Short Presentations
Permanent URI for this collection
Browse
Browsing Short Presentations by Title
Now showing 1 - 20 of 50
Results Per Page
Sort Options
Item Adaptive Compression of Human Animation Data(Eurographics Association, 2002) Ahmed, Amr Adel Hassan; Hilton, Adrian; Mokhtarian, FarzinIn this paper we introduce an adaptive motion compression technique using the discrete wavelet transform. Based on the analysis of human animation data, and its frequency contents, the wavelet analysis is utilised to achieve motion compression. It has been found that even with high compression ratios (up to 86%), the compressed animation is visually very close to the original animation. This property is potentially useful for many areas of animation such as motion interpolation/blending and networked virtual environments. One of our motivations is that motion blending/interpolation between motion capture samples is one of the successful techniques for synthesis of novel realistic human animation. One of the major concerns of that method is the increase of the database size with the large number of samples required to synthesise a wide range of movements. Previous research has addressed this issue by trying to reduce the number of samples required for interpolation. The approach that we introduce in this paper is to reduce the individual sample’s size using compression. Integration of both these approaches promises to allow a realistic animation with reduced database size. In networked virtual environments and on-line games, compressing the animation data can reduce the transmission load and help in achieving real-time performance and realism with reduced cost.Item Adaptive Tessellation for Trimmed NURBS Surface(Eurographics Association, 2002) YingLiang, Ma; Hewitt, TerryWe present an adaptive method for tessellating the trimmed NURBS surface in the parametric domain. Given a model space tolerance ε, the algorithm first splits the NURBS surface in both the U and V directions to fit within the bounding box of the outer trimming loop. Then we subdivide the surface into Bézier patches recursively until the control net of the Bézier patch is flat enough and within the tolerance ε. By building up the quadtrees of inner trimming loops, we use the scanline algorithm to remove the patches inside the inner trimming loops. Finally, we close the inner trimming loops with a set of triangles. The resulting tessellation contains both quadrilaterals and triangles.Item Automated Enhancement of 3D Models(Eurographics Association, 2002) Torres-Mendez, L.A.; Dudek, G.The acquisition of a 3D model of a real environment can be accomplished using range sensors. In practice, suitable sensors to densely cover a large environment are often impractical. This paper presents ongoing work on the synthesis of 3D environment models from as little as one intensity image and sparse range data. Our method is based on interpolating the available range data using statistical inferences learned from the available intensity image and from those (sparse) regions where both range and intensity information is available. Since we compute the relationship between extisting range data and the images we start with, we do not need to make any strong assumptions about the kind of surfaces in the world (for example we do not need to assume the world exhibits only diffuse reflectance). Experimental results show the feasibility of our method.Item Automatic Data Acquisition and Visualization for Usability Evaluation of Virtual Reality Systems(Eurographics Association, 2002) Holm, Roland; Priglinger, Markus; Stauder, Erwin; Volkert, J.; Wagner, R.Evaluating the usability of a Virtual Reality system is a common practice nowadays. However, gathering and analyzing the necessary data are time-consuming tasks and sometimes involve inconvenient changes to the system. The VR-based safety training system SAVE suffered from this problem. Therefore, independent modules have been developed to acquire and visualize usability relevant data to allow extensive evaluation sessions to be performed efficiently. Interaction and simulation data is acquired automatically and joined with external physiological data to be visualized inside a complete 3D representation of the training scenario. Visualizations can be performed in real-time while acquiring the data during a session, or from recorded data after the session has been completed. Because the visualization is coupled with a VR authoring tool, it is also possible to analyze the usability of a VR scenario and perform changes instantly.Item Concise Tour to the Virtual Old Prague(Eurographics Association, 2002) Zara, JiriThis paper describes a structure and a user interface of the Internet based 3D presentation of existing historical part of city Prague. The application offers a smooth tour to selected regions of the real city, utilizing number of standard and modern technologies including VRML, Java, and PHP. The architecture of the whole virtual model is presented together with several advanced and specific features like dynamic loading und unloading objects or newly proposed LOD for urban scenes. This running web application seems to be currently unique in terms of complexity, functionality, and scaleability for further growth. The paper introduces methodology suitable for immediate creation of arbitrary virtual city according to a real one.Item A Convolution-Based Algorithm for Animated Water Waves(Eurographics Association, 2002) Loviscach, JörnA non-linear partial differential equation solver is too sophisticated for computer graphics applications if they are only used to render effects like circular waves and ship wakes. We present an approach which simulates waves through a convolution algorithm. It handles both gravity waves and capillary waves; the latter are often neglected even though they dominate small-scale behavior. The algorithm can be integrated into a complete solution architecture: First, standard commercial 3-D software is used to prepare an animated scene with objects traveling on a water surface. Based on the movements of these objects, waves are calculated and added as bump and displacement maps to the 3-D model.Item Dependent Tests Driven Filtering in Monte-Carlo Global Illumination(Eurographics Association, 2002) Csonka, Ferenc; Szirmay-Kalos, Laszlo; Kelemen, Csaba; Antal, GyörgyThis paper presents a multi-phase algorithm to solve the global illumination problem. In the first phase dependent tests are applied, i.e. the random walks of different pixels are built from the same random numbers. The result of the first phase is used to identify homogeneous pixel groups in the image. The criterion of the formation of such groups is that averaging the color inside these groups should result in less error than handling the pixels independently. The second phase of the algorithm is a conventional random walk method that uses independent random samples in different pixels. The final result is calculated as the average of the results of the dependent tests and the lowpass filtered version of the independent tests. This low-pass filter averages the pixel values inside the homogenous groups. The algorithm takes advantage of the fact that the image can contain larger homogeneous regions that can be calculated from much less number of samples. Thus we can focus on those pixels where significant changes happen.Item Digital Watermarking for Volumetric Datasets(Eurographics Association, 2002) Dimitrov, Leonid I.; Sramek, MilosAn idea for digitaly watermarking volumetric datasets (VDS) and preliminary results from a test implementation are presented. It consists of a combination of filtering and rendering operations on volumetric data allowing for identification of the voxels suitable for hiding the watermark and spreading the information in the gradients of the selected voxels. Thus, a secure and robust method for watermarking VDS could be developed which takes into account the specific properties of volumetric data and advantageously utilizes them.Item Distance fields applied to character animation(Eurographics Association, 2002) Rudomin, Isaac; Castillo, J.A general hybrid geometric-physical method that is useful for animating characters with skin, clothing and a MPEG-4 compatible face is presented. This method uses an approximation to the underlying musculo-skeletal structure of the body and face to generate a distance field, used for collision detection purposes, and skin/clothing consisting of a particle-spring mesh. The results obtained deliver animation with plausible dynamics for fairly detailed models at around 60fps on a PIII computer with Nvidia Gforce2 graphics. The main contribution is to show that similar algorithms can be used for skin, clothing and facial animation, at interactive rates.Item Dynamic Motion Models(Eurographics Association, 2002) Grünvogel, Stefan Michael; Lange, Thorsten; Piesk, JensReal-time animation of virtual characters is a demanding task. We propose dynamic motion models which can create the motion of a virtual character in different styles and have the ability to change the animation while it is played. The motions are created by blending and changing given base motions which contain animation data and additional information. The blending and manipulation operations on the animation data build up a motion tree which can be altered dynamically in real-time. This allows to change the animation of a motion model while its animation is played. Motion trees of different motion models are blended together to build a motion tree which represents the complete animation of the character. This tree is constructed and dynamically changed according to user commands.Item Dynamics-Based Motion Synthesis by Simple Learning Control(Eurographics Association, 2002) Kiriazov, PetkoPoint-to-point motion of a humanoid agent (or any mobile creature) is considered as a composition of basic movements related to the degrees of freedom. With time/energy performance criteria, such movements can be synthesized by using simple control functions. Natural looking animation can be achieved employing even very simplified dynamics models. Their parameters can be estimated or identified using motion capture data. In case no appropriate dynamic model is available, we propose an efficient procedure of direct motion editing. The captured motion can be re-used in order to animate the original or other characters in a variety of similar motion tasks. The proposed approach for motion synthesis is applied in the case of a six-link biped. Two examples are considered: one for editing captured walking motion and the other of direct motion synthesis for climbing stairs. The proposed methodology is very appropriate for interactive character animation.Item Extraction of Critical Points and Nets Based on Discrete Gradient Vector Field(Eurographics Association, 2002) De Floriani, Leila; Mesmoudi, Mohammed Mostefa; Danovaro, EmanueleIn this paper we address the problem of representing the topology of discrete scalar fields defined on triangulated domains. To this aim, we use the notion of discrete gradient vector field that we have introduced in [4] to classify the critical points of a scalar field defined over a two-dimensional domain that generalizes the nature of critical points in the differentiable case. Then we sketch an algorithm for extracting a critical net in the discrete case.Item Fast Volume Carving(Eurographics Association, 2002) Pyo, Soon Hyoung; Shin, Yeong GilIn recent years, the volumetric scene representation has been widely used in the fields of computer graphics and computer vision. In computer graphics, the representation is used to visualize and reconstruct 3D internal structures of 2D human-body medical data obtained from Magnetic Resonance Imaging (MRI) or Computed Tomography (CT). On the other hand, the volumetric representation is used to model 3D objects from a sequence of 2D images in computer vision. In both cases, eliminating some unnecessary part of the volumetric data is sometimes needed. For example, we need to remove skin or tissue which hides the target organ of human in volume rendering, or empty region of 3D objects being modeled in image-based modeling. In this paper, we propose a fast carving algorithm which can be applied in volume rendering and image-based modeling. The memory usage is minimized by using 1-bit field of a voxel to represent whether the voxel is carved or not. Our experiments show that we can carve out any part of the 5123 volume data in about a second. The carving speed is not affected by the complexity of objects.Item Feature interference in free form template matching(Eurographics Association, 2002) Song, Y.; Vergeest, J. S. M.; Horvath, I.Template matching is a useful method in the reconstruction of free form surfaces. In this paper, matching of free form surfaces with parameterized templates is studied with the emphasis on feature interference. By their definitions in 3- Dimensional space, free form features are introduced, analyzed and parameterized first. An optimization function based on a Hausdorff-like shape distance measuring method is proposed and applied as measuring method between the digitalized model surface and the parameterized feature template. The proposed method not only can fit isolated free form features, but also works when a feature is interfered by other free form features in some specified conditions. A series of numerical experiments have been conducted to demonstrate the proposed methods based on ACIS and Open Inventor. Fitting strategies are proposed as well.Item Flexible bump map capture from video(Eurographics Association, 2002) Paterson, James Alexander; Fitzgibbon, Andrew W.We extend recent techniques for the automated capture of surface normal maps or bump maps from real-world material samples. In contrast to recent systems, which have required cumbersome laboratory setups with careful calibration, we propose a moving-camera system which requires only one light source, rigidly attached to the camera. We describe a simple but accurate image-based calibration technique which allows the construction of an approximation to the standard photometric stereo setup. We show how to optimally estimate the system geometry during capture, and demonstrate that the accuracy of the new system is sufficient to allow normals to be computed.Item Frame-Coherent Stippling(Eurographics Association, 2002) Meruvia Pastor, Oscar E.; Strothotte, ThomasStippling is an artistic rendering technique where shading and texture is given by placing points or stipples on the canvas until the desired darkness is achieved. Computer-generated stippling has focused on producing high quality 2D renditions for print media, while stippling of 3D models in animation has received little attention. In this paper we present a technique to produce frame-coherent animations of 3D models using stippling as a rendering style. The problem for which we provide a solution is how to obtain an even distribution of stipples and at the same time ensure frame-to-frame coherence while shading changes over time. In our approach, particles are placed on the surface of the 3D model and adaptively rendered as stipples using OpenGL point primitives and the input model as a canvas. At each frame, the density of particles can be increased if necessary. Selection of particles during rendering takes into account the screen space projection of the edges of a polygon fan that surrounds the particles and the desired tone at the position of the particles. The rendering technique presented here can be applied to arbitrary polygonal meshes and can be extended to include grey scale textures, bump mapping and custom illumination models.Item From Textual Chats to Interest Groups in 3D Virtual Space(Eurographics Association, 2002) Masa, Michal; Zara, JiriWhile the textual chat is a highly popular tool for various kinds of social interactions, its extension to the visual three-dimensional domain remains almost untouched and without practical utilization yet. This paper discusses advantages and disadvantages of spatial virtual environment when used as a platform for connecting people and serving for social and cultural interaction. The differences between textual chat and interest groups in virtual reality are highlighted with the aim to overcome the gap between well-established chat technology and promising but still a bit exotic virtual reality approach. Theoretical analysis is followed by several examples taken from experimental setup.Item Function-defined shape node for VRML(Eurographics Association, 2002) Lai, Feng Min; Sourin, AlexeiThis paper describes how the web-based visualisation can be greatly improved using the function-based shape modelling technique. We propose the function-defined VRML shape node, which allows the content creators to describe any complex models with relatively small functions compared to the large-size polygonal mesh based VRML nodes. The design, the implementation details, and the application examples of the proposed node are discussed. The software is available for downloading from the project website.Item Geometric Simplification of Foliage(Eurographics Association, 2002) Remolar, Inmaculada; Chover, Miguel; Belmonte, Oscar; Ribelles, Jose; Rebollo, CristinaOne of the most important challenges in real-time rendering of outdoor scenes is the representation of vegetation. This is due to the vast amount of polygons that are used to model vegetable species. The present automatic simplification algorithms produce acceptable results in the trunks and the branches, but not in the foliage of a tree. After simplification with the existing methods, the trees seem to be less leafy. In this paper, a new automatic simplification algorithm for this part of the tree is presented, the Foliage Simplification Algorithm. It diminishes the number of polygons in the crown, while maintaining the appearance. It uses a new method, leaf collapse: two leaves disappear to create a new one. The leaves obtained after collapsing preserve an area similar to that of the collapsed leavesItem Hardware-Assisted Relief Texture Mapping(Eurographics Association, 2002) Fujita, Masahiro; Kanai, TakashiImage-Based Rendering by Warping (IBRW) creates three-dimensional scene by deforming several 2D images with depth information. Image-based rendering has an advantage compared to traditional polygon rendering that the rendering time is still constant even if a scene becomes complex. Relief texture mapping decomposes IBRWinto a very simple 1D image operation and a traditional texture mapping, which allows more effective computations. In this paper, we try to apply some hi-quality shading effects such as reflection mapping for relief texture mapping. Their effects can be realized by per-pixel shading technology of today’s graphics hardware. Our method for relief texture mapping allows fast and almost the same shading as well as traditional polygon rendering.
- «
- 1 (current)
- 2
- 3
- »