Self-similarity Analysis for Motion Capture Cleaning

Andreas Aristidou, Daniel Cohen-Or, Jessica K. Hodgins, Ariel Shamir

Computer Graphics Forum, 37(2), 2018.

Proceedings of Eurographics 2018.

Our method automatically analyzes mocap sequences of closely interacting performers based on self-similarity. We define motion-words consisting of short-sequences of joints transformations, and use a time-scale invariant similarity measure that is outlier-tolerant to find the KNN. This allows detecting abnormalities and suggesting corrections.

[DOI] [paper] [video] [bibtex] [project page]

Inverse Kinematics Techniques in Computer Graphics: A Survey

Andreas Aristidou, Joan Lasenby, Yiorgos Chrysanthou, Ariel Shamir

Computer Graphics Forum, 2017.

To be presented at Eurographics 2018 (STAR paper).

In this survey, we present a comprehensive review of the IK problem and the solutions developed over the years from the computer graphics point of view. The most popular IK methods are discussed with regard to their performance, computational cost and the smoothness of their resulting postures, while we suggest which IK family of solvers is best suited for particular problems. Finally, we indicate the limitations of the current IK methodologies and propose future research directions.

[DOI] [paper] [bibtex] [project page]

Style-based Motion Analysis for Dance Composition

Andreas Aristidou, Efstathios Stavrakis, Margarita Papaefthimiou, George Papagiannakis, Yiorgos Chrysanthou

The Visual Computer, 2017.

This work presents a motion analysis and synthesis framework, based on Laban Movement Analysis, that respects stylistic variations and thus is suitable for dance motion synthesis.

[DOI] [paper] [video] [bibtex] [project page]

Emotion Control of Unstructured Dance Movements

Andreas Aristidou, Qiong Zeng, Efstathios Stavrakis, KangKang Yin, Daniel Cohen-Or, Yiorgos Chrysanthou, Baoquan Chen

ACM SIGGRAPH/ Eurographics Symposium on Computer Animation, SCA'17. Eurographics Association, July, 2017.

We present a motion stylization technique suitable for highly expressive mocap data, such as contemporary dances. The method varies the emotion expressed in a motion by modifying its underlying geometric features. Even non-expert users can stylize dance motions by supplying an emotion modification as the single parameter of our algorithm.

[DOI] [paper] [video] [bibtex] [project page]

Hand Tracking with Physiological Constraints

Andreas Aristidou

The Visual Computer, 34 (2): 213-228, 2018.

We present a simple and efficient methodology for tracking and reconstructing 3D hand poses. Using an optical motion capture system, where markers are positioned at strategic points, we manage to acquire the movement of the hand and establish its orientation using a minimum number of markers. An Inverse Kinematics solver was then employed to control the postures of the hand, subject to physiological constraints that restrict the allowed movements to a feasible and natural set.

[DOI] [paper] [video] [bibtex] [project page]

Continuous body emotion recognition system during theater performances

Simon Senecal, Louis Cuel, Andreas Aristidou, Nadia Magnenat-Thalmann

Comp. Animation & Virtual Worlds, 27(3-4): 311-320, 2016.

Proceedings of Computer Animation and Social Agents - CASA'16

We propose a system for continuous emotional behavior recognition expressed by people during communication based on their gesture and their whole body dynamical motion. The features used to classify the motion are inspired by the Laban Movement Analysis. Using a trained neural network and annotated data, our system is able to describe the motion behavior as trajectories on the Russell Circumplex Model diagram during theater performances over time.

[DOI] [paper] [bibtex]

Extending FABRIK with Model Constraints

Andreas Aristidou, Yiorgos Chrysanthou, Joan Lasenby

Comp. Animation & Virtual Worlds, 27(1): 35-57, 2016.

This paper addresses the problem of manipulating articulated figures in an interactive and intuitive fashion for the design and control of their posture using the FABRIK algorithm; the algorithm has been extended to support a variation of different joints and has been evaluated on a humanoid model.

[DOI] [paper] [video] [bibtex] [project page]

Folk Dance Evaluation Using Laban Movement Analysis

Andreas Aristidou, Efstathios Stavrakis, Panayiotis Charalambous, Yiorgos Chrysanthou, Stephania L. Himona

ACM Journal on Computing and Cultural Heritage, 8(4): 1-19, 2015.

Best paper award at EG GCH 2014.

We present a framework based on the principles of Laban Movement Analysis (LMA) that aims to identify style qualities in dance motions, and can be subsequently used for motion comparison and evaluation. We have designed and implemented a prototype virtual reality simulator for teaching folk dances in which users can preview dance segments performed by a 3D avatar and repeat them. The user’s movements are captured and compared to the folk dance template motions; then, intuitive feedback is provided to the user based on the LMA components.

[DOI] [paper] [video] [bibtex] [project page]

Emotion analysis and classification: Understanding the performers’ emotions using LMA entities

Andreas Aristidou, Panayiotis Charalambous, Yiorgos Chrysanthou

Computer Graphics Forum, 34(6): 262–276, 2015.

Presented at Eurographics 2016.

We proposed a variety of features that encode characteristics of motion, in terms of Laban Movement Analysis, for motion classification and indexing purposes. Our framework can be used to extract both the body and stylistic characteristics, taking into consideration not only the geometry of the pose but also the qualitative characteristics of the motion. This work provides some insights on how people express emotional states using their body, while the proposed features can be used as alternative or complement to the standard similarity, motion classification and synthesising methods.

[DOI] [paper] [video] [bibtex] [project page]

Cypriot Intangible Cultural Heritage: Digitizing Folk Dances

Andreas Aristidou, Efstathios Stavrakis, Yiorgos Chrysanthou

Cyprus Computer Society journal, Issue 25, pages 42-49, 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]

Real-time marker prediction and CoR estimation in optical motion capture

Andreas Aristidou, Joan Lasenby

The Visual Computer, 29 (1): 7-26, 2013.

An integrated framework is presented which predicts the occluded marker positions using a Variable Turn Model within an Unscented Kalman filter. Inferred information from neighbouring markers is used as observation states; these constraints are efficient, simple, and real-time implementable. An Inverse Kinematics solver is then applied ensuring that the bone lengths remain constant over time; the system can thereby maintain a continuous data-flow.

[DOI] [paper] [video] [bibtex] [project page]

Inverse Kinematics solutions using Conformal Geometric Algebra

Andreas Aristidou, Joan Lasenby

Guide to Geometric Algebra in Practice, L. Dorst and J. Lasenby (Eds), pages 47-62, Springer Verlag, 2011.

An iterative Inverse Kinematics solver is implemented using Conformal Geometric Algebra. We use a human hand as an example of implementation where a constrained version of the IK solver is employed for pose tracking. The hand is modelled using CGA, taking advantage of CGA’s compact and geometrically intuitive framework, that basic entities in CGA, such as spheres, lines, planes and circles, are simply represented by algebraic objects.

[DOI] [paper] [ppt] [bibtex] [project page]

FABRIK: a fast, iterative solver for the inverse kinematics problem

Andreas Aristidou, Joan Lasenby

Graphical Models, 73(5): 243-260, 2011

A novel heuristic method, called Forward And Backward Reaching Inverse Kinematics (FABRIK), is described that avoids the use of rotational angles or matrices, and instead finds each joint position via locating a point on a line. Thus, it converges in few iterations, has low computational cost and produces visually realistic poses. Constraints can easily be incorporated within FABRIK and multiple chains with multiple end effectors are also supported.

[DOI] [paper] [video] [bibtex] [project page]

Other Publications

Conference Proceedings

  • A Conformal Geometric Algebra framework for Mixed Reality and mobile display
    Margarita Papaefthimiou, George Papagiannakis, Andreas Aristidou, Marinos Ioannides
    In Proceedings of the 6th Conference on Applied Geometric Algebra in Computer Science and Engineering (AGACSE’15), Barcelona, Spain, July 2015.
    [paper] [bibtex]
  • LMA-Based Motion Retrieval for Folk Dance Cultural Heritage
    Andreas Aristidou, Efstathios Stavrakis, Yiorgos Chrysanthou
    In Proceedings of the 5th International Conference on Cultural Heritage (EuroMed’14), LNCS, volume 8740, pages 207-216, Limassol, Cyprus, November 3 – 8, 2014.
    [DOI] [paper] [bibtex]
  • Motion Analysis for Folk Dance Evaluation
    Andreas Aristidou, Efstathios Stavrakis, Yiorgos Chrysanthou
    In Proceedings of the 12th EUROGRAPHICS Workshop on Graphics and Cultural Heritage (GCH), pages 55-64, Darmstadt, Germany, October 5 – 8, 2014. [Best Paper Award]
    [DOI] [paper] [bibtex]
  • Feature extraction for human motion indexing of acted dance performances
    Andreas Aristidou, Yiorgos Chrysanthou
    In Proceedings of the 9th International Conference on Computer Graphics Theory and Applications (GRAPP’14), pages 277-287, Portugal, January 05-08, 2014.
    [DOI] [paper] [bibtex]
  • Motion indexing of different emotional states using LMA components
    Andreas Aristidou, Yiorgos Chrysanthou
    In SIGGRAPH Asia Technical Briefs (SA’13), ACM, New York, USA, 21:1-21:4, 2013.
    [DOI] [paper] [bibtex]
  • Emotion Recognition for Exergames using Laban Movement Analysis
    Haris Zacharatos, Christos Gatzoulis, Yiorgos Chrysanthou, Andreas Aristidou
    In Proceedings of ACM Motion in Games (MIG’13), Ireland, November 7-9, 2013.
    [DOI] [paper] [bibtex]
  • Digitization of Cypriot Folk Dances
    Efstathios Stavrakis, Andreas Aristidou, Maria Savva, Stephania Loizidou Himona, Yiorgos Chrysanthou
    In Proceedings of the 4th International Conference on Progress in Cultural Heritage Preservation (EuroMed’12), LNCS, Volume 7616, pages 404-413, 2012.
    [DOI] [paper] [bibtex]
  • Motion Capture with Constrained Inverse Kinematics for Real-Time Hand Tracking
    Andreas Aristidou, Joan Lasenby
    In IEEE Proceedings of the 4th International Symposium on Communications, Control and Signal Processing (ISCCSP’10), Limassol, Cyprus, May 3-5, 2010.
    [DOI] [paper] [bibtex]
  • Predicting Missing Markers to Drive Real-Time Centre of Rotation Estimation
    Andreas Aristidou, Jonathan Cameron, Joan Lasenby
    In Proceedings of the International Conference on Articulated Motion and Deformable Objects (AMDO'08), LNCS, Vol. 5098, pages 238-247, Mallorca, Spain, July 9-11, 2008.
    [DOI] [paper] [bibtex]
  • Real-Time Estimation of Missing Markers in Human Motion Capture
    Andreas Aristidou, Jonathan Cameron, Joan Lasenby
    In IEEE Proceedings of the International Conference on Bioinformatics and Biomedical Engineering (iCBBE'08), pages 1343-1346, Shanghai, China, May 16-18, 2008.
    [DOI] [paper] [bibtex]
  • Tracking Multiple Sports Players for Mobile Display
    Andreas Aristidou, Paul Pangalos, Hamid Aghvami
    In Proceeding of the International Conference on Image Processing, Computer Vision, and Pattern Recognition, IPCV'07, pages 53-59, Las Vegas, USA, June 25-28, 2007.
    [DOI] [paper] [bibtex]
  • Violent Content Classification using Audio Features
    Theodoros Giannakopoulos, Dimitrios Kosmopoulos, Andreas Aristidou, Sergios Theodoridis
    In Proceedings of the Hellenic Artificial Intelligence Conference SETN-06, LNCS, Volume 3955, pages 502-507, Heraklion, Crete, Greece, May 18-20, 2006.
    [DOI] [paper] [bibtex]

Final Thesis

  • Tracking and Modelling Motion for Biomechanical Analysis
    Andreas Aristidou
    A dissertation submitted to the University of Cambridge for the Degree of Doctor of Philosophy, Cambridge, October 2010.
    Supervisor: Dr Joan Lasenby, Examiners: Prof William J. Fitzgerald & Prof Adrian Hilton.
    [paper] [bibtex]
  • Reliable indexing and recognition of violent scenes using audio features
    Andreas Aristidou
    Annual journal of the Department of Informatics & Telecommunications, Best dissertations of the year, pages 127-136, Athens, Greece, 2006.
    Supervisor: Prof Sergios Theodoridis
    [paper] [bibtex]

Technical Reports

  • Marker Prediction and Skeletal Reconstruction in Motion Capture Technology
    Andreas Aristidou, Yiorgos Chrysanthou
    Technical Report (UCY-CS-TR-13-2), University of Cyprus, August 2013.
    [paper] [bibtex]
  • Inverse Kinematics: a review of existing techniques and introduction of a new fast iterative solver
    Andreas Aristidou, Joan Lasenby
    Technical Report (CUEDF-INFENG, TR-632), University of Cambridge, September 2009
    [paper] [bibtex]
  • Methods for Real-time Restoration and Estimation in Optical Motion Capture
    Andreas Aristidou, Joan Lasenby, Jonathan Cameron
    Technical Report (CUEDF-INFENG, TR-619), University of Cambridge, January 2009.
    [paper] [bibtex]

© 2017 Andreas Aristidou