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prof. Ing. Jiří Žára, CSc.

Všechny publikace

Moon Base: A Serious Game for Education

  • DOI: 10.1109/VS-Games.2019.8864540
  • Odkaz: https://doi.org/10.1109/VS-Games.2019.8864540
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    To increase the interest of young people in the technological and scientific aspects of space research, the European Space Education Resources Office (ESERO) has decided to develop a set of games with space themes. Our group was selected to design and implement a game in virtual reality. In this paper, we describe the main design principles, interaction and navigation techniques, and technological details of the final game titled Moon Base.

On Improving 3D U-net Architecture

  • DOI: 10.5220/0007830306490656
  • Odkaz: https://doi.org/10.5220/0007830306490656
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    This paper presents a review of various techniques for improving the performance of neural networks on segmentation task using 3D convolutions and voxel grids – we provide comparison of network with and without max pooling, weighting, masking out the segmentation results, and oversampling results for imbalanced training dataset. We also present changes to 3D U-net architecture that give better results than the standard implementation. Although there are many out-performing architectures using different data input, we show, that although the voxel grids that serve as an input to the 3D U-net, have limits to what they can express, they do not reach their full potential.

Distinctive Approaches to Computer Graphics Education

  • DOI: 10.1111/cgf.13305
  • Odkaz: https://doi.org/10.1111/cgf.13305
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    This paper presents the latest advances and research in Computer Graphics education in a nutshell. It is concerned with topics that were presented at the Education Track of the Eurographics Conference held in Lisbon in 2016. We describe works corresponding to approaches to Computer Graphics education that are unconventional in some way and attempt to tackle unsolved problems and challenges regarding the role of arts in computer graphics education, the role of research-oriented activities in undergraduate education and the interaction among different areas of Computer Graphics, as well as their application to courses or extra-curricular activities. We present related works addressing these topics and report experiences, successes and issues in implementing the approaches.

A Trip to Arts for Computer Graphics Students

  • DOI: 10.2312/eged.20161019
  • Odkaz: https://doi.org/10.2312/eged.20161019
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Complex and sophisticated projects, on which information technologists and artists meet and cooperate, often require an understanding of possible problems and solutions seen from both sides. While artists (creators) are usually somewhat familiar with current technologies, e.g. the Computer Graphics (CG) field, programmers are not well educated in the arts and their understanding of artistic needs is thus insufficient. In order to improve the education of CG students towards fine arts, we have created a BSc course on Art and Graphics design and have been running it for seven years. We consider this approach to education at a technologically oriented university as unusual and rare, but highly valuable for CG students. This paper describes the content of the course, summarizes the experience gained, and evaluates its usefulness for CG students in the subsequent MSc study program.

Remote operation of the GOLEM tokamak for Fusion Education

  • Autoři: Grover, O., Kocman, J., Odstrcil, M., Odstrcil, T., Svoboda, V., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Fusion Engineering and Design. 2016, 112 1038-1044. ISSN 0920-3796.
  • Rok: 2016
  • DOI: 10.1016/j.fusengdes.2016.05.009
  • Odkaz: https://doi.org/10.1016/j.fusengdes.2016.05.009
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Practically oriented education in the field of thermonuclear fusion is highly requested, However, the high complexity of appropriate experiments makes it difficult to develop and maintain laboratories where students can take part in hands-on experiments in this field of study. One possible solution is to establish centres with specific high temperature plasma experiments where students can visit such a laboratory and perform their experiments in-situ. With the advancements of IT technologies it naturally follows to make a step forward and connect these with necessary plasma physics technologies and thus allow to access even sophisticated experiments remotely. Tokamak GOLEM is a small, modest device with its infrastructure linked to web technologies allowing students to set-up necessary discharge parameters, submit them into a queue and within minutes obtain the results in the form of a discharge homepage. (C) 2016 Elsevier B.V. All rights reserved.

Stateless generation of distributed virtual worlds

  • DOI: 10.1016/j.cag.2014.07.002
  • Odkaz: https://doi.org/10.1016/j.cag.2014.07.002
  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    We present novel techniques for implementing possibly infinite on-demand generated 3D virtual worlds in distributed environments. Our approach can be useful in two scenarios: 1. A multiuser virtual world with mobile clients with sufficient CPU and GPU power but with limited network speed. This reflects current mobile phones, tablets and laptops in areas without a high-speed mobile connection or Wi-Fi connectivity. 2. Virtual world on-demand generation in a cloud environment that would be useful for scalable massive multiplayer games. If multiple independent generators create areas that are overlapping, our method ensures that the intersection of the areas will contain the same geometry for all of them. For this reason, we call our method stateless generation.

3D Reconstruction Data Set - The Langweil Model of Prague

  • DOI: 10.1260/2047-4970.2.2.195
  • Odkaz: https://doi.org/10.1260/2047-4970.2.2.195
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    A large data set of input RAW photos for 3D reconstruction of historical paper model of Prague is presented in this paper. The data acquisition process and its organisation are described in detail together with color and camera calibration algorithms used. Moreover, a complete reconstruction work-flow together with several cultural heritage applications are briefly presented. The subject of this 3D reconstruction has been the Langweil model of Prague, originally created in the first half of 19th century. Three parts of this model with different characteristics are afforded for computer scientists through the internet.

DCGI Laboratories at CTU Prague, Czech Republic

  • DOI: 10.2312/conf/EG2013/lab/L04
  • Odkaz: https://doi.org/10.2312/conf/EG2013/lab/L04
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    The Department of Computer Graphics and Interaction (DCGI) covers education and research activities in Computer Graphics and HumanComputer Interaction areas at the Czech Technical University in Prague (CTU). This paper presents the staff, laboratories, projects, and selected scientific achievements of the DCGI.

3D Talking-Head Interface to Voice-Interactive Services on Mobile Phones

  • Autoři: Danihelka, J., Dr. Mgr. Lukáš Kencl, Hák, R., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Developments in Technologies for Human-Centric Mobile Computing and Applications. Hershey, Pennsylvania: IGI Global, 2012. p. 130-144. ISBN 9781466620681.
  • Rok: 2012
  • DOI: 10.4018/978-1-4666-2068-1.ch008
  • Odkaz: https://doi.org/10.4018/978-1-4666-2068-1.ch008
  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    This paper presents a novel framework for easy creation of interactive, platform-independent voice-services with an animated 3D talking-head interface, on mobile phones. The Framework supports automated multi-modal interaction using speech and 3D graphics. The difficulty of synchronizing the audio stream to the animation is examined and alternatives for distributed network control of the animation and application logic is discussed. The ability of modern mobile devices to handle such applications is documented and it is shown that the power consumption trade-off of rendering on the mobile phone versus streaming from the server favors the phone. The presented tools will empower developers and researchers in future research and usability studies in the area of mobile talking-head applications (Figure 1). These may be used for example in entertainment, commerce, health care or education.

Multi-user Immersive 3D Reconstruction Environment

User Driven 3D Reconstruction Environment

  • Autoři: Ing. David Sedláček, Ph.D., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Advances in Visual Computing, 8th International Symposium, ISVC 2012, Rethymnon, Crete, Greece, July 16-18, 2012, Revised Selected Papers, Part I. Berlin: Springer-Verlag, 2012. pp. 104-114. Lecture Notes in Computer Science. ISSN 0302-9743. ISBN 978-3-642-33179-4.
  • Rok: 2012
  • DOI: 10.1007/978-3-642-33179-4_11
  • Odkaz: https://doi.org/10.1007/978-3-642-33179-4_11
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    An intuitive image-based 3D reconstruction tool based on inaccurate user strokes is presented in this paper. The combination of fast image segmentation method together with user knowledge about reconstructed scene forms a novel low-polygonal editor suitable for architecture reconstruction. The user interaction is minimized thanks to propagation of strokes among input photographs. The final model geometry is created by innovative algorithm. The input to the tool is a set of calibrated photographs together with a sparse pointcloud. The output is a structured low-poly 3D model.

3D Talking-Head Interface to Voice-Interactive Services on Mobile Phones

  • DOI: 10.4018/jmhci.2011040104
  • Odkaz: https://doi.org/10.4018/jmhci.2011040104
  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    This paper presents a novel framework for easy creation of interactive, platform-independent voice-services with an animated 3D talking-head interface, on mobile phones. The Framework supports automated multi-modal interaction using speech and 3D graphics. The difficulty of synchronizing the audio stream to the animation is examined and alternatives for distributed network control of the animation and application logic is discussed. The ability of modern mobile devices to handle such applications is documented and it is shown that the power consumption trade-off of rendering on the mobile phone versus streaming from the server favors the phone. The presented tools will empower developers and researchers in future research and usability studies in the area of mobile talking-head applications (Figure 1). These may be used for example in entertainment, commerce, health care or education.

Architectural Styles Dependent Shape Grammar Representation of Facades

  • Autoři: Dušková, E., prof. Ing. Jiří Žára, CSc.,
  • Publikace: EG 2011 - Posters. Aire-la-Ville: Eurographics Association, 2011. pp. 1-2. ISSN 1017-4656.
  • Rok: 2011
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    In this poster, we present an idea to utilize formal rules and descriptions for architectural styles from various time periods. We focus on facades of historical buildings with identical purpose located in a specific geographical area. We have chosen the CGA shape grammar as a formal language to represent and visualise the rules and we demonstrate our approach on facades of the residence-type historical buildings located in Prague. Our aim is to show that differences in formal descriptions of various buildings are tightly related to differences in architectural styles. Having a proper metrics for such CGA grammars, we will be able to generate new virtual buildings of certain architectural style and to control their possible transitions among distinct styles.

Interactive Modeling and Visualization of Virtual Urban Spaces

  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    focused on procedural techniques like L systems or shape grammars and their usability in procedural architecture creation. Then, we introduce essential articles on procedural modelling of cities and we also include ideas from papers specialized in generation of buildings, facades, architectural structures and related city components. Finally, we focus on interesting computer vision techniques in architecture reconstruction and their connection to formal languages. Our aim is to demonstrate that the procedural city modelling needs to integrate specially modified computer vision algorithms in order to achieve a higher degree of realism and a wider acceptance in various professional application areas.

Procedural Generation of Infinite Cities

  • Autoři: Danihelka, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: EG 2011 - Posters. Aire-la-Ville: Eurographics Association, 2011. pp. 31-33. ISSN 1017-4656.
  • Rok: 2011
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    We present a novel technique for generation of pseudo-random infinite cities in a real-time. The generated cities can have arbitrarily oriented streets and building blocks can be arbitrarily shaped. The shapes of city buildings are determined using a pseudo-random generator that uses building coordinates as the initial generator seed.

The GOLEM Tokamak for Fusion Education

  • Autoři: Svoboda, V., Bromová, E., Ďuran, I., Grover, O., Kocman, J., Markovič, T., Odstrčil, T., Odstrčil, M., Pluhař, O., Stöckel, J., Šindlery, A., Vondrášek, G., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Europhysics Conference Abstracts. 38th EPS Conference on Plasma Physics. Mulhouse: European Physical Society, 2011. 35G. ISBN 978-1-61839-593-1.
  • Rok: 2011
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    The GOLEM tokamak, (formerly CASTOR), became an educational device for domestic as well as for foreign students via remote participation/handling. It operates routinely for nearly two years at modest range of parameters and with a limited set of diagnostics. Wide range of tasks with varying levels of complexity covering tokamak physics, technology and operation can be studied by the future fusion specialists. Currently the diagnostics enrichment is strategic for the education usability of the device. Students participate in large extent on additional standard diagnostics methods development, including density measurement via microwave interferometry, plasma position (including tomography) studies using a set of Mirnov coils, two fast cameras and two linear arrays of bolometers. Moreover stabilization of the plasma position with an equilibrium magnetic field generated in the vertical magnetic field coils and plasma spectroscopy issues are under consideration.

The Langweil Model of Prague - a Challenge for State-of-the-art 3D Reconstruction Techniques

  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    The challenges for current state-of-the-art 3D reconstruction algorithms covered in the Langweil model of Prague data set are summarized in this poster. The model properties are presented together with problems which bring.

3D Talking-Head Interface to Voice-Interactive Services on Mobile Phones

  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    We present a novel framework for easy creation of interactive, platform-independent voice-services with an animated 3D talking-head interface, on mobile phones. The framework supports automated multi-modal interaction using speech and 3D graphics. We address the difficulty of synchronizing the audio stream to the animation and discuss alternatives for distributed network control of the animation and application logic. We document the ability of modern mobile devices to handle such applications and show that the power consumption trade-off of rendering on the mobile phone versus streaming from the server favors the phone.

Reduction of Animated Models for Embedded Devices

  • Pracoviště: Katedra telekomunikační techniky, Katedra počítačové grafiky a interakce
  • Anotace:
    We present a new supplementary method for reduction of animated 3D polygonal models. The method is applicable mainly in animation of human faces and it is based on intelligent merging of visemes represented by key polygonal meshes. It is useful for devices with limited CPU and memory resources like mobile phones or other embedded devices. Using this approach we can reduce operation memory needs and time to load the model from storage. We describe the algorithm for viseme merging and we prove that our method is optimal for selected metrics. Finally we validate method performance on an example and compare with the case when only traditional methods for 3D models reduction are used.

Cultural Heritage, User Interfaces and Serious Games at CTU Prague

  • DOI: 10.1109/VSMM.2009.38
  • Odkaz: https://doi.org/10.1109/VSMM.2009.38
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Cultural heritage presentation is a topic we at CTU Prague deal with more than ten years. In this paper we present our experience with user interface design where serious games paradigm has been utilized. The survey of selected projects represents various technologies and approaches for cultural heritage data handling that includes data acquisition, presentation, interaction and educational issues. The aim of our activities was to develop a systematic approach to the user interface design for the given class of applications.

Graph Cut Based Point-Cloud Segmentation for Polygonal Reconstruction

  • DOI: 10.1007/978-3-642-10520-3_20
  • Odkaz: https://doi.org/10.1007/978-3-642-10520-3_20
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    The reconstruction of 3D objects from a point-cloud is based on sufficient separation of the points representing objects of interest from the points of other, unwanted objects. This operation called segmentation is discussed in this paper. We present an interactive unstructured point-cloud segmentation based on graph cut method where the cost function is derived from euclidean distance of point-cloud points. The graph topology and direct 3D point-cloud segmentation are the novel parts of our work. The segmentation is presented on real application, the terrain reconstruction of a complex miniature paper model, the Langweil model of Prague.

Geometric skinning with approximate dual quaternion blending

  • Autoři: Kavan, L., Collins, S., prof. Ing. Jiří Žára, CSc., O'Sullivan, C.
  • Publikace: ACM Transactions on Graphics (TOG). 2008, 27(4), 1-23. ISSN 0730-0301.
  • Rok: 2008
  • DOI: 10.1145/1409625.1409627
  • Odkaz: https://doi.org/10.1145/1409625.1409627
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Skinning of skeletally deformable models is extensively used for real-time animation of characters, creatures and similar objects. The standard solution, linear blend skinning, has some serious drawbacks that require artist intervention. Therefore, a number of alternatives have been proposed in recent years. All of them successfully combat some of the artifacts, but none challenge the simplicity and efficiency of linear blend skinning. As a result, linear blend skinning is still the number one choice for the majority of developers. In this article, we present a novel skinning algorithm based on linear combination of dual quaternions. Even though our proposed method is approximate, it does not exhibit any of the artifacts inherent in previous methods and still permits an efficient GPU implementation. Upgrading an existing animation system from linear to dual quaternion skinning is very easy and has a relatively minor impact on runtime performance.

Polypostors: 2D polygonal impostors for 3D crowds

  • Autoři: Kavan, L., Dobbyn, S., Collins, S., prof. Ing. Jiří Žára, CSc., O'Sullivan, C.
  • Publikace: Proceedings of the 2008 symposium on Interactive 3D graphics and games. New York: ACM SIGGRAPH, 2008. p. 149-155. ISBN 978-1-59593-983-8.
  • Rok: 2008
  • DOI: 10.1145/1342250.1342273
  • Odkaz: https://doi.org/10.1145/1342250.1342273
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Various methods have been proposed to animate and render large crowds of humans in real time for applications such as games and interactive walkthroughs. This paper proposes an alternative method that significantly improves upon pre-computed impostors: automatically generated 2D polygonal characters (or Polypostors).

Skinning arbitrary deformations

  • Autoři: Kavan, L., McDonnell, R., Dobbyn, S., prof. Ing. Jiří Žára, CSc., O'Sullivan, C.
  • Publikace: Proceedings of the 2007 symposium on Interactive 3D graphics and games. New York: ACM SIGGRAPH, 2007. p. 53-60. ISBN 978-1-59593-628-8.
  • Rok: 2007
  • DOI: 10.1145/1230100.1230109
  • Odkaz: https://doi.org/10.1145/1230100.1230109
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Matrix palette skinning (also known as skeletal subspace deformation) is a very popular real-time animation technique. So far, it has only been applied to the class of quasi-articulated objects, such as moving human or animal figures. In this paper, we demonstrate how to automatically construct skinning approximations of arbitrary precomputed animations, such as those of cloth or elastic materials. In contrast to previous approaches, our method is particularly well suited to input animations without rigid components. Our transformation fitting algorithm finds optimal skinning transformations (in a least-squares sense) and therefore achieves considerably higher accuracy for non-quasi-articulated objects than previous methods. This allows the advantages of skinned animations (e.g., efficient rendering, rest-pose editing and fast collision detection) to be exploited for arbitrary deformations.

Skinning with dual quaternions

  • Autoři: Kavan, L., Collins, S., prof. Ing. Jiří Žára, CSc., O'Sullivan, C.
  • Publikace: Proceedings of the 2007 symposium on Interactive 3D graphics and games. New York: ACM SIGGRAPH, 2007. p. 39-46. ISBN 978-1-59593-628-8.
  • Rok: 2007
  • DOI: 10.1145/1230100.1230107
  • Odkaz: https://doi.org/10.1145/1230100.1230107
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Skinning of skeletally deformable models is extensively used for real-time animation of characters, creatures and similar objects. The standard solution, linear blend skinning, has some serious drawbacks that require artist intervention. Therefore, a number of alternatives have been proposed in recent years. All of them successfully combat some of the artifacts, but none challenge the simplicity and efficiency of linear blend skinning. As a result, linear blend skinning is still the number one choice for the majority of developers. In this paper, we present a novel GPU-friendly skinning algorithm based on dual quaternions. We show that this approach solves the artifacts of linear blend skinning at minimal additional cost. Upgrading an existing animation system (e.g., in a videogame) from linear to dual quaternion skinning is very easy and has negligible impact on run-time performance.

Coding of vectorized cartoon video data

  • Autoři: Koloros, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Conference Proceedings - Spring Conference on Computer Graphics 2006. Bratislava: Comenius University, 2006, pp. 177-183. ISBN 80-223-2175-3. Available from: http://www.cgg.cvut.cz/~zara/papers/KolorosZara-SCCG06.pdf
  • Rok: 2006
  • DOI: 10.1145/2602161.2602182
  • Odkaz: https://doi.org/10.1145/2602161.2602182
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    We present an efficient video compression technique suitable for outline based cartoon animations. We adopt a new technique where the dynamic homogenous foreground layer is separated from the static textural background and each is coded using appropriate compression technique. The aim of this paper is to reduce temporal and spatial redundancy caused by similar region shape patterns in the foreground layer. Our shape matching methods are designed to be able to find identical and similar shapes even if they are transformed by translation, rotation or scaling. These methods will replace identical polygons by reference to the parent polygon and therefore save vertices. We have three steps applied on vectorized layer of video data. First the search for unchanged polygons within set of frames is being performed. Second similar polygons within one frame are being replaced by reference, and finally similar polygons within certain frame range are replaced by reference.

Efficient Collision Detection for Spherical Blend Skinning

  • Autoři: Kavan, L., O'Sullivan, C., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings. GRAPHITE 2006. New York: ACM SIGGRAPH, 2006. pp. 147-156. ISBN 1-59593-564-9.
  • Rok: 2006
  • DOI: 10.1145/1174429.1174452
  • Odkaz: https://doi.org/10.1145/1174429.1174452
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Recently, two algorithms improving the real-time simulation of articulated models in virtual environments have been published: 1) fast collision detection for linear blend skinning and 2) spherical blend skinning. Both linear and spherical blending solve the skinning problem of a skeletally controlled 3D model (e.g., an avatar), but only spherical blending avoids artifacts such as the candywrapper. This paper describes how to perform collision detection for models skinned with the more sophisticated spherical method. As a result, both high-quality skinning and fast and exact collision detection can be achieved - there is no longer any need for a trade-off. The generalization from linear to spherical lending involves the construction of rotation bounds, derived using a quaternion representation. The resulting algorithm is simple to implement and fast enough for real-time virtual reality applications.

Fast Approximation of Convex Hull

  • Autoři: Kavan, L., Kolingerová, I., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Advances in Computer Science and Technology - ACST 2006. Calgary: IASTED, 2006. p. 101-104. ISBN 0-88986-545-0.
  • Rok: 2006
  • Pracoviště: Katedra počítačů
  • Anotace:
    The construction of a planar convex hull is an essential operation in computational geometry. It has been proven that the time complexity of an exact solution is $\Omega(N log N)$. In this paper, we describe an algorithm with time complexity $O(N + k^2)$, where $k$ is parameter controlling the approximation quality. This is beneficial for applications processing a large number of points without necessity of an exact solution. A formula for upper bound of the approximation error is presented.

Fast Approximation to Spherical Harmonic Rotation

  • Autoři: Křivánek, J., Konttinen, J., Pattanaik, S., Bouatouch, K., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Conference Proceedings - Spring Conference on Computer Graphics 2006. Bratislava: Comenius University, 2006. p. 51-58. ISBN 80-223-2175-3.
  • Rok: 2006
  • DOI: 10.1145/2602161.2602167
  • Odkaz: https://doi.org/10.1145/2602161.2602167
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Rotation of functions represented by spherical harmonics is an important part of many real-time lighting and global illumination algorithms. For some of them a per-vertex or even per-pixel rotation is required, which implies the necessity of an efficient rotation procedure. The speed of any of the existing rotation procedures is, however, not able to meet the requirements of real-time lighting or fast global illumination. We present an efficient approximation of the spherical harmonic rotation applicable for small rotation angles. We replace the general spherical harmonic rotation matrix by its truncated Taylor expansion, which significantly decreases the computation involved in the rotation. Our approximation decreases the asymptotic complexity of the rotation---the higher the order of spherical harmonics, the higher the speed-up. We show applications of the proposed rotation approximation in global illumination and real-time shading. Although the rotation approximation is accurate on

Making Radiance and Irradiance Caching Practical: Adaptive Caching and Neighbor Clamping

  • Autoři: Křivánek, J., Bouatouch, K., Pattanaik, S., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Rendering Techniques 2006. Aire-la-Ville: Eurographics Association, 2006. p. 127-138. ISSN 1727-3463. ISBN 3-905673-35-5.
  • Rok: 2006
  • DOI: 10.2312/EGWR/EGSR06/127-138
  • Odkaz: https://doi.org/10.2312/EGWR/EGSR06/127-138
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Radiance and irradiance caching are efficient global illumination algorithms based on interpolating indirect illumination from a sparse set of cached values. In this paper we propose an adaptive algorithm for guiding spatial density of the cached values in radiance and irradiance caching. The density is adapted to the rate of change of indirect illumination in order to avoid visible interpolation artifacts and produce smooth interpolated illumination. In addition, we discuss some practical problems arising in the implementation of radiance and irradiance caching, and propose techniques for solving those problems. Namely, the neighbor clamping heuristic is proposed as a robust means for detecting small sources of indirect illumination and for dealing with problems caused by ray leaking through small gaps between adjacent polygons.

Virtual Reality Course - A Natural Enrichment of Computer Graphics Classes

  • DOI: 10.1111/j.1467-8659.2006.00921.x
  • Odkaz: https://doi.org/10.1111/j.1467-8659.2006.00921.x
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    This paper shows how the Virtual Reality (VR) course can naturally extend and practice a wide range of Computer Graphics (CG) principles and programming techniques. Thanks to real-time processing requirements, attention is paid to efficient modeling conventions, time-saving rendering approaches, and user interfaces allowing a smooth navigation in a virtual environment. All these issues play an important role especially when designing virtual worlds targeted to the web, i.e. utilizing VRML/X3D standards. The paper presents a structure and related information of the VR course that has been taught at various universities during the last 6 years. Our experience clearly demonstrates that students appreciate its contents even if they already completed courses on 3D graphics.

Virtual Reality in Neurorehabilitation: Mental Rotation

  • Autoři: Marušan, M., Kulišťák, P., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Third Central European Multimedia and Virtual Reality Conference. Veszprém: Pannonian University Press, 2006, pp. 77-83. ISBN 963-9495-89-1. Available from: http://www.cgg.cvut.cz/~zara/papers/MarusanKulistakZara-CEMVRC06.pdf
  • Rok: 2006
  • Pracoviště: Katedra počítačů
  • Anotace:
    This paper describes a Virtual Reality application for neurorehabilitation of patients following traumatic brain injuries (TBI). The application is based on mental rotation tasks frequently used to describe different human mental abilities and intial assessment of consequences of TBI.

Web-Based Historical City Walks: Advances and Bottlenecks

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: PRESENCE: Teleoperators and Virtual Environments. 2006, 15(3), 262-277. ISSN 1054-7460.
  • Rok: 2006
  • DOI: 10.1162/pres.15.3.262
  • Odkaz: https://doi.org/10.1162/pres.15.3.262
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    This paper deals with a set of useful methods for presenting large-scale models of real cities in a web environment. While acquisition issues are outlined only briefly, this study focuses on the optimal organization of city models and efficient rendering techniques. We also address data optimization for real-time delivery. The methods under discussion are illustrated by examples taken from several existing web presentations developed by our students, especially from the Virtual Old Prague project. Although the principles are general, specific attention is paid to the use of standards developed by the Web3D Consortium.

Colorization of Black-and-White Cartoons

  • DOI: 10.1016/j.imavis.2005.05.010
  • Odkaz: https://doi.org/10.1016/j.imavis.2005.05.010
  • Pracoviště: Katedra počítačů, Katedra počítačové grafiky a interakce
  • Anotace:
    We introduce a novel colorization framework for old black-and-white cartoons which has been originally produced by a cel or paper based technology. In this case the dynamic part of the scene is represented by a set of outlined homogeneous regions that superimpose static background. To reduce a large amount of manual intervention we combine unsupervised image segmentation, background reconstruction and structural prediction. Our system in addition allows the user to specify the brightness of applied colors unlike the most of previous approaches which operate only with hue and saturation. We also present a simple but effective color modulation, composition and dust spot removal techniques able produce color images in broadcast quality without additional user intervention.

eGaLab: a New Dimension for Artists

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc., Smetana, P.
  • Publikace: Computer Animation and Virtual Worlds. 2005, 2(16), 121-127. ISSN 1546-4261.
  • Rok: 2005
  • DOI: 10.1002/cav.63
  • Odkaz: https://doi.org/10.1002/cav.63
  • Pracoviště: Katedra počítačů
  • Anotace:
    eGaLab (electronic gallery and laboratory) for virtual art reflects today's status under which the artists create and present their artworks. It introduces an intuitive approach in the field of virtual environments and communities oriented to visual arts and artistic collaboration. eGaLab combines and transforms the advantages of collaborative virtual environments with the traditional aspects of artistic creation and presentation. In this paper we describe architecture of the eGaLab platform. We describe its networking part based on a concept of General Variables (GV) and discuss several implementation issues related to its specific character.

Fast Collision Detection for Skeletally Deformable Models

  • DOI: 10.1111/j.1467-8659.2005.00861.x
  • Odkaz: https://doi.org/10.1111/j.1467-8659.2005.00861.x
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    We present a new method of collision detection for models deformed by linear blend skinning. The linear blend skinning (also known as skeleton-subspace deformation, vertex-blending, or enveloping) is a popular method to animate believable organic models. We consider an exact collision detection based on a hierarchy of bounding spheres. The main problem with this approach is the update of bounding volumes - they must follow the current deformation of the model. We introduce a new fast method to refit the bounding spheres, which can be executed on spheres in any order. Thanks to this on-demand refitting operation we obtain a collision detection algorithm with speed comparable to the standard rigid body collision detection. The algorithm was tested on a variety of practical situations, including an animated crowd. According to these experiments, the proposed approach is considerably faster than the previous method.

Moderní počítačová grafika

  • Pracoviště: Katedra počítačů
  • Anotace:
    Neoficiální VŠ učebnice počítačové grafiky v Česku a na Slovensku. Obsahuje široký a ucelený průřez moderními metodami rovinné a prostorové počítačové grafiky.

Object-Oriented Approach to GIS Data Management

  • Autoři: Richta, T., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Sborník symposia GIS Ostrava 2005. Ostrava: VŠB-TUO, 2005. p. 1-7. ISSN 1213-239X.
  • Rok: 2005
  • Pracoviště: Katedra počítačů
  • Anotace:
    Paper discusses possibilities of combining the GIS and CAD data using object-oriented database management system.

Parallel Delaunay triangulation in E2 and E3 for computers with shared memory

  • Autoři: Kohout, J., Kolingerová, I., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Parallel Computing. 2005, 31(5), 491-522. ISSN 0167-8191.
  • Rok: 2005
  • DOI: 10.1016/j.parco.2005.02.010
  • Odkaz: https://doi.org/10.1016/j.parco.2005.02.010
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    This paper presents several parallel algorithms for the construction of the Delaunay triangulation in E2 and E3-one of the fundamental problems in computer graphics. The proposed algorithms are designed for parallel systems with shared memory and several processors. Such a hardware configuration (especially the case with two-processors) became widely spread in the last few years in the computer graphics area. Some of the proposed algorithms are easy to be implemented but not very efficient, while some of them prove opposite characteristics. Some of them are usable in E2 only, other work in E3 as well. The algorithms themselves were already published in computer graphics where the computer graphics criteria were highlighted. This paper concentrates on parallel and systematic point of view and gives detailed information about the parallelization of a computational geometry application to parallel and distributed computation oriented community.

Presenting Generalized Human Activities in Virtual Environment

  • Autoři: Štěpán, V., prof. Ing. Jiří Žára, CSc., Hlaváč, V.
  • Publikace: Proceedings of the 21st Spring Conference on Computer Graphics. New York: ACM, 2005, pp. 51-58. ISBN 1-59593-203-6. Available from: http://portal.acm.org/citation.cfm?id=1090132
  • Rok: 2005
  • DOI: 10.1145/1090122.1090132
  • Odkaz: https://doi.org/10.1145/1090122.1090132
  • Pracoviště: Katedra počítačů
  • Anotace:
    The EU cognitive vision project ActIPret (aimed at interpreting and understanding human manipulation activities) included a module for presentation of results in virtual reality (VR). This paper is mainly a detailed description of our solution - the ActIPret VR presentation module. Moreover we explain the specifics of cooperation between two areas with totally different view of the subject, such as cognitive vision an d virtual reality. Thus the paper can be viewed as an overview of our experience with this complicated sort of task.

Sketching Cartoons by Example

  • Pracoviště: Katedra počítačů, Katedra počítačové grafiky a interakce
  • Anotace:
    We introduce a novel example-based framework for reusing traditional cartoon drawings and animations. In contrast to previous approaches our aim is to design new characters and poses by combining fragments of the original artwork. Using standard image manipulation tool this task is tedious and time consuming. To reduce the amount of manual intervention we combine unsupervised image segmentation, fragment extraction and high-quality vectorization. The user can simply select an interesting part in the original image and then adjust it in a new composition using a few control scribbles. Thanks to ease of manipulation proposed sketch-based interface is suitable both for experienced artists and unskilled users (e.g. children) who wish to create new stories in the style of masters. Practical results confirm that using our framework high-quality cartoon drawings can be produced within much shorter time frames as compared with standard approaches.

Spherical Blend Skinning: A Real-time Deformation of Articulated Models

  • Autoři: Kavan, L., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings I3D 2005. New York: ACM SIGGRAPH, 2005. p. 9-16. ISBN 1-59593-013-2.
  • Rok: 2005
  • DOI: 10.1145/1053427.1053429
  • Odkaz: https://doi.org/10.1145/1053427.1053429
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    Skin deformation based on an underlying skeleton is a common method to animate believable organic models. The most widely used skeletal animation algorithm, linear blend skinning, is also known as skeleton subspace deformation, vertex blending, or enveloping. It runs in real-time even on a low-end hardware but it is also notorious for its failures, such as the collapsing-joints artifacts. We present a new algorithm which removes these shortcomings while maintaining almost the same time and memory complexity as the linear blend skinning. Unlike other approaches, our method works with exactly the same input data as the popular linear version. This minimizes the cost of upgrade from linear to spherical blend skinning in many existing applications: the data structures and models need no change at all. The paper discusses also theoretical properties of rotation interpolation, essential to spherical blend skinning.

Video Codec for Classical Cartoon Animations with Hardware Accelerated Playback

  • DOI: 10.1007/11595755_6
  • Odkaz: https://doi.org/10.1007/11595755_6
  • Pracoviště: Katedra počítačů, Katedra počítačové grafiky a interakce
  • Anotace:
    We introduce a novel approach to video compression which is suitable for traditional outline-based cartoon animations. In this case the dynamic foreground consists of several homogeneous regions and the background is static textural image. For this drawing style we show how to recover hybrid representation where the background is stored as a single bitmap and the foreground as a sequence of vector images. This allows us to preserve compelling visual quality as well as spatial scalability even for low encoding bit-rates. We also introduce an efficient approach to play back compressed animations in real-time on commodity graphics hardware. Practical results confirm that for the same storage requirements our framework provides better visual quality as compared to standard video compression techniques.

Virtual Reality Course - A Natural Enrichment of Computer Graphics Classes

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: Eurographics 05 - Education Papers. Aire-la-Ville: Eurographics Association, 2005. pp. 25-32. ISSN 1017-4656.
  • Rok: 2005
  • Pracoviště: Katedra počítačů
  • Anotace:
    This paper shows how the Virtual Reality (VR) course can naturally extend and practice a wide range of Computer Graphics (CG) principles and programming techniques. Thanks to real-time processing requirements, the attention is paid to efficient modeling conventions, time saving rendering approaches, and user interfaces allowing a smooth navigation in a virtual environment. All these issues play an important role especially when designing virtual worlds targeted to the web, i.e. utilizing VRML/X3D standards. The paper presents a structure and related information of the VR course that has been taught at various universities during the last six years. Our experience clearly demonstrates that students appreciate its contents even if they already completed courses on 3D graphics.

A Formal Approach to The Development of Web Based Multimedia Presentations

Adaptive Mesh Subdivision for Precomputed Radiance Transfer

  • Autoři: Křivánek, J., Pattanaik, S., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Spring Conference on Computer Graphics SCCG 2004 - Conference Proceedings. New York: ACM SIGGRAPH, 2004. pp. 106-111. ISBN 1-58113-914-4.
  • Rok: 2004

Authoring of Multimedia Presentations in Web Environment

  • Pracoviště: Katedra počítačů
  • Anotace:
    The paper describes the development of a framework for uniform handling of multimedia documents.

Color for Black-and-White Cartoons

  • Pracoviště: Katedra počítačů
  • Anotace:
    In this paper we discuss a challenging problem of applying novel color information into the old black-and-white cartoons. Thanks to a possibility, which allows us to convert the original analogue material to the sequence of digital images, we are able to solve this task using methods of digital image-processing.

Cooperative Design for Artistic Performances

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc., Získal, B., Smetana, P.
  • Publikace: Cooperative Design, Visualization, and Engineering. Berlin: Springer, 2004. pp. 180-185. ISSN 0302-9743. ISBN 3-540-23149-8.
  • Rok: 2004
  • DOI: 10.1007/978-3-540-30103-5_21
  • Odkaz: https://doi.org/10.1007/978-3-540-30103-5_21
  • Pracoviště: Katedra počítačů
  • Anotace:
    ALTERNE (Alternative Realities in Networked Environments) platform aims at providing a high level of integration between various techniques supporting mixed reality, graphics, interaction and behavioral models. This paper focuses on two collaborative aspects the platform provides. First, it contains a virtual object repository, which allows artists to share their ideas and support collaboration on projects based on ALTERNE platform. Second, it enables direct and remote access for public visitors to the artistic installations so that all concurrent visitors can cooperate on the exploration of the installation.

Interest Management for Collaborative Environments Through Dividing Their Shared State

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Cooperative Design, Visualization, and Engineering. Berlin: Springer, 2004. pp. 156-163. ISSN 0302-9743. ISBN 3-540-23149-8.
  • Rok: 2004
  • DOI: 10.1007/978-3-540-30103-5_18
  • Odkaz: https://doi.org/10.1007/978-3-540-30103-5_18
  • Pracoviště: Katedra počítačů
  • Anotace:
    In this paper we present an interest management technique that organizes the shared state into domains and sub-domains and enables clients to express their interest in particular sub-domains only. This approach specifies an interest management in a general way and it can be used for a wide range of CVE applications. Key ideas are being implemented as part of General Variables (GV) library and verified in our testbed CVE system for social interaction called e-Agora.

Methods for Modeling and Rendering Atmospheric Phenomena

Practically Oriented Parallel Delaunay Triangulation in E2 for Computers with Shared Memory

  • Autoři: Kohout, J., Kolingerová, I., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Computers & Graphics. 2004, 28(5), 703-718. ISSN 0097-8493.
  • Rok: 2004
  • DOI: 10.1016/j.cag.2004.06.009
  • Odkaz: https://doi.org/10.1016/j.cag.2004.06.009
  • Pracoviště: Katedra počítačů
  • Anotace:
    This paper describes two simple and efficient parallel algorithms for the construction of the Delaunay triangulation (DT(S)) in E2 by randomized incremental insertion. The construction of the DT(S) is one of the fundamental problems in computer graphics. The proposed algorithms are designed for parallel systems several processors and with shared memory. Such a hardware configuration (especially the case with two-processors) became widely available in the last few years thanks to low prices at present, but there is still a lack of parallel algorithms that are simple to implement and efficient enough to be an attractive alternative to existing serial algorithms. We have implemented both new algorithms in C++ and tested them on workstations with up to four processors. Thanks to memory caching we noticed several times even super-linear speed-up compared with the reference sequential algorithm.

Radiance Caching for Fast Global Illumination with Arbitrary BRDFs

  • Autoři: Křivánek, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of Workshop 2004. Praha: České vysoké učení technické v Praze, 2004, pp. 224-225. ISBN 80-01-02945-X. Available from: http://www.cgg.cvut.cz/~xkrivanj/papers/workshop2004/krivanek-workshop2004-abstract.pdf
  • Rok: 2004
  • Pracoviště: Katedra počítačů
  • Anotace:
    We present a ray tracing based method for accelerated global illumination computation in scenes with low-frequency glossy BRDFs. The method is based on sparse sampling, caching, and interpolating radiance on glossy surfaces. In particular we extend the irradiance caching scheme of Ward et al. [1988] to cache and interpolate directional incoming radiance instead of irradiance. The incoming radiance at a point is represented by hemispherical harmonics. The surfaces suitable for interpolation are selected automatically according to the glossiness of their BRDF. We also propose a novel method for computing translational radiance gradient at a point.

Unsupervised Colorization of Black-and-White Cartoons

  • DOI: 10.1145/987657.987677
  • Odkaz: https://doi.org/10.1145/987657.987677
  • Pracoviště: Katedra počítačů
  • Anotace:
    We present a novel color-by-example technique which combines image segmentation, patch-based sampling and probabilistic reasoning. This method is able to automate colorization when new color information is applied on the already designed black-and white cartoon. Our technique is especially suitable for cartoons digitized from classical celluloid films, which were originally produced by a paper or cel based method. We assume that objects in the foreground layer consist of several well visible outlines which will emphasize the shape of homogeneous regions.

Virtual Campeche: A Web Based Virtual Three-Dimensional Tour

  • Autoři: prof. Ing. Jiří Žára, CSc., Beneš, B., Rodarte, R.R.
  • Publikace: Proceedings of the Fifth Mexican International Conference in Computer Science (ENC '04). New York: IEEE Computer Society Press, 2004. pp. 133-140. ISBN 0-7695-2160-6.
  • Rok: 2004
  • DOI: 10.1109/ENC.2004.1342598
  • Odkaz: https://doi.org/10.1109/ENC.2004.1342598
  • Pracoviště: Katedra počítačů
  • Anotace:
    We present a web-based application that allows a user to walk through, see, and interact with a fully three-dimensional model of an old Mexican city. Campeche is of enormous historical value and has been placed by UNESCO on their list of the World Cultural Heritage sites. A virtual visit can benefit both tourists and scientists. We show how the model was created and how certain technical issues were addressed.

Virtual Heart of Central Europe

  • Autoři: Ferko, A., Martinka, J., Sorman, M., Karner, K., prof. Ing. Jiří Žára, CSc., Krivograd, S.
  • Publikace: Proceedings of 9th symposion on INFO- & COMMUNICATION TECHNOLOGY in URBAN- AND SPATIAL PLANNING and IMPACTS OF ICT ON PHYSICAL SPACE. Wien: Technische Universität, 2004. p. 193-200.
  • Rok: 2004
  • Pracoviště: Katedra počítačů
  • Anotace:
    Presentation of the cultural heritage oriented EC project for documentation, digital preservation, and on-line dissemination of selected towers, wells, and rarities in Prague, Graz, Maribor, and Bratislava. An overview of the methodology, technology, and digital content including digital storytelling.

Virtual Reality and Cultural Heritage on the Web

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: 7th International Conference Computer Graphics and Artificial Inteligence - Proceedings of the Conference. Limoges: Universite de Limoges, 2004. p. 101-112. ISBN 2-914256-06-X.
  • Rok: 2004
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    The paper presents various issues dealing with presentation of cultural heritage objects in a virtual space. The attention is paid to the visualization approaches for wide audience, i.e. techniques targeted to the web. Due to the diversity of network connections and performance of computers used by ordinary users, the efficient representation of virtual objects plays an important role. Web-based presentation of three dimensional scenes requires specific user interfaces. Those issues are discussed and accompanied by examples and practical experience from the design and implementation of the EU project Virtual Heart of Central Europe.

Visualization and Virtual Cities

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: Prague CODATA Information Visualization Workshop. Praha: České vysoké učení technické v Praze, 2004, pp. 54-59.
  • Rok: 2004

VRI Exhibition

Cultural Heritage Presentation in Virtual Environment: Czech Experience

  • DOI: 10.1109/DEXA.2003.1232004
  • Odkaz: https://doi.org/10.1109/DEXA.2003.1232004
  • Pracoviště: Katedra počítačů
  • Anotace:
    This paper introduces three different approaches to cultural heritage modeling and presentation in the Czech Republic. The first example, Celtic oppidum Závist, represents a simple but efficient utilization of the virtual reality for the archaeology. Next project, the Virtual Old Prague, is a complex web-based application allowing dynamic walks through virtual cities. Such models can be theoretically of any size. Finally, the on-going EU project, Virtual Heart of Central Europe, is an example of several cultural heritage sites thematically interconnected

Describing Human Activities for VR Presentation

  • Autoři: Štěpán, V., prof. Ing. Jiří Žára, CSc., Hlaváč, V.
  • Publikace: Visualization, Imaging, and Image Processing. Anaheim: Acta Press, 2003, pp. 37-42. ISSN 1482-7921. ISBN 0-88986-382-2. Available from: http://www.cgg.cvut.cz/~zara/papers/StepanZaraHlavac-VIIP03.pdf
  • Rok: 2003

eGaLab - a New Dimension for Artists

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc., Smetana, P.
  • Publikace: Proceedings 2003 International Conference on Cyberworlds. Los Alamitos: IEEE Computer Society Press, 2003. p. 466-471. ISBN 0-7695-1922-9.
  • Rok: 2003
  • DOI: 10.1109/CYBER.2003.1253491
  • Odkaz: https://doi.org/10.1109/CYBER.2003.1253491
  • Pracoviště: Katedra počítačů
  • Anotace:
    Introduction and description of the architecture of the eGaLab platform, which is a framework for cooperative creation of artworks in a virtual environment. The networking part is based on our concept of General Variables.

Fast Depth of Field Rendering with Surface Splatting

  • Autoři: Křivánek, J., prof. Ing. Jiří Žára, CSc., Bouatouch, K.
  • Publikace: Proceedings of Computer Graphics International 2003. Los Alamitos: IEEE Computer Society Press, 2003. p. 196-201. ISSN 1530-1052. ISBN 0-7695-1946-6.
  • Rok: 2003
  • DOI: 10.1109/CGI.2003.1214466
  • Odkaz: https://doi.org/10.1109/CGI.2003.1214466
  • Pracoviště: Katedra počítačů
  • Anotace:
    We present a new fast algorithm for rendering the depth-of-field effect for point-based surfaces. The proposed algorithm is an extension of the Elliptical Weighted Average (EWA) surface splatting.

Preparation and Presentation of Cultural Content in Virtual Environment

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of Electronic Imaging 2003 - Internet Imaging IV. Bellingham: SPIE, 2003, pp. 72-79. ISSN 0277-786X. ISBN 0-8194-4818-4. Available from: http://www.cgg.cvut.cz/~zara/papers/Zara-EI2003.pdf
  • Rok: 2003
  • DOI: 10.1117/12.473367
  • Odkaz: https://doi.org/10.1117/12.473367
  • Pracoviště: Katedra počítačů
  • Anotace:
    The paper presents a web-based application for preparation and presentation of various two- and three-dimensional cultural showpieces in a virtual environment. Specific task modules built on a common database provide tools for designing spatial models of a real or a fully virtual gallery, exhibit management, arrangement of exhibits within the virtual space, and final web presentation using standard VRML browser and Java applet. The whole application serves for different kinds of users - gallery owners, artists, and visitors. A use of virtual reality paradigms for image presentation purposes is discussed here, too.

Preparation and presentation of cultural content in virtual environment

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of Electronic Imaging 2003 - Internet Imaging IV. Bellingham: SPIE, 2003, pp. 72-79.
  • Rok: 2003
  • Pracoviště: Katedra počítačů
  • Anotace:
    Preparation and presentation of cultural content in virtual environment

Projekt virtuální staré Prahy

  • Pracoviště: Katedra počítačů
  • Anotace:
    Přehledná informace o projektu Virtuální Stará Praha pro širokou veřejnost

Real Time Skin Deformation with Bones Blending

  • Autoři: Kavan, L., prof. Ing. Jiří Žára, CSc.,
  • Publikace: WSCG'2003 Short papers. Pilsen: University of West Bohemia, 2003. p. 69-74. ISBN 80-903100-1-X.
  • Rok: 2003
  • Pracoviště: Katedra počítačů
  • Anotace:
    Skeletal animation with vertex blending is a popular method to model believable 3D characters. Its main advantage is its speed that allows real-time deformation even on low-level hardware. However it has some drawbacks as well: for some movements it produces non-natural postures like twisting elbows. We present a new method called bones blending that can be used as an alternative to vertex blending. Bones blending has a power to overcome the artifacts of vertex blending.

Segmentation of Black and White Cartoons

Simulation of Natural Environment in Virtual Reality

  • Autoři: Chludil, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of Workshop 2003 (online). Praha: České vysoké učení technické v Praze, 2003, pp. 200-201. ISBN 80-01-02708-2. Available from: http://web.cvut.cz/ctu/research/workshop/ws2003.pdf
  • Rok: 2003

Classification of Systems for Simulation and Visualization of Physical Phenomena

  • Autoři: Chludil, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of Workshop 2002. Praha: České vysoké učení technické v Praze, 2002, pp. 284-285. ISBN 80-01-02511-X.
  • Rok: 2002

Classification of Systems for Simulation and Visualization of Physical Phenomena

  • Autoři: Chludil, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Journal of WSCG'2002. Plzeň: Západočeská universita, 2002, pp. 17-20. ISSN 1213-6980.
  • Rok: 2002

Classification of Systems for Simulation and Visualization of Physical Phenomena

  • Autoři: Chludil, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: WSCG '2002 Posters. Plzeň: Západočeská universita, 2002, pp. 17-20. ISBN 80-903100-0-1.
  • Rok: 2002

Concise Tour to the Virtual Old Prague

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: EUROGRAPHICS 2002, Short Presentations. Saarbrücken: Eurographics Association, 2002, pp. 191-198. ISSN 1017-4656. Available from: http://www.cgg.cvut.cz/~zara/papers/Zara-EG2002.pdf
  • Rok: 2002

From Textual Chats to Interest Groups in 3D Virtual Space

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: EUROGRAPHICS 2002, Short Presentations. Saarbrücken: Eurographics Association, 2002, pp. 199-205. ISSN 1017-4656. Available from: http://www.cgg.cvut.cz/~zara/papers/MasaZara-EG02.pdf
  • Rok: 2002

Generalized Interest Management in Virtual Environments

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: CVE 2002 - Proceedings of the 4th International Conference on Collaborative Virtual Environments. New York: ACM Press, 2002, pp. 149-150. ISBN 1-58113-489-4. Available from: http://www.cgg.cvut.cz/~zara/papers/MasaZara-CVE02.pdf
  • Rok: 2002

Interactive Virtual Gallery

  • Autoři: Ulrich, T., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Spring Conference on Computer Graphics - SCCG 2002. New York: ACM, 2002, pp. 43-47. ISBN 1-58113-608-0. Available from: http://www.cgg.cvut.cz/~zara/papers/UllrichZara-SCCG02.pdf
  • Rok: 2002

Nautilus - The Environment for Training and Testing

  • Autoři: Chludil, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of the Sixth IEEE International Workshop on Distributed Simulation and Real-Time Applications. Los Alamitos: IEEE Computer Society Press, 2002. pp. 134-139. ISSN 1530-1990. ISBN 0-7695-1853-2.
  • Rok: 2002
  • DOI: 10.1109/DISRTA.2002.1166899
  • Odkaz: https://doi.org/10.1109/DISRTA.2002.1166899
  • Pracoviště: Katedra počítačů
  • Anotace:
    The paper describes an experimental web-based environment for teaching and testing. The application named Nautilus has been developed using Virtual Reality Modeling Language (VRML) and Java language with two special libraries: DILEWA and Vrmlworld. Although the resulting system is intended for low-level virtual reality systems without any specialized hardware support it is powerful enough to accurately simulate various situations and scenarios. Currently implemented multi-user environment for training and testing of yacht captains serves as an experimental workbench for creation of general applications where a developer combines a simulated environment from simpler simulation elements. Design and implementation of the system are presented together with several practical observations concerning efficiency of the real-time rendering and the level of implementation difficulty.

On the Complexity of Web-based Presentations of Large Urban Scenes

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: East-West-Vision 2002. Wien: Österreichische Computer Gesellschaft, 2002, pp. 99-108. ISBN 3-85403-163-7. Available from: http://www.cgg.cvut.cz/~zara/papers/Zara-EWV2002.pdf
  • Rok: 2002
  • Pracoviště: Katedra počítačů
  • Anotace:
    The overview of methods for 3D modelling and visualization of large city areas on the web.

Teaching Tennis In Virtual Environment

  • Autoři: Štěpán, V., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Spring Conference on Computer Graphics - SCCG 2002. New York: ACM, 2002. pp. 49-54. ISBN 1-58113-608-0.
  • Rok: 2002
  • DOI: 10.1145/584458.584467
  • Odkaz: https://doi.org/10.1145/584458.584467
  • Pracoviště: Katedra počítačů
  • Anotace:
    This paper deals with the problems of human animation and motion analysis, particularly in the area of methodological applications in sports training. We describe a particular program tool that has been implemented as a Java applet connected to the VRML browser through the Java EAI interface. Various aspects of this solution are discussed, as well as motion analysis and its significance for sport oriented applications.

A Scaleable Approach to Visualization of Large Virtual Cities

  • Autoři: prof. Ing. Jiří Žára, CSc., Chromý, P., Čížek, J., Ghais, K., Holub, M., Mikeš, S., Rajnoch, J.
  • Publikace: Proceedings Fifth International Conference on Information Visualisation. Los Alamitos: IEEE Computer Society Press, 2001. pp. 639-644. ISBN 0-7695-1195-3.
  • Rok: 2001

DILEWA: The DIstributed Learning Environment Without Avatars and the Concept of General Variables

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Poster 2001. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2001, pp. IC26.
  • Rok: 2001

Editing VRML Worlds in Multi-User Environment

  • Autoři: Dorňák, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of the 5th Central European Seminar on Computer Graphics. Vienna: Institute of Computer Graphics and Algorithms, 2001, pp. 203-212.
  • Rok: 2001

Graphics Performance Benchmarking Based on VRML Browsers

  • Autoři: prof. Ing. Jiří Žára, CSc., Křivánek, J.
  • Publikace: VRIC 2001 Proceedings. Laval: ISTIA Innovation, 2001, pp. 111-120. ISBN 2-9515730-0-6. Available from: http://www.cgg.cvut.cz/~zara/papers/ZaraKrivanek-Laval01.pdf
  • Rok: 2001
  • Pracoviště: Katedra počítačů
  • Anotace:
    The set of benchmarks for graphic performance has been designed and implemented taking practical users' needs into consideration. As 3D technology begins to be a very common part of Internet presentations and applications, high interest of appropriate hardware and software combination for virtual reality can be expected. This paper introduces benchmarks based on usage of different VRML browsers. In contrast with testing of basic but low-level tasks (e.g. number of triangles per second), our approach is oriented to a real throughput of practically used computers. Measurements on various computer configurations are presented and discussed.

Jazyk VRML bude bohatší

Nejmladší z rodu "empegů"

Stará a nová architektura ve virtuálním kabátě

The General Variables Concept: A Simple Step from Single- to Multi-user Environment

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings Fifth International Conference on Information Visualisation. Los Alamitos: IEEE Computer Society Press, 2001. pp. 584-588. ISBN 0-7695-1195-3.
  • Rok: 2001

Virtual House of European Culture: e-AGORA

  • Autoři: Adamec, J., Čížek, J., Máša, M., Silondi, P., Smetana, P., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Virtual Storytelling. Berlin: Springer, 2001. pp. 208-211. ISSN 0302-9743. ISBN 3-540-42611-6.
  • Rok: 2001

Yacht Captain Training System in Virtual Environment

  • Autoři: Chludil, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Poster 2001. Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 2001, pp. IC15.
  • Rok: 2001

Yacht Captain Training System in VRML

  • Autoři: Chludil, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: NATO PfP/PWP Workshop - CATE 2001. Brno: Vojenská akademie, 2001, pp. 1-8.
  • Rok: 2001

Změřte si svoji grafiku

DILEWA: The DIstributed Learning Environment Without Avatars

  • Autoři: Máša, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings IEEE International Conference on Information Visualisation. Los Alamitos: IEEE Computer Society Press, 2000. p. 563-567. ISBN 0-7695-0743-3.
  • Rok: 2000

On Design of 3D and Multimedia Extension of Information System Using VRML

  • Autoři: prof. Ing. Jiří Žára, CSc., Černohorský, D.
  • Publikace: Proceedings 3rd Workshop on Virtual Reality. Rio de Janeiro: Brazilian Computer Society - SBC, 2000, pp. 99-106. Available from: http://www.cgg.cvut.cz/~zara/papers/Zara-WRV2000.pdf
  • Rok: 2000

VIS-RT: A Visualization System for RT Spatial Data Structures

CAD a VR, jak se to rýmuje?

Distant Learning and Cooperation in VRML

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: Role of Universities in the Future Information Society. Flagstaff: Northern Arizona University, 1999, pp. 1-6. Available from: http://www.cgg.cvut.cz/~zara/papers/Zara-RUFIS99.pdf
  • Rok: 1999

Remote VRML Browser Control Using EAI

  • Autoři: Kubec, M., prof. Ing. Jiří Žára, CSc.,
  • Publikace: 3rd Central European Seminar on Computer Graphics. Wien: Technische Universität, 1999, pp. 69-78.
  • Rok: 1999

S CAD na Internet

Trikové prvky ve VRML

VRML 97 - Laskavý průvodce virtuálními světy

VRML 97 - Ono se to hýbe!

VRML 97 - Postavím si domeček, v tom domečku

Ztraceni ve virtuálních světech?

Avataři všech zemí, spojte se!

Grafikou hýbe zábava a film

Moderní počítačová grafika

Ray Tracing with Rope Trees

SIGGRAPH věští budoucnost

Týden pokušení v ráji grafiků

Using VRML for Creating Interactive Demonstrations of Physical Models

  • Autoři: prof. Ing. Jiří Žára, CSc., Cibulka, K.
  • Publikace: Proceedings of the 2nd CESCG '98. Wien: Technische Universität, 1998, pp. 25-35.
  • Rok: 1998

View Dependent Data Structures for Ray Tracing

An Introduction to Virtual Reality Modeling Language

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: SOFSEM'97: Theory and Practice of Informatics. Berlin: Springer, 1997. pp. 331-348. ISBN 3-540-63774-5.
  • Rok: 1997

Evaluation of BSP Properties for Ray-tracing

Fast Robust BSP Tree Traversal Algorithm for Ray Tracing

  • DOI: 10.1080/10867651.1997.10487481
  • Odkaz: https://doi.org/10.1080/10867651.1997.10487481
  • Pracoviště: Katedra počítačů, Katedra počítačové grafiky a interakce
  • Anotace:
    An orthogonal BSP (binary space partitioning) tree is a commonly used spatial subdivision data structure for ray tracing acceleration. While the construction of a BSP tree takes a relatively short time, the efficiency of a traversal algorithm significantly influences the overall rendering time. We propose a new fast traversal algorithm based on statistical evaluation of all possible cases occurring during traversing a BSP tree. More frequent cases are handled simply, while less frequent ones are more computationally expensive. The proposed traversal algorithm handles all singularities correctly. The algorithm saves from 30% up to 50% of traversal time comparing with the commonly-known Sung and Arvo algorithms.

Jazyk VRML pro modelování virtuální reality

Multimedia Information System in 3D Space (MISS)

  • Autoři: prof. Ing. Jiří Žára, CSc., Zrzavý, J.
  • Publikace: RUFIS '97. Proceedings for International Part of the Conference. Praha: České vysoké učení technické v Praze, 1997, pp. 213-218. ISBN 80-01-01710-9. Available from: http://www.cgg.cvut.cz/~zara/papers/Zara-RUFIS97.pdf
  • Rok: 1997

Three Medical Image Segmentation Algorithms

VRML - jazyk pro virtuální realitu

Vystačíme s osmi bity?

Channel - a Generalized Pipe

  • Autoři: Hejda, P., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of the Fourth International Conference in Central Europe on Computer Graphics and Visualisation. Plzeň: Západočeská universita, 1996, pp. 244-245. ISBN 80-7082-239-2.
  • Rok: 1996

Language Support for Distributed Virtual Reality

  • Autoři: Beneš, B., Holeček, A., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of the Fourth International Conference in Central Europe on Computer Graphics and Visualisation. Plzeň: Západočeská universita, 1996, pp. 233-243. ISBN 80-7082-239-2.
  • Rok: 1996

On Segmentation for Medical Data Visualization

Open GL - Nové paradigma v počítačové grafice?

Systémy pro vizualizaci dat

The Labyrinth Project

  • Autoři: Hejda, P., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Workshop 96. Praha: České vysoké učení technické v Praze, 1996, pp. 279-280.
  • Rok: 1996

Three-Dimensional Information System on the World Wide Web

Towards Knowledge Based Segmentation of Brain Structures

Za tajemstvím OpenGL

Color Information Processing

Interaktivní vizualizace dat - Explorer

Laboratoř počítačové grafiky na FEL ČVUT

Load Balancing for Parallel Raytracer on Virtual Walls

  • Autoři: Menzel, K., Buriánek, J., Holeček, A., Přikryl, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of the Third International Conference in Central Europe on Computer Graphics and Visualisation 95. Plzeň: Západočeská universita, 1995. pp. 439-447. ISBN 80-7082-187-6.
  • Rok: 1995

Loadbalancing for Distributed Raytracer

  • Autoři: Holeček, A., Přikryl, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Workshop 95. Praha: České vysoké učení technické v Praze, 1995, pp. 167-168.
  • Rok: 1995

Segmentace a vizualizace dat z MR tomografu

  • Autoři: Ing. Petr Felkel, Ph.D., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Sborník příspěvků na pracovním setkání "Výuka a výzkum v oblasti biomedicínského inženýrství a biotechnologií na FEL ČVUT v Praze". Praha: České vysoké učení technické v Praze, Fakulta elektrotechnická, 1995, pp. 62.
  • Rok: 1995

Speeding Up Ray Tracing - SW and HW Approaches

  • Autoři: prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of 11th Spring Conference on Computer Graphics - SSCG 95. Bratislava: Dom techniky, 1995, pp. 1-16. ISBN 80-233-0344-9.
  • Rok: 1995

The Simulation of the Real Camera for the Rendering

  • Autoři: Havran, V., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Workshop 95. Praha: České vysoké učení technické v Praze, 1995, pp. 183-184.
  • Rok: 1995

VirtMed - a Project of 3D Medical Data Processing and Visualization

Distributed Ray Tracing under PVM

  • Autoři: prof. Ing. Jiří Žára, CSc., Holeček, A., Přikryl, J.
  • Publikace: CTU Seminar 94. Praha: České vysoké učení technické v Praze, 1994, pp. 93-94.
  • Rok: 1994

Distributed Rendering Techniques Using Virtual Walls

  • Autoři: Menzel, K., Schmidt, O., Stangenberg, F., Hornung, C., Lange, B., Holeček, A., Přikryl, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of First European PVM Users Group Meeting. Roma: University of Roma, 1994, pp. 1-10.
  • Rok: 1994

Parallelisation of the Ray-tracing Algorithm

  • Autoři: Holeček, A., Přikryl, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of Winter School of Computer Graphics and CAD Systems 94. Plzeň: Západočeská universita, 1994, pp. 113-117.
  • Rok: 1994

When the Parallel Ray-tracer Starts to Be Efficient?

  • Autoři: Holeček, A., Přikryl, J., prof. Ing. Jiří Žára, CSc.,
  • Publikace: Proceedings of Spring School on Computer Graphics. Bratislava: Univerzita Komenského, 1994, pp. 108-116. ISBN 80-223-0801-3.
  • Rok: 1994

Design of Parametric Construction Parts

Solution of Form Factors in Radiosity Method

The Roof Construction Problem Algorithm

Počítačová grafika - Principy a algoritmy

Za stránku zodpovídá: Ing. Mgr. Radovan Suk