A Data‐Driven Framework for Visual Crowd Analysis

Panayiotis Charalambous, Ioannis Karamouzas, Stephen J. Guy, Yiorgos Chrysantho

Computer Graphics Forum, vol. 33, no. 7, pp. 41-50, Oct 2014

Presented at: Pacific Graphics 2014

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 and exploit state-of-the-art outlier detection algorithms to address it. To that end, we introduce a new framework for the visual analysis of crowd simulations. Our framework allows us to capture potentially erroneous behaviors on a per-agent basis either by automatically detecting outliers based on individual evaluation metrics or by accounting for multiple evaluation criteria in a principled fashion using Principle Component Analysis and the notion of Pareto Optimality. We discuss optimizations necessary to allow real-time performance on large datasets and demonstrate the applicability of our framework through the analysis of simulations created by several widely-used methods, including a simulation from a commercial game.

DOI paper video project page

Motion Analysis for Folk Dance Evaluation

Andreas Aristidou, Efstathios Stavrakis, Yiorgos Chrysanthou

Presented at: 12th EUROGRAPHICS Workshop on Graphics and Cultural Heritage (GCH'14), pages 55-64, Darmstadt, Germany, Oct 2014

DOI paper bibtex

Automatic Emotion Recognition Based on Body Movement Analysis: A Survey

Haris Zacharatos, Christos Gatzoulis, Yiorgos Chrysanthou

IEEE Computer Graphics and Applications 34.6 (2014), pp. 35–45, Sep 2014


The PAG Crowd: A Graph Based Approach for Efficient Data‐Driven Crowd Simulation.

Panayiotis Charalambous, Yiorgos Chrysanthou.

Computer Graphics Forum, vol. 33, no. 8, pp. 95-108, Jun 2014

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 a temporal representation, the Temporal Perception Pattern (TPP). The graph nodes store groups of similar TPPs whereas edges connecting the nodes store actions (trajectories) that were partially responsible for the transformation between the TPPs. The proposed method is being tested on various scenarios using different input data and compared against a nearest neighbours approach which is commonly employed in other data‐driven crowd simulation systems. The results show up to an order of magnitude speed‐up with similar or better simulation quality.

DOI paper video project page

Cypriot Intangible Cultural Heritage: Digitizing Folk Dances

Andreas Aristidou, Efstathios Stavrakis, Yiorgos Chrysanthou

Cyprus Computer Society journal, Issue 25, pages 42-49, Apr 2014

We aim to preserve the Cypriot folk dance heritage, creating a state-of-the-art publicly accessible digital archive of folk dances. Our dance library, apart from the rare video materials that are commonly used to document dance performances, utilises three dimensional motion capture technologies to record and archive high quality motion data of expert dancers.

paper bibtex project page

Simulating Heterogeneous Crowds With Interactive Behaviors

Mubbasir Kappadia, Nuria Pelechano, Stephen Guy, Jan Allbeck, Yiorgos Chrysanthou

Presented at: Tutorial at Eurographics’14, Apr 2014


Feature extraction for human motion indexing of acted dance performances

Andreas Aristidou, Yiorgos Chrysanthou

Presented at: 9th International Conference on Computer Graphics Theory and Applications (GRAPP'14), pages 277-287, Lisbon, Portugal, Jan 2014

DOI paper bibtex

Motion indexing of different emotional states using LMA components

Andreas Aristidou, Yiorgos Chrysanthou

Presented at: SIGGRAPH Asia Technical Briefs (SA’13), ACM, New York, USA, 21:1-21:4, Nov 2013

DOI paper bibtex

Emotion Recognition for Exergames using Laban Movement Analysis

Haris Zacharatos, Christos Gatzoulis, Yiorgos Chrysanthou, Andreas Aristidou

Presented at: ACM Motion in Games (MIG'13), Dublin, Ireland, Sep 2013

DOI paper bibtex

Learning Through Multi-Touch Interfaces in Museum Exhibits: an Empirical Investigation

Panagiotis Zaharias, Despina Michael, Yiorgos Chrysanthou

Educational Technology & Society 16.3 (2013), pp. 374–384, Sep 2013


Marker Prediction and Skeletal Reconstruction in Motion Capture Technology

Andreas Aristidou, Yiorgos Chrysanthou

Tech. rep. UCY-CS-TR-13-2. University of Cyprus, Aug 2013

paper bibtex

Selective Local Tone Mapping

Alessandro Artusi, Ahmet Oguz Akyuz, Benjamin Roch, Despina Michael, Yiorgos Chrysanthou, Alan Chalmers

Presented at: IEEE International Conference on Image Processing (ICIP). IEEE. 2013, pp. 2309– 2313, Jan 2013

The Cyprus Food and Nutrition Virtual Museum. An Attempt to Preserve and Disseminate Knowledge about Past Foodways and Controversial Issues Regarding the Revival of Traditional Food

Antonia Matalas, Chrystaleni Lazarou, Chrysanthou Yiorgos

ed. by Lysaght P. Lund, Sweden: Lund University, Chap. The Return to Traditional Food, pp. 146–151, Jan 2013

paper project page

Affect Recognition during Active Game Playing based on Posture Skeleton Data

Haris Zacharatos, Christos Gatzoulis, Yiorgos Chrysanthou

Presented at: International Conference on Computer Graphics Theory and Applications. pp. 419– 422, Jan 2013


Reconstruction of everyday life in 19th century Nicosia

Panayiotis Charalambous, Hesperia Iliadou, Charalambos Apostolou, Yiorgos Chrysanthou

Presented at: 4th international conference on Progress in Cultural Heritage Preservation (EuroMed'12), Limassol, Cyprus, Nov 2012

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 Registry documentations taking place on the island at the end of the Ottoman era by British engineers.

DOI paper project page