Andreas Alexandros VasilakisAthens University of Economics and Business | AUEB · Department of Informatics
Andreas Alexandros Vasilakis
Postdoc Researcher
About
31
Publications
7,945
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196
Citations
Citations since 2017
Introduction
Hi, I am Andreas A. Vasilakis and I am a postdoctoral fellow in the Department of Informatics of the Athens University of Economics and Business as well as an adjunct lecturer in the Department of Computer Science and Engineering of Ioannina University. My research interests include interactive graphics, geometry processing techniques and real-time rendering algorithms
Skills and Expertise
Additional affiliations
October 2020 - present
Position
- Lecturer
Description
- Teaching two elective courses of the undergraduate syllabus: (a) Advanced Computer Graphics and (b) VR/AR/MR
April 2014 - January 2016
September 2008 - June 2014
Publications
Publications (31)
Photorealistic computer graphics is ubiquitous today, with applications that include entertainment—notably, movies and video games; product design; and architecture. Physically based techniques attempt to simulate reality; that is, they use principles of physics to model the interaction of light and matter. Over the past decade, physically-based ap...
![Hybrid transparency [8] combines an accurate composition of the “core”...](publication/361687928/figure/fig2/AS:11431281084473019@1663206872972/Hybrid-transparency8-combines-an-accurate-composition-of-the-core-fragment-samples_Q320.jpg)
Correctly compositing transparent fragments is an important and long-standing open problem in real-time computer graphics. Multifragment rendering is considered a key solution to providing high-quality order-independent transparency at interactive frame rates. To achieve that, practical implementations severely constrain the overall memory budget b...
Rayground is a novel online framework for fast prototyping and interactive demonstration of ray tracing algorithms. It aims to set the ground for the online development of ray-traced visualization algorithms in an accessible manner for everyone, stripping off the mechanics that get in the way of creativity and the understanding of the core concepts...
This chapter introduces WebRays, a GPU-accelerated ray intersection engine for the World Wide Web. It aims to offer a flexible and easy-to-use programming interface for robust and high-performance ray intersection tests on modern browsers. We cover design considerations, best practices, and usage examples for several ray tracing tasks.
We introduce a simplification method for light probe configurations that preserves the indirect illumination distribution in scenes with diverse lighting conditions. An iterative graph simplification algorithm discards the probes that, according to a set of evaluation points, have the least impact on the global light field. Our approach is simple,...
Spatial queries to infer information from the neighborhood of a set of points are very frequently performed in rendering and geometry processing algorithms. Traditionally, these are accomplished using radius and k-nearest neighbors search operations, which utilize kd-trees and other specialized spatial data structures that fall short of delivering...
Ray tracing on the GPU has been synergistically operating alongside rasterisation in interactive rendering engines for some time now, in order to accurately capture certain illumination effects. In the same spirit, in this paper, we propose an implementation of progressive photon mapping entirely on the rasterisation pipeline, which is agnostic to...
Lighting plays a very important role in interior design. However, in the specific problem of furniture layout recommendation, illumination has been either neglected or addressed with empirical or very simplified solutions. The effectiveness of a particular layout in its expected task performance can be greatly affected by daylighting and artificial...
In this paper, we present Rayground; an online, interactive education tool for richer in-class teaching and gradual self-study, which provides a convenient introduction into practical ray tracing through a standard shader-based programming interface. Setting up a basic ray tracing framework via modern graphics APIs, such as DirectX 12 and Vulkan, r...
In the past few years, advances in graphics hardware have fuelled an explosion of research and development in the field of interactive and real-time rendering in screen space. Following this trend, a rapidly increasing number of applications rely on multifragment rendering solutions to develop visually convincing graphics applications with dynamic...
Background
Frailty is a common clinical syndrome in ageing population that carries an increased risk for adverse health outcomes including falls, hospitalization, disability, and mortality. As these outcomes affect the health and social care planning, during the last years there is a tendency of investing in monitoring and preventing strategies. Al...
We introduce a novel approach to support fast and efficient lossy compression of arbitrary animation sequences ideally suited for real-time scenarios, such as streaming and content creation applications, where input is not known a priori and is dynamically generated. The presented method exploits temporal coherence by altering the principal compone...
Successfully predicting visual attention can significantly improve many aspects of computer graphics and games. Despite the thorough investigation in this area, selective rendering has not addressed so far fragment visibility determination problems. To this end, we present the first ''selective multi-fragment rendering'' solution that alters the cl...
In computer graphics, animation compression is essential for efficient storage, streaming and reproduction of animated meshes. Previous work has presented efficient techniques for compression using skinning transformations to derive the animated mesh from a reference pose. We present a pose-to-pose approach to skinning animated meshes by observing...
We introduce a novel approach to image-space ray tracing ideally suited for the photorealistic synthesis of fully dynamic environments at interactive frame rates. Our method, designed entirely on the rasterization pipeline, alters the acceleration data structure construction from a per-fragment to a per-primitive basis in order to simultaneously su...
We introduce a generic method for interactive ray tracing, able to support complex and dynamic environments, without the need for precomputations or the maintenance of additional spatial data structures. Our method, which relies entirely on the rasterization pipeline, stores fragment information for the entire scene on a multiview and multilayer st...
Depth-sorted fragment determination is fundamental for a host of image-based techniques which simulates complex rendering effects. It is also a challenging task in terms of time and space required when rasterizing scenes with high depth complexity. When low graphics memory requirements are of utmost importance, k-buffer can objectively be considere...
In this work, we investigate an efficient approach to treat fragment racing when computing k-nearest fragments. Based on the observation that knowing the depth position of the k-th fragment we can optimally find the k-closest fragments, we introduce a novel fragment culling component by employing occupancy maps.Without any softwarere design, the pr...
In the last decade, significant research has been conducted for addressing the problem of multi-fragment rendering from different perspectives. While the hardware-accelerated A-buffer is the dominant structure for holding multiple fragments via per-pixel linked lists, several variants have been proposed to alleviate the cost of excessive allocation...
![Figure 9: Merging (d),(e) the global segmentations from [GFW*06] of...](profile/Andreas-Vasilakis/publication/262772488/figure/fig12/AS:281730469646337@1444181186260/Merging-d-e-the-global-segmentations-from-GFW06-of-a-b-two-individual-mesh_Q320.jpg)
We present a complete approach to efficiently deriving a varying level-of-detail segmentation of arbitrary animated objects. An over-segmentation is built by combining sets of initial segments computed for each input pose, followed by a fast progressive simplification which aims at preserving rigid segments. The final segmentation result can be eff...
k-buffer facilitates novel approaches to multi-fragment rendering and visualization for developing interactive applications on the GPU. Various alternatives have been proposed to alleviate its memory hazards and to avoid completely or partially the necessity of geometry pre-sorting. However, that came with the burden of excessive memory allocation...
Many applications require operations on multiple fragments that result from ray casting at the same pixel location. To this end, several approaches have been introduced that process for each pixel one or more fragments per rendering pass, so as to produce a multi-fragment effect. However, multi-fragment rasterization is susceptible to flickering ar...
We explore different semantics for the solid defined by a self-crossing surface (immersed sub-manifold). Specifically, we introduce rules for the interior/exterior classification of the connected components of the complement of a self-crossing surface produced through a continuous deformation process of an initial embedded manifold. We propose effi...
This work introduces S-buffer, an efficient and memory-friendly gpu-accelerated A-buffer architecture for multifragment rendering. Memory is organized into variable contiguous regions for each pixel, thus avoiding limitations set in linked-lists and fixed-array techniques. S-buffer exploits fragment distribution for precise allocation of the needed...
Efficient capturing of the entire topological and geometric information of a 3D scene is an important feature in many graphics applications for rendering multi-fragment effects. Example applications include order independent transparency, volume rendering, CSG rendering, trimming, and shadow mapping all of which require operations on more than one...
In this paper, we present a skeletal rigid skinning approach. First, we describe a skeleton extraction technique that produces refined skeletons appropriate for animation from decomposed character models. Then, to avoid the artifacts generated in previous skinning approaches and the associated high training costs, we develop an efficient and robust...
Skeleton-based skinning is widely used for realistic animation of complex characters defining mesh movement as a function of the underlying skeleton. In this paper, we propose a new robust skeletal animation
framework for 3D articulated models. The contribution of this work is twofold. First, we present refinement techniques for improving skeletal...
Skeleton-based skinning is widely used for realistic animation of complex characters defining mesh move- ment as a function of the underlying skeleton. In this paper, we propose a new robust skeletal animation framework for 3D articulated models. The contribution of this work is twofold. First, we present refinement techniques for improving skeleta...
In this paper, we present a novel skeletal rigid skinning approach. First, we introduce a skeleton extraction technique that produces refined skeletons appropriate for animation from decomposed solid models. Then, to avoid the artifacts generated in previous rigid skinning approaches and the associated high training costs, we develop an efficient a...
In computer animation, key-frame compression is essential for efficient storage, processing and reproduction of animation sequences. Previous work has presented efficient techniques for compression using affine or rigid trans-formations to derive the skin from the initial pose using a relatively small number of control joints. We present a novel po...
Projects
Projects (2)
Rayground is an online framework for rapid prototyping of algorithms based on the ray tracing paradigm. Rayground is platform-independent, based on open-source technologies and available to everyone through the www.rayground.com portal. We identify two distinct components in Rayground. The first component is the website, which acts as an online library of ray tracing projects and offers an integrated development environment (IDE) for interactive demonstration and/or prototyping. It has the potential to function as a hub for the graphics community as ray tracing ideas and methods become more widespread. The second component is WebRays, the ray tracing engine that accelerates ray-geometry intersections using the WebGL2 graphics application programming interface (API). The core technology behind the engine is decoupled from Rayground’s programming model and utilizes an open-source general-purpose ray-geometry intersection engine on the Web via a JavaScript API, backed by acceleration data structures.
Research and development on interactive global illumination by exploiting novel machine learning methods.
