Libor Váša

Libor Váša
University of West Bohemia · Department of Computer Science and Engineering

PhD

About

49
Publications
6,517
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
545
Citations
Introduction
I am currently working as research assistant at Department of Computer Science and Engineering, University of West Bohemia. I am working on the topic of compressing surface models, surface animations with constant connectivity and motion capture data. I am also working on the problem of evaluation of the visual effects of lossy compression of graphical data.
Additional affiliations
February 2012 - March 2015
Technische Universität Chemnitz
Position
  • Research Assistant

Publications

Publications (49)
Article
Full-text available
Many algorithms have been proposed for the task of efficient compression of triangular meshes. Geometric properties of the input data are usually exploited to obtain an accurate prediction of the data at the decoder. Considerations on how to improve the prediction usually focus on its normal part, assuming that the tangential part behaves similarly...
Article
In this paper we present an extension of dynamic mesh compression techniques based on PCA. Such representation allows very compact representation of moving 3d surfaces, however it requires some side information to be transmitted along with the main data. The biggest part of this information is the PCA basis, and since the data can be encoded very e...
Article
Full-text available
There are multiple areas of computer graphics where triangular meshes are being altered in order to reduce their size or complexity, while attempting to preserve the original shape of the mesh as closely as possible. Recently, this area of research has been extended to cover even a dynamic case, i.e., surface animations which are compressed and sim...
Article
Surfaces evolving through time are hard to analyze without prior knowledge of the represented deforming shape. Topological noise introduced by inaccuracies during surface capture and reconstruction renders the estimation of time-consistent correspondence an ill-posed problem. It has previously been shown that this problem may be mitigated by tracki...
Article
Full-text available
The new generation 3D scanner devices have revolutionized the way information from 3D objects is acquired, making the process of scene capturing and digitization straightforward. However, the effectiveness and robustness of conventional algorithms for real scene analysis are usually deteriorated due to challenging conditions, such as noise, low res...
Chapter
Time varying meshes are more popular than ever as a representation of deforming shapes, in particular for their versatility and inherent ability to capture both true and spurious topology changes. In contrast with dynamic meshes, however, they do not capture the temporal correspondence, which (among other problems) leads to very high storage and pr...
Conference Paper
We present a general framework for teaching 3D imagination demanding topics using commonly available hardware for virtual reality (VR). Our software allows collaborating on 3D objects, interaction and annotation in a simple and intuitive manner. Students can follow the exposition from an arbitrary, naturally chosen point of view, and they interact...
Article
Full-text available
Reflectional symmetry is a potentially very useful feature which many real-world objects exhibit. It is instrumental in a variety of applications such as object alignment, compression, symmetrical editing or reconstruction of incomplete objects. In this paper, we propose a novel differentiable symmetry measure, which allows using gradient-based opt...
Article
Molecular dynamics simulations help to understand the complex behavior of molecules. The output of such a simulation describes the trajectories of individual atoms as snapshots of atom positions in time. Many compression schemes were developed to reduce the amount of data needed for storing long trajectories. This is achieved by limiting the precis...
Article
Full-text available
Random Sample Consensus is a powerful paradigm that was successfully applied in various contexts, including Location Determination Problem, fundamental matrix estimation and global 3D surface registration, where many previously proposed algorithms can be interpreted as a particular implementation of this concept. In general, a set of candidate tran...
Article
Full-text available
Curvature is an important geometric property in computer graphics that provides information about the character of object surfaces. The exact curvature can only be calculated for a limited set of surface descriptions. Most of the time, we deal with triangles, point sets or some other discrete representation of the surface. For those, curvature can...
Article
Full-text available
Laplacian mesh compression, also known as high‐pass mesh coding, is a popular technique for efficiently storing both static and dynamic triangle meshes that gained further recognition with the advent of perceptual mesh distortion evaluation metrics. Currently, the usual rule of thumb that drives the decision for a mesh compression algorithm is whet...
Chapter
Full-text available
Compression of 3D objects has been recently discussed mainly in the domain of 3D computer graphics. However, more and more applications demonstrate that the third dimension plays an important role also in the domain of modelling and streaming of geographical objects. This is especially true for 3D city models and their distribution via internet. De...
Conference Paper
Curvature plays an important role in computer graphics. It helps us to better understand surfaces of various objects. We often deal with a discrete geometry. However, the exact curvature can only be evaluated for analytical surfaces and not for discrete ones. Existing algorithms estimate curvature for discrete geometry with a certain precision. Mos...
Article
While it is usually not difficult to compute principal curvatures of a smooth surface of sufficient differentiability, it is a rather difficult task when only a polygonal approximation of the surface is available, because of the inherent ambiguity of such representation. A number of different approaches has been proposed in the past that tackle thi...
Article
Principal curvature is one of the defining features of surfaces studied in differential geometry. While well-defined and easy to evaluate for smooth surfaces, it cannot be evaluated exactly if the surface is represented by a polygon mesh, unless some special conditions apply. Nevertheless, estimating the curvature of a surface mesh is a crucial ste...
Conference Paper
Full-text available
Triangular meshes of high complexity are common when created by a 3D scanner device and must be reduced for further processing. The geodesic Poisson disk remeshing [FZ08] is a method that generates a simplified mesh with highly regular triangles at the cost of exorbitant computation time. In this paper we will outline a new approach to this techniq...
Article
In this paper, we present an algorithm for efficient encoding of triangle meshes. The algorithm preserves the local relations between vertices by encoding their Laplacian coordinates, while at the same time, it uses a hierarchy of additional vertex constraints that provides global rigidity and low absolute error, even for large meshes. Our scheme o...
Article
In this paper, we investigate the possibilities of efficient encoding of UV coordinates associated with vertices of a triangle mesh. Since most parametrization schemes attempt to achieve at least some level of conformality, we exploit the similarity of the shapes of triangles in the mesh and in the parametrization. We propose two approaches buildin...
Article
This paper addresses the problem of representing dynamic 3D meshes in a compact way, so that they can be stored and transmitted efficiently. We focus on sequences of triangle meshes with shared connectivity, avoiding the necessity of having a skinning structure. Our method first computes an average mesh of the whole sequence in edge shape space. A...
Article
Lossy compression of motion capture data can alleviate the problems of efficient storage and transmission by exploiting the redundancy and the superfluous precision of the data. When considering the acceptable amount of distortion, perceptual issues have to be taken into account. Current state of the art methods reduce the data rate required for hi...
Article
Full-text available
Almost all mesh processing procedures cause some more or less visible changes in the appearance of objects represented by polygonal meshes. In many cases, such as mesh watermarking, simplification or lossy compression, the objective is to make the change in appearance negligible, or as small as possible, given some other constraints. Measuring the...
Article
In computer graphics, triangle meshes are ubiquitous as a representation of surface models. Processing of this kind of data, such as compression or watermarking, often involves an unwanted distortion of the surface geometry. Advanced processing algorithms are continuously being proposed, aiming at improving performance (compression ratio, watermark...
Article
Full-text available
Mesh segmentation (clustering) is a useful tool, which improves compression performance. On the other hand, per-partes processing of meshes often leads to new types of artifacts -cracks and shifts on the borders between clusters. These artifacts are detected by both, Human Visual System (HVS) and perceptually-motivated dis-tortion metrics. In this...
Article
During the last decade many algorithms for compressing 3D animations represented by sequences of triangular meshes have been proposed. Most of these algorithms are lossy in their nature, i.e. the reconstructed data do not exactly match the algorithm input.Quite surprisingly, most of the existing algorithms mainly use only general compression techni...
Article
Development of geometry data compression techniques in the past years has been limited by the lack of a metric with proven correlation with human perception of mesh distortion. Many algorithms have been proposed, but usually the aim has been to minimise mean squared error, or some of its derivatives. In the field of dynamic mesh compression, the si...
Conference Paper
Full-text available
Advances in both graphics hardware and scanning technology have allowed for retrieving and rendering complex 3D models with thousands of vertices. With the recent popularity gain of interactive web applications, the data size is beginning to be the tightest bottleneck, especially for detailed 3D animations. The MPEG-4 standard was recently suppleme...
Article
Full-text available
The task of dynamic mesh compression seeks to find a compact representation of a surface animation, while the artifacts introduced by the representation are as small as possible. In this paper, we present two geometric predictors, which are suitable for PCA-based compression schemes. The predictors exploit the knowledge about the geometrical meanin...
Article
Full-text available
We present a new approach to dynamic mesh compression, which combines compression with simplification to achieve improved compression results, a natural support for incremental transmission and level of detail. The algorithm allows fast progressive transmission of dynamic 3D content. Our scheme exploits both temporal and spatial coherency of the in...
Conference Paper
3D triangle meshes are a common form for representing the geometry of static and dynamic 3D objects. They are employed already in many areas, e.g. e-commerce, video games, online museums, CGI or 3D animated films, etc. Static triangle meshes represent only a piecewise linear approximation of complex 3D objects. As a consequence the approximation er...
Conference Paper
Full-text available
Compression of 3D mesh animations is a topic that has received increased attention in recent years, due to increasing capabilities of modern processing and displaying hardware. In this paper we present an improved approach based on known techniques, such as principal component analysis (PCA) and EdgeBreaker, which allows efficient encoding of highl...
Conference Paper
Full-text available
A new approach to comparison of dynamic meshes based on Hausdorff distance is presented along with examples of application of such metric. The technique presented is based on representation of a 3D dynamic mesh by a 4D static tetrahedral mesh. Issues concerning space-time relations, mesh consistency and distance computation are addressed, yielding...
Article
Full-text available
A quick overview of preprocessing performed by digital still cameras is given along with a brief introduction to spatial-domain Super-Resolution methods, i.e. spatial resolution enhan-cement methods that create one high-resolution image from a series of low-resolution images shifted by a sub-pixel distance. An improvement applicable to some of exis...
Conference Paper
Full-text available
The growth of computational power of contemporary hardware causes technologies working with 3D-data to expand. Examples of the use of this kind of data can be found in geography or gaming industry. 3D-data may not be only static, but also dynamic. One way of animated 3D-data representation is expressing them by ”dynamic triangle mesh”. This kind o...
Conference Paper
Full-text available
This paper proposes a method of rate-distortion optimisation of an algorithm for compressing dynamic 3D triangle meshes. Although many articles regarding compression methods for this kind of data have been published in the last decade, the problem of rate-distortion optimisation has only been addressed by a very few of them. An exhaustive search me...
Article
Full-text available
A brief introduction to spatial-domain Super-Resolution methods, i.e. spatial resolution enhancement methods that create one high-resolution image from a series of low- resolution images shifted by a sub-pixel distance, is given. An improvement applicable to some of existing Super- Resolution methods is presented. Principles of digital photography...