ,ComputingMethodologies_COMPUTERGRAPHICS ,MathematicsofComputing_DISCRETEMATHEMATICS ,Parametric statistics - Abstract
Although 3D Voronoi diagrams and medial axis transforms have numerous applications in biology, robotics, and manufacturing, most researchers use Voronoi diagrams of points instead of the true 3D input geometry, due to issues of robustness and scalability. In this paper, we present a robust sample-based GPU algorithm for calculating the full topology of Voronoi diagrams of non-general position spheres. Prior work demonstrated that the presence, geometry, and combinatorial basis of spheres that contribute to Voronoi vertices can be efficiently computed by shooting rays from each input sphere, mapping ray intersections with the nearest bisector surface to parametric bounding cubes, and analyzing the results. In this paper, we propose an algorithm on this parametric bounding cube to compute Voronoi edges in addition to the vertices. We successfully extract the full topology of the Voronoi diagram, including special cases such as isolated Voronoi edges that do not contain Voronoi vertices, more than three Voronoi edges emanating from a Voronoi vertex, and Voronoi edges that are shared by more than three Voronoi cells. Our GPU implementation efficiently and robustly handles all input, whether in general or non-general position, and finds all Voronoi vertices and edges, modulo the sampling density, including isolated disconnected edges.
- Published
- 2019
29. EvalViz – Surface visualization evaluation wizard for depth and shape perception tasks
- Author
-
Monique Meuschke, Kai Lawonn, Noeska N. Smit, Bernhard Preim, and Nils Lichtenberg
- Subjects
Creative visualization ,Computer science ,media_common.quotation_subject ,General Engineering ,020207 software engineering ,02 engineering and technology ,Wizard ,Computer Graphics and Computer-Aided Design ,Visualization ,Human-Computer Interaction ,User studies ,Human–computer interaction ,Perception ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,User interface ,media_common ,Coding (social sciences) - Abstract
User studies are indispensable for visualization application papers in order to assess the value and limitations of the presented approach. Important aspects are how well depth and shape information can be perceived, as coding of these aspects is essential to enable an understandable representation of complex 3D data. In practice, there is usually little time to perform such studies, and the establishment and conduction of user studies can be labour-intensive. In addition, it can be difficult to reach enough participants to obtain expressive results regarding the quality of different visualization techniques. In this paper, we propose a framework that allows visualization researchers to quickly create task-based user studies on depth and shape perception for different surface visualizations and perform the resulting tasks via a web interface. With our approach, the effort for generating user studies is reduced and at the same time the web-based component allows researchers to attract more participants to their study. We demonstrate our framework by applying shape and depth evaluation tasks to visualizations of various surface representations used in many technical and biomedical applications.
- Published
- 2019
30. Hybrid modeling of Lagrangian–Eulerian method for high-speed fluid simulation
- Author
-
Shenfan Zhang, Hong Qin, Changbo Wang, and Chen Li
- Subjects
Computer science ,Perspective (graphical) ,General Engineering ,020207 software engineering ,Eulerian path ,02 engineering and technology ,Animation ,Solver ,Computer Graphics and Computer-Aided Design ,Computational science ,Human-Computer Interaction ,symbols.namesake ,Distortion ,Synchronization (computer science) ,0202 electrical engineering, electronic engineering, information engineering ,symbols ,Particle ,020201 artificial intelligence & image processing ,Graphics ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
This paper proposes a hybrid Lagrangian–Eulerian method involving all participating media for high-speed fluid simulation and its accompanying phenomena. We take advantages of both particle- and grid-based solvers in our new approach by dividing all the physical states into two different parts based on their individual characteristics. Lagrangian-based solver gives rise to liquid, droplet, and foam creation and facilitates the drastic shape distortion and state transition during the multi-physical processes simulation from the perspective of individual particles. At the same time, Eulerian-based solver mainly focuses on the animation of spray, which enables a fog-like atmosphere. Essential to all of the aforementioned functionalities is the state transition among different media considering both physical and geometric features in this paper. The state transition enables to streamline the dis-association and generation of certain physical states. Moreover, to ensure the synchronization of hybrid models, we establish essential interaction and build tight coupling between the particle- and grid-based subsystems. With the comprehensive experimental results, we have manifested that our new modeling approach is both effective and highly modularized, and is capable of producing convincing visual effects for a wider range of graphics and animation tasks.
- Published
- 2019
31. Design considerations for combining augmented reality with intelligent tutors
- Author
-
Bradley M. Herbert, Amali Weerasinghe, Barrett Ens, Grant Wigley, Mark Billinghurst, Herbert, Bradley, Ens, Barrett, Weerasinghe, Amali, Billinghurst, Mark, and Wigley, Grant
- Subjects
experiential learning ,Computer science ,05 social sciences ,General Engineering ,050301 education ,Kinesthetic learning ,020207 software engineering ,Context (language use) ,02 engineering and technology ,Overlay ,Computer Graphics and Computer-Aided Design ,Experiential learning ,augmented reality ,intelligent tutoring systems ,Human-Computer Interaction ,kinaesthetic learning ,Human–computer interaction ,human computer interaction ,0202 electrical engineering, electronic engineering, information engineering ,Augmented reality ,Learning support ,computers and learning ,User interface ,psychomotor learning ,0503 education - Abstract
In this paper, we review Augmented Reality Training systems and how they can be combined with Intelligent Tutoring Systems to improve pedagogical outcomes on spatial learning tasks. Intelligent Tutoring Systems (ITSs) are computer-based systems that provide personalised feedback, learner support and task selection by modelling learner knowledge. They have been shown to significantly improve learning, however currently provide little support for psychomotor tasks that involve spatial learning. For such tasks, ITSs may not be able to present instruction in an intuitive manner for mental model reconstruction. Augmented Reality (AR) overlays 3-Dimensional virtual objects on the real world, and has been shown to be useful for training in physical manipulation tasks. However, most current AR training systems provide only step by step instructions and do not adapt training content to user needs. In this paper we show how combining ITS with AR systems has the potential to overcome the limitations of both approaches and produce a significantly improved learning experience. We provide examples of previous work in this area, and provide guidelines for future AR ITS systems. Refereed/Peer-reviewed
- Published
- 2018
32. KinetiX - designing auxetic-inspired deformable material structures
- Author
-
Jifei Ou, Nikolaos Vlavianos, Zhao Ma, Jannik Peters, Hiroshi Ishii, and Dai Sen
- Subjects
Shearing (physics) ,Auxetics ,Computer science ,General Engineering ,Hinge ,Mechanical engineering ,020207 software engineering ,02 engineering and technology ,Bending ,Degrees of freedom (mechanics) ,021001 nanoscience & nanotechnology ,Compression (physics) ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Transformation (function) ,0202 electrical engineering, electronic engineering, information engineering ,0210 nano-technology ,Scaling - Abstract
This paper describes a group of auxetic-inspired material structures that can transform into various shapes upon compression. We developed four cellular-based material structure units composed of rigid plates and elastic/rotary hinges. Different compositions of these units lead to a variety of tunable shape-changing possibilities, such as uniform scaling, shearing, bending and rotating. By tessellating those transformations together, we can create various higher level transformations for product design. In the paper, we first give a geometrical and numerical description of the units’ configuration and their degrees of freedom. An interactive simulation tool is developed for users to input designed structures and preview the transformation. Finally we present three application prototypes that utilize our proposed structures.
- Published
- 2018
33. 2D skeleton extraction based on heat equation
- Author
-
Shanshan Gao, Guangshun Wei, Shiqing Xin, Yuanfeng Zhou, and Fengyi Gao
- Subjects
Computer science ,Binary image ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Skeletonization ,Human-Computer Interaction ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Heat equation ,Distance transform ,Algorithm ,ComputingMethodologies_COMPUTERGRAPHICS ,Shape analysis (digital geometry) - Abstract
Object skeleton is a useful geometric tool for shape analysis tasks. It encodes the topological structure of the primitive shape and preserves a geometric cue as well. Skeletonization is a seemingly simple but difficult research problem. A desirable skeletonization algorithm has to be topologically complete, insensitive to boundary noise, without any branch pruning and free of user-specified parameters. In this paper, we propose a novel method based on the heat equation to extract skeletons assuming that the input is a binary image. Based on the connection between the skeleton and ridge lines, we use the smooth heat diffusion height surface to approximate the real distance field, and then extract the ridge lines of the surface as the output skeleton. Different from the existing approaches, the proposed method in this paper has the above-mentioned excellent properties and can capture the clean and stable skeleton directly. Extensive experimental results show that the new approach can yield better skeletons than the state-of-the-art.
- Published
- 2018
34. Real-time animation of human characters’ anatomy
- Author
-
Marcos Garcia, Antoine Serrurier, Aaron Sújar, and Juan José Casafranca
- Subjects
Computer science ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,02 engineering and technology ,Animation ,Anatomy ,Computer Graphics and Computer-Aided Design ,Pipeline (software) ,030218 nuclear medicine & medical imaging ,Human-Computer Interaction ,Computer graphics ,03 medical and health sciences ,Skinning ,0302 clinical medicine ,Interactivity ,Workflow ,0202 electrical engineering, electronic engineering, information engineering ,Skeletal animation ,Dual quaternion ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
The animation of articulated characters is a central problem in the computer graphics field. Skeletal animation techniques define a workflow which has proven to be effective for boundary representations (B-Reps). This paper extends the classical skeletal animation pipeline to deal with characters internal tissues. In contrast to most common approaches, the proposed technique automates all the stages of this workflow. Well known skinning algorithms, such as Linear Blending Skinning, Dual Quaternion Skinning or Optimized Centers of Rotation were adapted to allow the use of our technique in applications where interactivity is required. The pipeline proposed in this paper can be used in many computer graphics systems such as games or educational applications to visualize and animate the internal anatomy of a virtual character at interactive rates.
- Published
- 2018
35. Heuristic misfit reduction: A programmable approach for 3D garment fit customization
- Author
-
Wonseop Lee and Hyeong-Seok Ko
- Subjects
0209 industrial biotechnology ,Landmark ,Computer science ,Heuristic ,General Engineering ,020207 software engineering ,02 engineering and technology ,Landmark point ,Computer Graphics and Computer-Aided Design ,Personalization ,Human-Computer Interaction ,Reduction (complexity) ,020901 industrial engineering & automation ,Line (geometry) ,0202 electrical engineering, electronic engineering, information engineering ,Algorithm ,Simulation - Abstract
Based on the physically-based clothing simulation, this paper develops a novel method to customize the fit of the given garment to the reference body. The method defines three misfit measures, namely the landmark point misfit, landmark line misfit, and circumferential misfit, based on the correspondence between the landmark points and landmark lines in the body and garment. In terms of the above misfit measures, this paper proposes the heuristic misfit reduction method. The heuristic misfit reduction method works in the following way. Starting from a given preliminary garment, it (1) performs the fit evaluation, (2) modifies the panels based on the evaluation to enhance the fit, then (3) performs the draping simulation with the modified panels. The procedure is repeated until a satisfactory fit is achieved. According to our experiments, the proposed method successfully customizes a given garment to fit to the given body.
- Published
- 2018
36. Sequence searching with CNN features for robust and fast visual place recognition
- Author
-
Chaoqun Wang, Xuejun Yang, Dongdong Bai, Xiaodong Yi, and Bo Zhang
- Subjects
0209 industrial biotechnology ,Sequence ,Matching (graph theory) ,Computer science ,business.industry ,Deep learning ,media_common.quotation_subject ,General Engineering ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Adaptability ,Image (mathematics) ,Human-Computer Interaction ,Range (mathematics) ,Acceleration ,020901 industrial engineering & automation ,0202 electrical engineering, electronic engineering, information engineering ,Feature (machine learning) ,020201 artificial intelligence & image processing ,Computer vision ,Artificial intelligence ,business ,media_common - Abstract
The primary purpose of this paper is to realize robust place recognition algorithms towards simultaneous viewpoint and condition changes, and provide satisfactory computational efficiency. In this paper, we significantly improve the viewpoint invariance of the SeqSLAM algorithm by using state-of-the-art deep learning techniques to generate robust feature representations of images and develop the SeqCNNSLAM. Experimental results show that SeqCNNSLAM outperforms state-of-the-art place recognition systems in most cases, such as, when precision is maintained at 100%, the maximum recall obtained by SeqCNNSLAM is 50% higher than SeqSLAM on the Norland dataset with simultaneous condition change and 12.5% viewpoint change. Besides, we develop an acceleration method called A-SeqCNNSLAM, which exploits the location relationship between the matching images of adjacent images to reduce the matching range of the current image. Experimental results demonstrate that an acceleration of ∼ 5 times is achieved with minimal accuracy degradation of ∼ 5%. Finally, to enable A-SeqCNNSLAM adaptability in new environments, O-SeqCNNSLAM is devised for the online parameter adjustment in A-SeqCNNSLAM.
- Published
- 2018
37. Position based simulation of solids with accurate contact handling
- Author
-
Florica Moldoveanu and Mihai Frâncu
- Subjects
Coupling ,Mathematical optimization ,General Engineering ,020207 software engineering ,02 engineering and technology ,Solver ,Computer Graphics and Computer-Aided Design ,Position based dynamics ,Regularization (mathematics) ,Finite element method ,Human-Computer Interaction ,Nonlinear system ,Integrator ,Convex optimization ,0202 electrical engineering, electronic engineering, information engineering ,Applied mathematics ,020201 artificial intelligence & image processing ,Mathematics - Abstract
Simulating multi-body dynamics with both rigid and flexible parts and with frictional contacts is a hard problem. We solve this by expressing the couplings between the bodies as position level constraints. The implicit treatment of the constraint directions gives us improved stability over velocity based methods. Then by employing regularization of nonlinear constraints and a convex minimization formulation, we bridge constraint-based methods to traditional force-based methods. In fact, the former are just a dual variables formulation of the latter. We solve this dual problem using position based dynamics (PBD). We show how PBD is a completely valid modeling technique and we extend it with an accurate contact and Coulomb friction model. We further show for the first time how the same solver can be used to simulate both rigid and deformable solids with two way coupling. For the soft bodies we introduce a novel form of linear finite elements expressed as constraints, that is more accurate than PBD mass-spring systems. More of our results include the energy conserving Newmark integrator and the accelerated Jacobi solver suitable for parallel architectures. Note that this paper is an extended and revised version of the conference paper published in [1].
- Published
- 2017
38. Humans are easily fooled by digital images
- Author
-
Victor Schetinger, Manuel M. Oliveira, Tiago Carvalho, and Roberto da Silva
- Subjects
FOS: Computer and information sciences ,Information retrieval ,Computer science ,Computer Vision and Pattern Recognition (cs.CV) ,Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Human-Computer Interaction ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,Subject (documents) ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Graphics (cs.GR) ,Human-Computer Interaction (cs.HC) ,Image (mathematics) ,Human-Computer Interaction ,Digital image ,Computer Science - Graphics ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Social media ,Digital image forensics - Abstract
Digital images are ubiquitous in our modern lives, with uses ranging from social media to news, and even scientific papers. For this reason, it is crucial evaluate how accurate people are when performing the task of identify doctored images. In this paper, we performed an extensive user study evaluating subjects capacity to detect fake images. After observing an image, users have been asked if it had been altered or not. If the user answered the image has been altered, he had to provide evidence in the form of a click on the image. We collected 17,208 individual answers from 383 users, using 177 images selected from public forensic databases. Different from other previously studies, our method propose different ways to avoid lucky guess when evaluating users answers. Our results indicate that people show inaccurate skills at differentiating between altered and non-altered images, with an accuracy of 58%, and only identifying the modified images 46.5% of the time. We also track user features such as age, answering time, confidence, providing deep analysis of how such variables influence on the users' performance.
- Published
- 2017
39. Interactive modeling of smooth manifold meshes with arbitrary topology: G1 stitched bi-cubic Bézier patches
- Author
-
Jianer Chen, Ergun Akleman, and Vinod Srinivasan
- Subjects
Bézier surface ,Surface (mathematics) ,Smoothness ,Quadrilateral ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,02 engineering and technology ,Topology ,Computer Graphics and Computer-Aided Design ,Manifold ,Human-Computer Interaction ,Computer Science::Graphics ,Parametric surface ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Polygon mesh ,Smooth structure ,ComputingMethodologies_COMPUTERGRAPHICS ,Mathematics - Abstract
In this paper, we present a new piecewise parametric approach to obtain smooth surfaces from any given orientable 2-manifold polynomial control mesh. Our approach provides C 2 continuous Bi-Cubic Bezier patches that are guaranteed to be stitched with G 1 continuity regardless of the underlying mesh topology. A high level summary of the approach can be given as a two-step process: (1) Starting from an orientable 2-manifold mesh we apply vertex-insertion, which is remeshing algorithm of Catmull–Clark subdivision, to break that surface into a set of all quadrilateral patches. (2) for each such quadrilateral patch, we construct a Bi-Cubic Bezier patch, where the positions of the 16 control points are obtained from the limit surface of the Doo–Sabin subdivision scheme. This approach, when combined with topological modeling, provides a framework for real-time interactive modeling of smooth manifold meshes with arbitrary topology. Based on this approach, we have developed an interactive modeling system that allows users to work with smooth surfaces in real-time by opening or closing holes, creating handles, and combining and disconnecting surfaces. The paper has three main contributions: (1) We guarantee that our method will produce only smooth manifold meshes with C 2 continuous Bi-Cubic Bezier patches. (2) We guarantee visual smoothness for any arbitrary topological structure by providing geometric G 1 continuity in boundaries of patches. (3) We demonstrate that smooth surfaces with arbitrary topology can be created interactively in real-time using parametric patches.
- Published
- 2017
40. Art-directed watercolor stylization of 3D animations in real-time
- Author
-
Santiago E. Montesdeoca, Hock Soon Seah, Hans-Martin Rall, Davide Benvenuti, and Interdisciplinary Graduate School (IGS)
- Subjects
NPR ,business.industry ,Computer science ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,02 engineering and technology ,Animation ,Computer Graphics and Computer-Aided Design ,GeneralLiterature_MISCELLANEOUS ,Rendering (computer graphics) ,Human-Computer Interaction ,Hand tremor ,Computer graphics (images) ,0202 electrical engineering, electronic engineering, information engineering ,Color bleeding ,Watercolor ,020201 artificial intelligence & image processing ,Computer vision ,Artificial intelligence ,business ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
This paper presents a direct stylization system to render 3D animated geometry as watercolor painted animation. Featuring low-level art-direction in real-time, our approach focuses on letting users paint custom stylization parameters in the 3D scene. These painted parameters drive watercolor effects in object-space, managing localized control and emulating the characteristic appearance of traditional watercolor. For this purpose, the parameters alter the object-space geometric representations and are rasterized, to coherently control and enhance further image-space effects. The watercolor effects are simulated through improved and novel algorithms to recreate hand tremors, pigment turbulence, color bleeding, edge darkening, paper distortion and granulation. All these represent essential characteristic effects of traditional watercolor. The proposed direct stylization system scales well with scene complexity, can be implemented in most rendering pipelines and can be adapted to simulate a wide range of watercolor looks. The simulation is compared to previous approaches and is evaluated through a user study, involving professional CG artists spending over 50 h stylizing their own assets and sharing their feedback about the watercolor stylization, the direct stylization system and their needs as artists using Non-photorealistic Rendering (NPR). Accepted version
- Published
- 2017
41. Falcon: Visual analysis of large, irregularly sampled, and multivariate time series data in additive manufacturing
- Author
-
William Halsey, Sean Yoder, Vincent C. Paquit, Ryan R. Dehoff, Chad A. Steed, and Sarah Powers
- Subjects
0209 industrial biotechnology ,Visual analytics ,business.industry ,Computer science ,General Engineering ,020207 software engineering ,02 engineering and technology ,Machine learning ,computer.software_genre ,Computer Graphics and Computer-Aided Design ,Field (computer science) ,Human-Computer Interaction ,Exploratory data analysis ,Information visualization ,020901 industrial engineering & automation ,Knowledge extraction ,0202 electrical engineering, electronic engineering, information engineering ,Data mining ,Artificial intelligence ,Time series ,business ,Scale (map) ,Focus (optics) ,computer - Abstract
Flexible visual analysis of long, high-resolution, and irregularly sampled time series data from multiple sensor streams is a challenge in several domains. In the field of additive manufacturing, this capability is critical for realizing the full potential of large-scale 3D printers. In this paper, we propose a visual analytics approach that helps additive manufacturing researchers acquire a deep understanding of patterns in log and imagery data collected by 3D printers. Specific goals include discovering patterns related to defects and system performance issues, optimizing build configurations to avoid defects, and increasing production efficiency. We introduce Falcon, a new visual analytics system that allows users to interactively explore large, time-oriented data sets from multiple linked perspectives. Falcon provides overviews, detailed views, and unique segmented time series visualizations, all with adjustable scale options. To illustrate the effectiveness of Falcon at providing thorough and efficient knowledge discovery, we present a practical case study involving experts in additive manufacturing and data from a large-scale 3D printer. Although the focus of this paper is on additive manufacturing, the techniques described are applicable to the analysis of any quantitative time series.
- Published
- 2017
42. Star-effect simulation for photography
- Author
-
Dongwei Liu, Tieying Liu, Haokun Geng, and Reinhard Klette
- Subjects
business.industry ,Computer science ,Photography ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,Stereo matching ,020207 software engineering ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Luminance ,Rendering (computer graphics) ,Human-Computer Interaction ,Stereopsis ,Mobile phone ,Stereo image ,Computer graphics (images) ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Computer vision ,Artificial intelligence ,business ,Star pattern ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
This paper discusses the creation of star effects in captured night-time photos based on using depth information available by stereo vision. Star effects are an important design factor for night-time photos. Modern imaging technologies support that night-time photos can be taken free-hand, but star effects are not achievable for such camera settings. Self-calibration is an important feature of the presented star-effect simulation method. A photographer is assumed to take just an uncalibrated stereo image pair (i.e. a base and a match image), for example by taking two photos subsequently (e.g. by a mobile phone at about the same pose). For self-calibration we apply the following routine: extract a family of pairs of feature points, calibrate the stereo image pair by using those feature points, and calculate depth data by stereo matching. For creating the star effects, first we detect highlight regions in the base image. Second, we estimate the luminance according to available depth information. Third, we render star patterns with a chosen input texture. Basically we provide a complete tool which is easy to apply for the generation of a user-selected star texture. Minor variations can be introduced in star pattern rendering in order to achieve more natural and vivid looking star effects. By extensive experiments we verified that our rendering results are potentially similar to real-world star effect photos. We demonstrate some of our results, also for illustrating that they appear more natural than results achieved by existing commercial applications. We also illustrate that our method allows us to render more artistic star patterns not available in recorded photographs. In brief, this paper reports research on automatically simulating both photorealistic and non-photorealistic star effects.
- Published
- 2016
43. Deep weathering effects
- Author
-
Adrien Verhulst, Jean-Marie Normand, Guillaume Moreau, Gustavo Patow, École Centrale de Nantes (Nantes Univ - ECN), Nantes Université (Nantes Univ), Centre de recherche nantais Architectures Urbanités (CRENAU ), Ambiances, Architectures, Urbanités (AAU), Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Grenoble (ENSAG ), Université Grenoble Alpes (UGA)-Université Grenoble Alpes (UGA)-École Centrale de Nantes (Nantes Univ - ECN), Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-NANTES UNIVERSITÉ - École nationale supérieure d'architecture de Nantes (Nantes Univ - ENSA Nantes), Nantes Université (Nantes Univ)-Ministère de la Culture et de la Communication (MCC)-Centre National de la Recherche Scientifique (CNRS)-École nationale supérieure d'architecture de Grenoble (ENSAG ), 3D interaction with virtual environments using body and mind (Hybrid), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-RÉALITÉ VIRTUELLE, HUMAINS VIRTUELS, INTERACTIONS ET ROBOTIQUE (IRISA-D5), Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut de Recherche en Informatique et Systèmes Aléatoires (IRISA), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Bretagne Sud (UBS)-École normale supérieure - Rennes (ENS Rennes)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Equipe Immersive Natural User Interaction team (Lab-STICC_INUIT), Laboratoire des sciences et techniques de l'information, de la communication et de la connaissance (Lab-STICC), École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS)-Université Bretagne Loire (UBL)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT), IMT Atlantique (IMT Atlantique), Universitat de Girona (UdG), and Adrien Verhulst was supported by a joint research grant from the École Centrale de Nantes, France, and Audencia Busi- ness School, France. This work was also partially funded by Grant PID2021-122136OB-C22 funded by MCIN/AEI/10.13039/ 501100011033 and by ERDF A way of making Europe.
- Subjects
Human-Computer Interaction ,Rust ,Weathering ,Bricks ,Iron ,General Engineering ,Computer Graphics and Computer-Aided Design ,[INFO.INFO-GR]Computer Science [cs]/Graphics [cs.GR] - Abstract
International audience; Weathering phenomena are ubiquitous in urban environments, where it is easy to observe severely degraded old buildings as a result of water penetration. Despite being an important part of any realistic city, this kind of phenomenon has received little attention from the Computer Graphics community compared to stains resulting from biological or flow effects on the building exteriors. In this paper, we present physically-inspired deep weathering effects, where the penetration of humidity (i.e., water particles) and its interaction with a building's internal structural elements result in large, visible degradation effects. Our implementation is based on a particle-based propagation model for humidity propagation, coupled with a spring-based interaction simulation that allows chemical interactions, like the formation of rust, to deform and destroy a building's inner structure. To illustrate our methodology, we show a collection of deep degradation effects applied to urban models involving the creation of rust or of ice within walls.
- Published
- 2023
44. Learning to segment and unfold polyhedral mesh from failures
- Author
-
Young J. Kim, Jyh-Ming Lien, Zhonghua Xi, and Yun-hyeong Kim
- Subjects
Computer science ,General Engineering ,020207 software engineering ,Ranging ,Polyhedral mesh ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Convexity ,Flattening ,Human-Computer Interaction ,Planar ,TheoryofComputation_LOGICSANDMEANINGSOFPROGRAMS ,0202 electrical engineering, electronic engineering, information engineering ,Preprocessor ,020201 artificial intelligence & image processing ,Segmentation ,Algorithm ,ComputingMethodologies_COMPUTERGRAPHICS ,Shape analysis (digital geometry) - Abstract
Folding planar sheets to make 3D shapes from is an ancient practice with many new applications, ranging from personal fabrication of customized items to design of surgical instruments for minimally invasive surgery in self-folding machines. Given a polyhedral mesh, unfolding is an operation of cutting and flattening the mesh. The flattened polyhedral nets are then cut out of planar materials and folded back to 3D. Unfolding a polyhedral mesh into planar nets usually require segmentation. Either used as a preprocessing step to simplify the mesh and provide semantics or as the result of unfolding to avoid overlapping, the segmentation and the unfolding operations are decoupled. Consequently, segmented components may not be unfoldable and unfolded nets usually provide no semantic meaning and make folding difficult. In this paper, we propose a strategy that tightly couples unfolding and segmentation. We show that the proposed method produces unfoldable segmentation that resembles carefully designed paper craft. The key idea that enables this capability is an algorithm that learns from failed unfoldings. Graphical abstractDisplay Omitted HighlightsWe propose a strategy that produces unfoldable segmentation via failed unfoldings.Our unfoldable segmentation provides shape semantics and convexity.Shape semantics in the proposed segmentation eases the fabrication process.High convexity allows higher proability of finding collision-free folding path.Collision-free folding path is critical in developing a self-folding machine.
- Published
- 2016
45. Shape context based mesh saliency detection and its applications: A survey
- Author
-
Ligang Liu, Lizhuang Ma, Yanping Liu, Weijie Song, and Xianyong Liu
- Subjects
Geometric analysis ,Computer science ,business.industry ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,Image processing ,Volume rendering ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Computer graphics ,Pattern recognition (psychology) ,0202 electrical engineering, electronic engineering, information engineering ,Robot ,020201 artificial intelligence & image processing ,Segmentation ,Computer vision ,Shape context ,Artificial intelligence ,business ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
Mesh saliency was introduced and joined the community of computer graphics ten years ago, which can benefit various applications, for instance, mesh reduction, mesh segmentation, self-similarity matching, scan integration, volume rendering, 3D printing, etc. Before, saliency detection had been successfully applied to image processing and pattern recognition to study how the world is perceptually intelligible for robots. In contrast to color of images and coherence of videos, geometric signals are defined with two-dimensional manifolds whose discrete representation is irregular, leading differences to the nature and difficulties to the solution of mesh saliency. To tackle the challenge, the last decade has witnessed significant advances in mesh saliency detection. However, a survey of recent advances in mesh saliency detection as well as its applications does not yet exist to date. This paper provides a first and comprehensive reference source of shape context based mesh saliency for researchers from a wide range of domains, including but not limited to computer graphics and vision. It reviews main contributions, advantages, drawbacks, and applications of known mesh saliency detection methods and discusses current trends and outlook for future study. Graphical abstractDisplay Omitted HighlightsThe paper provides the first and comprehensive reference resource of mesh saliency.35 representative methods published from 2005 to 2015 are viewed.4 key insights into the topic are presented, and open problems are raised.
- Published
- 2016
46. Tracking for mobile devices: A systematic mapping study
- Author
-
Veronica Teichrieb, João Paulo Lima, and Rafael Roberto
- Subjects
Computer science ,General Engineering ,020206 networking & telecommunications ,020207 software engineering ,02 engineering and technology ,computer.software_genre ,Computer Graphics and Computer-Aided Design ,Human-Computer Interaction ,Navigation assistance ,Schema (psychology) ,0202 electrical engineering, electronic engineering, information engineering ,Augmented reality ,Data mining ,Systematic mapping ,Web crawler ,Mobile device ,computer - Abstract
Tracking is an important task that is used for several applications, such as navigation assistance and augmented reality. The improvement and popularization of mobile devices in recent years allowed these applications to be executed on such devices. Thus, several tracking techniques proposed lately take into consideration the benefits and limitations of handheld devices. Therefore, the goal of this work is to perform a systematic mapping in order to provide trends and classification regarding the recent publications in the area of tracking for mobile devices. This study collected 2276 papers from three scientific databases using an open-source crawler, from which 360 were selected to be classified according to four properties: tracking type, degree of freedom, tracking platform and research type. The analysis of these data resulted in a map of the research field, which was presented under three perspectives: the distribution and trends over time of each classification property and the relationship between them. Besides the visual map, the full list of classified papers is available through an open-source web-based catalog. The results showed that the number of publications is increasing every year, which shows a growing interest in this field. Moreover, most works use the device's sensors for tracking in location-based applications and almost all of them calculate a 2D or 2D + ? pose. There are also several papers about vision-based techniques to compute the device's pose and in the majority of them a full 6D pose is computed. Beyond that, there is a clear preference for systems that calculate the pose locally on the device and only a few use a remote server to assist in this task. Moreover, more than 92% of all papers propose a new technique or use existing ones to create a solution. Graphical abstractDisplay Omitted HighlightsIdentification of the relevant studies in tracking for mobile devices.Classification schema of the field.Systematic map of the existing research in the area.Discussion about the major findings of this study.Web application with a catalog of classified studies that is collaboratively updated.
- Published
- 2016
47. Creating light atlases with multi-bounce indirect illumination
- Author
-
Marc Stamminger, Randolf Schärfig, and Kai Hormann
- Subjects
Point light ,Texture atlas ,Photon mapping ,Computer science ,business.industry ,Global illumination ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,020207 software engineering ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,Rendering (computer graphics) ,Progressive refinement ,Human-Computer Interaction ,Computer graphics (images) ,0202 electrical engineering, electronic engineering, information engineering ,Projection method ,020201 artificial intelligence & image processing ,Computer vision ,Artificial intelligence ,Graphics ,business ,ComputingMethodologies_COMPUTERGRAPHICS - Abstract
Indirect illumination is an essential part of realistically rendering virtual scenes. In this paper we present a new method for computing multi-bounce indirect illumination for diffuse surfaces which is particularly well-suited for indoor scenes with complex occlusion, where an appropriate simulation of the indirect illumination is extremely important. The technique presented in this paper combines the benefits of shooting methods with the concept of photon mapping to compute a convincing light map for the scene with full diffuse lighting effects. The main idea is to carry out a multi-bounce light distribution almost entirely on the GPU using a shooting approach with virtual point lights. The final result is then stored in a texture atlas by projecting the energy from each virtual point light into the texels visible from its perspective. The technique uses only few resources on the graphics card and is flexible in the sense that it can easily be adjusted for either quality or speed, allowing the user to create convincing results in a matter of seconds or minutes, depending on the scene complexity. Graphical abstractDisplay Omitted HighlightsApproximating a physically correct light distribution with multiple bounces.Developing a progressive refinement algorithm for virtual point lights on the GPU.Creating a high-resolution light atlas with a special projection method on the GPU.
- Published
- 2016
48. Depth of field synthesis from sparse views
- Author
-
Jon G. Rokne and Xin Liu
- Subjects
Pixel ,Aperture ,Computer science ,business.industry ,Computer-generated imagery ,Visibility (geometry) ,General Engineering ,020207 software engineering ,02 engineering and technology ,Computer Graphics and Computer-Aided Design ,law.invention ,Human-Computer Interaction ,Lens (optics) ,law ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Pinhole (optics) ,Computer vision ,Depth of field ,Artificial intelligence ,business ,Distributed ray tracing - Abstract
Computer generated images are most easily generated as pinhole images whereas images obtained with optical lenses exhibit a Depth-of-Field (DOF) effect. This is due to the fact that optical lenses gather light across finite apertures whereas the simulation of a pinhole lens means that the light is gathered through an infinitesimal small aperture, thus producing sharp images at any depth. Simulating the physical process of gathering light across a finite aperture can be done for example with distributed ray tracing, but it is computationally much more expensive than the simulation through an infinitesimal aperture. The usual way of simulating lens effects is therefore to produce a pinhole image and then post processes the image to approximate the DOF. Post processing algorithms are fast but suffer from incorrect visibilities. In this paper, we propose a novel algorithm that tackles the visibility issue with a sparse set of views rendered through the optical center of the lens and several peripheral viewpoints distributed on the lens. All peripheral images are warped towards the central view to create a Layered-Depth-Image (LDI), so that all observed 3D points located on the same central view-ray are stacked on the same pixel of the LDI. Then, each pixel in the LDI is conceptually scattered into a Point-Spread-Function (PSF) and blended in depth order. While the scatter method is very inefficient on a GPU, we propose a selective-gather method for DOF synthesis, which scans the neighborhood of a pixel and blends the colors from the PSFs covering the pixel. Experiments show that the proposed algorithm can synthesize high-quality DOF effects close to the results of distributed ray tracing but at a much higher speed. Display Omitted HighlightsThe paper discusses a fast algorithm for DOF simulation from a sparse set of pinhole images.The algorithm provides simulations of DOF effects close to those produced by distributed ray tracing but at a significantly lower cost.
- Published
- 2016
49. Focus plus context visualization based on volume clipping for markerless on-patient medical data visualization
- Author
-
Antônio L. Apolinário and Márcio C. F. Macedo
- Subjects
Focus (computing) ,Visual perception ,Computer science ,Image quality ,business.industry ,General Engineering ,Context (language use) ,Computer Graphics and Computer-Aided Design ,Visualization ,Human-Computer Interaction ,Data visualization ,Computer graphics (images) ,Computer vision ,Augmented reality ,Artificial intelligence ,Clipping (computer graphics) ,business - Abstract
Focus plus context visualization can be used in augmented reality to improve the visual perception of the augmented scene. In the scope of in situ or on-patient medical data visualization, the focus plus context paradigm is used to improve depth perception for physicians showing the patient's anatomy as a focus region in the context of the patient's body. Volume clipping is one technique to realize focus plus context visualization. However, some of the existing methods for focus plus context visualization based on volume clipping do not run in full real time or are prone to artifacts. In this paper, we present an extension for two of these techniques to improve performance and image quality of the original approaches. We validate all the techniques in a markerless augmented reality environment. A 3D reference model is tracked by the application, and volumetric medical data are shown to the user at the position of the patient's anatomy. Our technique is able to handle multiple anatomic regions, although the main region of interest used in this paper is the face. Moreover, tracking accuracy is improved by the use of a hierarchical approach. From an evaluation of the proposed techniques, the results obtained highlight that all of them are free of artifacts, optimized for real-time performance, and improve the visual quality of the augmented scene. Graphical abstractDisplay Omitted HighlightsImprovement of smooth contours technique to achieve real-time performance.Improvement of visible background on MRI data to achieve higher visual quality.Use of a hierarchical ICP algorithm to improve tracking accuracy.Extension of the on-patient visualization for different parts of the patient's body.
- Published
- 2015
50. Computer graphics 'Made in Germany'
- Author
-
Dieter W. Fellner and José L. Encarnação
- Subjects
Knowledge society ,Multimedia ,Institutional development ,Computer science ,General Engineering ,Scientific visualization ,computer.software_genre ,Computer Graphics and Computer-Aided Design ,Visual computing ,Human-Computer Interaction ,Computer graphics ,Computer graphics (images) ,Technological impact ,computer - Abstract
The paper reports on the 40 years of development of Computer Graphics and, more recently, Visual computing (VC) at the Technische Universitat Darmstadt in Germany, from its beginning in 1975 to the leading “Computer Graphics and Visual Computing Hub” in Europe as of 2014. This development is described along three axes. First, the institutional development and its rational to establish Computer Graphics as a discipline of Computer Science and as an enabling technology for developing our Knowledge Society, are described. Second, the scientific and technological impact based on the teaching activities and the large number of theses submitted in Darmstadt for the area during these 40 years are addressed. Finally, the research road maps of the Computer Graphics and Visual Computing Hub in Darmstadt are presented relatively to the different stages of CG and VC research, relatively to a scientific view to the large number of projects implemented over these 40 years and, finally, also relatively to the project results as seen from the media. In order to manage the quantity as well as the complexity of the information available, the description of these road maps is divided in four time periods: 1975–1984, 1985–1994, 1995–2004 and 2004–2015. The paper also gives the view of the authors on how they see the future of Computer Graphics and Visual Computing. At the end, the paper includes an extensive list of references for the reported content.
- Published
- 2015
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.