Yiorgos Chrysanthou

Yiorgos Chrysanthou
University of Cyprus · Department of Computer Science

PhD in Computer Graphics, QMW, Univ. of London

About

129
Publications
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Introduction
Yiorgos Chrysanthou currently works at the Department of Computer Science, University of Cyprus. Yiorgos does research in Computer Graphics.

Publications

Publications (129)
Article
Recent advancements in crowd simulation unravel a wide range of functionalities for virtual agents, delivering highly‐realistic, natural virtual crowds. Such systems are of particular importance to a variety of applications in fields such as: entertainment (e.g., movies, computer games); architectural and urban planning; and simulations for sports...
Conference Paper
Full-text available
Folk dancing is a key aspect of intangible cultural heritage that often reflects the socio-cultural and political influences prevailing in different periods and nations; each dance produces a meaning, a story with the help of music, costumes and dance moves. It has been transmitted from generation to generation, and to different countries, mainly d...
Article
Full-text available
Synthesizing human motion with a global structure, such as a choreography, is a challenging task. Existing methods tend to concentrate on local smooth pose transitions and neglect the global context or the theme of the motion. In this work, we present a music-driven motion synthesis framework that generates long-term sequences of human motions whic...
Chapter
This paper presents a pilot study on the evaluation of instruments for data gathering for an epistemic game development competition for high school students. The initial results show that a significant percentage of the students who participated in the competition appear to exhibit a skillset of professional attitude, software-related knowledge, an...
Preprint
Full-text available
Data-driven character animation techniques rely on the existence of a properly established model of motion, capable of describing its rich context. However, commonly used motion representations often fail to accurately encode the full articulation of motion, or present artifacts. In this work, we address the fundamental problem of finding a robust...
Preprint
Full-text available
Synthesizing human motion with a global structure, such as a choreography, is a challenging task. Existing methods tend to concentrate on local smooth pose transitions and neglect the global context or the theme of the motion. In this work, we present a music-driven motion synthesis framework that generates long-term sequences of human motions whic...
Conference Paper
Full-text available
In this paper, we have designed and developed a virtual dance museum to provide the technological tools that allow for widely educating the public, most specifically the youngest generations, about the story, costumes, music, and history of our dances. The holistic documentation of our intangible cultural heritage creations is a critical necessity...
Article
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We present an algorithm for the segmentation of images into background and foreground regions. The proposed algorithm utilizes a physically based formulation of scene appearance which explicitly models the formation of shadows originating from color light sources. This formulation enables a probabilistic model to distinguish between shadows and for...
Preprint
Full-text available
Contemporary discourse points to the central role that heritage plays in the process of enabling groups of various cultural or ethnic background to strengthen their feeling of belonging and sharing in society. Safeguarding heritage is also valued highly in the priorities of the European Commission. As a result, there have been several long-term ini...
Article
This paper presents a pilot study on the evaluation of instruments for data gathering for an epistemic game development competition for high school students. The initial results show that a significant percentage of the students who participated in the competition appear to exhibit a skillset of professional attitude, software-related knowledge, an...
Conference Paper
Full-text available
‘‘Humans at rest tend to stay at rest. Humans in motion tend to cross the road – Isaac Newton.” Even though this response is meant to be a joke to indicate the answer is quite obvious, this important feature of real world crowds is rarely considered in simulations. Answering this question involves several things such as how agents balance between r...
Article
Full-text available
Folk dances often reflect the socio-cultural influences prevailing in different periods and nations; each dance produces a meaning, a story with the help of music, costumes and dance moves. However, dances have no borders; they have been transmitted from generation to generation, along different countries, mainly due to movements of people carrying...
Article
Full-text available
Many analysis tasks for human motion rely on high-level similarity between sequences of motions, that are not an exact matches in joint angles, timing, or ordering of actions. Even the same movements performed by the same person can vary in duration and speed. Similar motions are characterized by similar sets of actions that appear frequently. In t...
Article
Full-text available
Synthesizing human motions from existing motion capture data is the approach of choice in most applications requiring high- quality visual results. Usually to synthesize motion, short motion segments are concatenated into longer sequences by finding transitions at points where character poses are similar. If similarity is only a measure of posture...
Conference Paper
When designing environments in Immersive Virtual Reality, virtual humans are often used to enrich them. In this paper, we research factors arising by the use of virtual crowds that may instigate more user participation in virtual reality scenarios. In particular, we examine whether implementing responsive virtual crowd behaviors toward the particip...
Article
Full-text available
Inverse kinematics (IK) is the use of kinematic equations to determine the joint parameters of a manipulator so that the end effector moves to a desired position; IK can be applied in many areas, including robotics, engineering, computer graphics and video games. In this survey, we present a comprehensive review of the IK problem and the solutions...
Chapter
Object recognition and tracking is a common task in video processing with multiple applications including surveillance, security, industrial inspection, medicine, and more. Recognition and tracking accuracy can drop significantly when the scene dynamic range exceeds that of common camera sensors, which may lead to decreased tracking accuracy. The p...
Conference Paper
Full-text available
Motion capture technology has enabled the acquisition of high quality human motions for animating digital characters with extremely high fidelity. However, despite all the advances in motion editing and synthesis, it remains an open problem to modify pre-captured motions that are highly expressive, such as contemporary dances, for stylization and e...
Chapter
Computer generated crowds are nowadays commonly used in films, video games, on-line communities and virtual environment applications. Realistic simulation of such crowds is an important factor in the level of user immersion and the value of the conclusions one can draw from these simulations. Over the past twenty years, the field of computer graphi...
Chapter
Crowds are an important part of our daily lives. We are constantly surrounded by and are part of crowds; in streets, workplaces, shopping malls, football stadiums, concerts, etc. The presence and the dynamics of crowds greatly affect the ambiance of any given scene. Computer generated crowds have become an important feature of modern applications a...
Article
This study examines attributes of virtual human behavior that may increase the plausibility of a simulated crowd and affect the user's experience in Virtual Reality. Purpose-developed experiments in both Immersive and semi-Immersive Virtual Reality systems queried the impact of collision and basic interaction between real-users and the virtual crow...
Article
Full-text available
Forward and Backward Reaching Inverse Kinematics (FABRIK) is a recent iterative inverse kinematics solver that became very popular because of its simplicity, convergence speed and control performance, especially in models with multiple end effectors. In this paper, we extend and/or adjust FABRIK to be used in problems with leaf joints and closed-lo...
Conference Paper
Full-text available
Η τεχνολογία motion capture (mocap) είναι μια αποτελεσματική μέθοδος τρισδιάστατης (3Δ) ψηφιακής καταγραφής κίνησης, και η χρήση της αυξάνεται ολοένα και περισσότερο στον τομέα της διατήρησης και διάδοσης της Άυλης Πολιτιστικής Κληρονομιάς (ΑΠΚ). Αν και τα δεδομένα που καταγράφονται μπορούν από τεχνικής άποψης να είναι πολύ υψηλής ποιότητας, στην π...
Article
Full-text available
Motion capture (mocap) technology is an efficient method for digitizing art performances, and is becoming increasingly popular in the preservation and dissemination of dance performances. Although technically the captured data can be of very high quality, dancing allows stylistic variations and improvisations that cannot be easily identified. The m...
Article
Full-text available
The increasing availability of large motion databases, in addition to advancements in motion synthesis, has made motion indexing and classification essential for better motion composition. However, in order to achieve good connectivity in motion graphs, it is important to understand human behaviour; human movement though is complex and difficult to...
Conference Paper
Full-text available
In the area of computer graphics the design of hardware and software has primarily been driven by the need to achieve maximum performance. Energy efficiency was usually neglected, assuming that a stable always-on power source was available. However, the advent of the mobile era has brought into question these ideas and designs in computer graphics...
Conference Paper
Full-text available
Motion capture (mocap) technology is an efficient method for digitizing art-performances, and it is becoming a popular method for the preservation and dissemination of dances. However, stylistic variations of human motion are difficult to measure and cannot be directly extracted from the motion capture data itself. In this work, we present a framew...
Conference Paper
Full-text available
Motion capture techniques are becoming a popular method for digitizing folk dances for preservation and dis-semination. Although technically the captured data can be of very high quality, folk dancing, in contrast to choreographed performances, allow for stylistic variations and improvisations that cannot be easily captured by the data themselves....
Article
We present a novel approach for analyzing the quality of multi-agent crowd simulation algorithms. Our approach is data-driven, taking as input a set of user-defined metrics and reference training data, either synthetic or from video footage of real crowds. Given a simulation, we formulate the crowd analysis problem as an anomaly detection problem a...
Article
The concept and methods of user experience (UX) are gaining momentum in the game industry. Designers and educational practitioners aim to provide rich and effective user experience through serious educational games. Nevertheless several phenomena that delineate the complex issue of UX in serious gaming remain unexplored. This empirical study sheds...
Article
Humans are emotional beings and their feelings influence the way they perform and interact with computers. One of the most expressive modality for humans is body posture and movement that has lately started to receive attention from researchers in the use for emotion recognition. This survey outlines the findings relating to the area of body emotio...
Article
We present a data-driven method for the real-time synthesis of believable steering behaviours for virtual crowds. The proposed method interlinks the input examples into a structure we call the perception-action graph (PAG) which can be used at run-time to efficiently synthesize believable virtual crowds. A virtual character's state is encoded using...
Article
Full-text available
Cultural Heritage Cyprus has a long and rich history of dance tradition which unfortunately, year after year, tends to be forgotten; thus, it is our duty to help documenting and disseminating our dance heritage to the younger generations. In this work, we aim to preserve the Cypriot folk dance heritage, creating a state-of-the-art publicly accessib...
Conference Paper
Full-text available
There has been an increasing use of pre-recorded motion capture data for animating virtual characters and synthesising different actions; it is although a necessity to establish a resultful method for indexing, classifying and retrieving motion. In this paper, we propose a method that can automatically extract motion qualities from dance performanc...
Conference Paper
Full-text available
Recently, there has been an increasing use of pre-recorded motion capture data, making motion indexing and classification essential for animating virtual characters and synthesising different actions. In this paper, we use a variety of features that encode characteristics of motion using the Body, Effort, Shape and Space components of Laban Movemen...
Conference Paper
Full-text available
Exergames do not have the capacity to detect whether the players are really enjoying the game-play. The games are not intelligent enough to detect significant emotional states and adapt accordingly in order to offer a better user experience for the players. We pro- pose a set of body motion features, based on the Effort component of Laban Movement...
Conference Paper
Full-text available
When preparing high dynamic range images (HDR) for dis- play on standard monitors, it is often necessary to make a choice between global and local tone mapping. While the former is simple and efficient, it may fail to reproduce details in high contrast image regions. Although, the latter can better reproduce details in such regions, it often comes...
Article
Full-text available
Interactive technologies are employed in museums to enhance the visitors’ experience and help them learn in more authentic ways. Great amounts of time and money and many man-hours of hard work have been spent. But do such systems indeed achieve their goals? Do they contribute to a greater user experience (UX) and learning effectiveness? In this pap...
Article
The concept and methods of user experience (UX) are gaining momentum in the game industry. Designers and educational practitioners aim to provide rich and effective user experience through serious educational games. Nevertheless several phenomena that delineate the complex issue of UX in serious gaming remain unexplored. This empirical study sheds...
Conference Paper
Full-text available
This paper presents the first stages of a larger project concerning the study and realization of a 3D interactive environment of everyday life in 19th century Nicosia. The presented study involves the recreation of the built urban environment (i.e. the architecture of the city) based on historic and archival information taken from the first Land Re...
Conference Paper
Full-text available
In this article an initiative to preserve the Cypriot folk dance heritage is reported. The project aims to create a publicly accessible digital archive of folk dances that does not only include video recordings, commonly used to document dance performances. In addition to rare video material held by local cultural institutions, state-of-the-art mot...
Conference Paper
Full-text available
Large resolution High Dynamic Range (HDR) textures/images are becoming common in computer graphics applications. However, it is still a prohibitive task to perform on them a filtering step such as tone mapping in real-time. We introduce a novel technique called Selective Tone Mapper (STM) for accelerating the tone mapping step on large resolution H...
Article
The visualization system of large-scale crowd simulations should scale up with both the number of visuals (views of the virtual world) and the number of agents displayed in each visual. Otherwise, we could have large scale crowd simulations where only a small percentage of the population is displayed. Several approaches have been proposed in order...
Article
Full-text available
Given a noisy and incomplete point set, we introduce a method that simultaneously recovers a set of locally fitted primitives along with their global mutual relations. We operate under the assumption that the data corresponds to a man-made engineering object consisting of basic primitives, possibly repeated and globally aligned under common relatio...
Conference Paper
Full-text available
Museums research new ways to offer positive experience to the visitors and encourage them to return, using modern communication and learning tools. To the effect, technologically advanced interactive ICT systems, are placed in modern-day museums. In this paper we describe and compare six different types of museum exhibits, one traditional and five...
Article
Abstract Many times, even if a crowd simulation looks good in general, there could be some specific individual behaviors which do not seem correct. Spotting such problems manually can become tedious, but ignoring them may harm the simulation's credibility. In this paper we present a data-driven approach for evaluating the behaviors of individuals w...
Article
Computation of illumination with soft-shadows from all-frequency environment maps, is a computationally expensive process. Use of pre-computation add the limitation that receiver's geometry must be known in advance, since Irradiance computation takes into account the receiver's normal direction. We propose a method that using a new notion that we i...
Conference Paper
Full-text available
We present a novel GPU-based method for accelerating the visibility function computation of the lighting equation in dynamic scenes composed of rigid objects. The method pre-computes, for each object in the scene, the visibility and normal information, as seen from the environment, onto the bounding sphere surrounding the object and encodes it into...
Conference Paper
Full-text available
Modern-day museums employ technologically advanced methods and equipment to facilitate the dissemination of information and education of their visitors. Such a system is installed at the Leventis Municipal Museum in Nicosia. An interactive application that runs on a multi-touch table allows the user to navigate through a 3D representation of the fo...
Conference Paper
Full-text available
Crowd steering algorithms generally use empirically selected stimuli to determine when and how an agent should react. These stimuli consist of information from the environment that potentially influence behavior such as an agent’s visual perception, its neighboring agents state and actions, locations of nearby obstacles, etc. The various different...
Conference Paper
Full-text available
Modern-day museums employ technologically advanced methods and equipment to facilitate the dissemination of information and education of their visitors. Such a system is installed at the Leventis Municipal Museum in Nicosia. An interactive application that runs on a multi-touch table allows the user to navigate through a 3D representation of the fo...
Presentation
Presentation of basic and applied research conducted by the research group.
Conference Paper
Full-text available
There are various techniques for simulating crowds, however, in most cases the quality of the simulation is measured by examining its “look-and-feel”. Even if the aggregate movement of the crowd looks natural from afar, the behaviors of individuals might look odd when examined more closely. In this paper we present a data-driven approach for evalua...
Conference Paper
Full-text available
In this paper we present a data-driven approach for fitting behaviors to simulated pedestrian crowds. Our method annotates agent trajectories, generated by any crowd simulator, with action-tags. The aggregate effect of animating the agents according to the tagged trajectories enhances the impression that the agents are interacting with one another...