Anastasios Yiannakides, Andreas Aristidou, Yiorgos Chrysanthou
Comp. Animation & Virtual Worlds, 30(3-4), 2019.
Proceedings of Computer Animation and Social Agents - CASA'19
In this paper, we present a method that reconstructs articulated human motion, taken from a monocular RGB camera. Our method fits 2D deep estimated poses of multiple characters, with the 2D multi-view joint projections of 3D motion data, to retrieve the 3D body pose of the tracked character. By taking into consideration the temporal consistency of motion, it generates natural and smooth animations, in real-time, without bone length violations.
Andreas Aristidou, Daniel Cohen-Or, Jessica K. Hodgins, Yiorgos Chrysanthou, Ariel Shamir
ACM Transaction on Graphics, 37(6), Article 187, 2018.
Proceedings of SIGGRAPH Asia 2018.
We introduce deep motion signatures, which are time-scale and temporal-order invariant, offering a succinct and descriptive representation of motion sequences. We divide motion sequences to short-term movements, and then characterize them based on the distribution of those movements. Motion signatures allow segmenting, retrieving, and synthesizing contextually similar motions.
Andreas Aristidou, Daniel Cohen-Or, Jessica K. Hodgins, Ariel Shamir
Computer Graphics Forum, 37(2): 297-309, 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.
Andreas Aristidou, Joan Lasenby, Yiorgos Chrysanthou, Ariel Shamir
Computer Graphics Forum, 37(6): 35-58, 2018.
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.
Andreas Aristidou, Efstathios Stavrakis, Margarita Papaefthimiou, George Papagiannakis, Yiorgos Chrysanthou
The Visual Computer, 34(12), 1725-1737, 2018.
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. Implemented in the context of Motion Graphs, it is used to eliminate potentially problematic transitions and synthesize style-coherent animation, without requiring prior labeling of the data.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
© 2017 Andreas Aristidou