Dr. George Papagiannakis

Dr. George Papagiannakis

Computer Scientist, co-founder & CEO, Professor, Researcher, Entrepreneur

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A list of all the posts and pages found on the site. For you robots out there is an XML version available for digesting as well.

Pages

Posts

Future Blog Post

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Blog Post number 4

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Blog Post number 2

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Blog Post number 1

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portfolio

publications

VHD++ Framework: Extendible Game Engine with Reusable Components, for VR/AR R&D featuring Advanced Virtual Character Simulation Technologies

Published in Computer Graphics International 2003, 2003

This paper presents the architecture of the VHD++ real-time development framework that after several years of intensive research, design, and development effort has been released and enters its validation phase. This paper discusses the key aspects involved in architectural structure, design and practical implementation of an efficient, flexible and extendible real-time software framework based on the modern 3D game-engine design principles. This framework supports researchers and application developers with rapid, component based development of VR/AR systems featuring advanced virtual character simulation technologies. The discussion covers motivation, main concepts, survey of related work, the main functional and design requirements, design principles and key architectural elements. It concludes with the initial validation results including overview of existing VHD++ based VR/AR virtual character simulation applications

Recommended citation: Ponder, M., Papagiannakis, G., Molet, T., Magnenat-Thalmann, N., Thalmann, D., VHD++ Framework: Extendible Game Engine with Reusable Components, for VR/AR R&D featuring Advanced Virtual Character Simulation Technologies, Proc. of Computer Graphics International03, pp. 96-104, IEEE Computer Society Press, Tokyo, July 2003 https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=71f106e688533a83e2b3eed62e264e06595f170c

A survey of mobile and wireless technologies for augmented reality systems

Published in COMPUTER ANIMATION AND VIRTUAL WORLDS, 2008

Recent advances in hardware and software for mobile computing have enabled a new breed of mobile augmented reality (AR) systems and applications. A new breed of computing called "augmented ubiquitous computing" has resulted from the convergence of wearable computing, wireless networking, and mobile AR interfaces.

Recommended citation: Papagiannakis, G., Singh, G., Magnenat-Thalmann, N., "A survey of mobile and wireless technologies for augmented reality systems", Journal of Computer Animation and Virtual Worlds, John Wiley and Sons Ltd, 19, 1, pp. 3-22, February 2008 http://papagiannakis.github.io/files/J6-2008-Papagiannakis.pdf

Geometric algebra rotors for skinned character animation blending

Published in ACM SIGGRAPH Asia 2013, 2013

The main goal and contribution of this work is to show that (automatically generated) computer implementations of geometric algebra (GA) can perform at a faster level compared to standard (dual) quaternion geometry implementations for real-time character animation blending. By this we mean that if some piece of geometry (e.g. Quaternions) is implemented through geometric algebra, the result is as efficient in terms of visual quality and even faster (in terms of computation time and memory usage) as the traditional quaternion and dual quaternion algebra implementation. This should be so even without taking into account certain algorithmic enhancements that geometric algebra may allow in selected applications. This work describes two implementation approaches for quaternion interpolation using Euclidean GA rotors for skinned character animation blending. It also lays the foundation so that GA can be employed for further calculations (skinning, rendering) under a unified geometry computation framework.

Recommended citation: George Papagiannakis. 2013. Geometric algebra rotors for skinned character animation blending. In SIGGRAPH Asia 2013 Technical Briefs (SA '13). Association for Computing Machinery, New York, NY, USA, Article 11, 1-6. https://doi.org/10.1145/2542355.2542369 https://dl.acm.org/doi/abs/10.1145/2542355.2542369

glGA: an OpenGL Geometric Application framework for a modern, shader-based computer graphics curriculum

Published in Eurographics 2014 - Education Papers , 2014

This paper presents the open-source glGA (Opengl Geometric Application) framework, a lightweight, shaderbased, comprehensive and easy to understand computer graphics (CG) teaching C++ system that is used for educational purposes, with emphasis on modern graphics and GPU application programming. This framework with the accompanying examples and assignments has been employed in the last three Semesters in two different courses at the Computer Science Department of the University of Crete, Greece. It encompasses four basic Examples and six Sample Assignments for computer graphics educational purposes that support all major desktop and mobile platforms, such as Windows, Linux, MacOSX and iOS using the same code base. We argue about the extensibility of this system, referring to an outstanding postgraduate project built on top of glGA for the creation of an Augmented Reality Environment, in which life-size, virtual characters exist in a marker-less real scene. Subsequently, we present the learning results of the adoption of this CG framework by both undergraduate and postgraduate university courses as far as the success rate and student grasp of major, modern, shader-based CG topics is concerned. Finally, we summarize the novel educative features that are implemented in glGA, in comparison with other systems, as a medium for improving the teaching of modern CG and GPU application programming

Recommended citation: Papagiannakis, G., Papanikolaou, P., Greassidou, E., and Trahanias, P., glGA: an OpenGL Geometric Application framework for a modern, shader-based computer graphics curriculum. Eurographics2014, Education Papers, Strasbourg, April 2014 https://diglib.eg.org/handle/10.2312/eged.20141026.009-016

A fast and robust pipeline for populating mobile AR scenes with gamified virtual characters

Published in ACM SIGGRAPH Asia 2015, 2015

In this work we present a complete methodology for robust authoring of AR virtual characters powered from a versatile character animation framework (Smartbody), using only mobile devices

Recommended citation: Papaefthymiou, M., Feng, A., Shapiro, A., Papagiannakis, G., "A fast and robust pipeline for populating mobile AR scenes with gamified virtual characters", ACM SIGGRAPH-ASIA 2015, Symposium On Mobile Graphics and Interactive Applications, Kobe, ACM Press, November 2015 http://papagiannakis.github.io/files/P22-2015-PapaefthymiouGP.pdf

Mixed Reality, Gamified Presence, and Storytelling for Virtual Museums

Published in Encyclopedia of Computer Graphics and Games. Springer, 2018

Mixed reality as display technology, gamification as motivational element, and storytelling as interaction metaphor while maintaining the feeling of presence are identified as key elements for defining the next generation of virtual museums

Recommended citation: Papagiannakis G., Geronikolakis, E., Pateraki, M., Lopez-Menchero, M.V., Tsioumas, M., Sylaiou, S., Liarokapis, F., Grammatikopoulou, A., Dimitropoulos, K., Grammalidis, N., Partarakis, N., Margetis, G., Drossis, G., Vassiliadi, M., Chalmers,A., Stephanidis, C., Magnenat-Thalmann, N., "Mixed Reality, Gamified Presence, and Storytelling for Virtual Museums", In: Lee N. (eds) Encyclopedia of Computer Graphics and Games. Springer, Cham, 2018 http://papagiannakis.github.io/files/C10-2018-Papagiannakis.pdf

MAGES 4.0: Accelerating the World’s Transition to VR Training and Democratizing the Authoring of the Medical Metaverse

Published in IEEE Comput. Graph. Appl. , 2023

In this work, we propose MAGES 4.0, a novel software development kit to accelerate the creation of collaborative medical training applications in virtual/augmented reality (VR/AR).

Recommended citation: Zikas, P., Protopsaltis, A., Lydatakis, N., Kentros, M., Geronikolakis, S., Kateros, S., Kamarianakis, M., Evangelou, G., Filippidis, A., Grigoriou, E., Angelis, D., Tamiolakis, M., Dodis, M., Kokiadis, G., Petropoulos, J., Pateraki, M., Papagiannakis, G., "MAGES 4.0: Accelerating the World's Transition to VR Training and Democratizing the Authoring of the Medical Metaverse", IEEE Comput. Graph. Appl. 43, 2, 43-56. DOI:https://doi.org/10.1109/mcg.2023.3242686, 2023 https://ieeexplore.ieee.org/document/10038619

Project Elements: A computational entity-component-system in a scene-graph pythonic framework, for a neural, geometric computer graphics curriculum

Published in Eurographics 2023 - Education Papers , 2023

We present the Elements project, a lightweight, open-source, computational science and computer graphics (CG) framework, tailored for educational needs, that offers, for the first time, the advantages of an Entity-Component-System (ECS) along with the rapid prototyping convenience of a Scenegraph-based pythonic framework. This novelty allows advances in the teaching of CG: from heterogeneous directed acyclic graphs and depth-first traversals, to animation, skinning, geometric algebra and shader-based components rendered via unique systems all the way to their representation as graph neural networks for 3D scientific visualization.

Recommended citation: Papagiannakis, G., Kamarianakis, M., Protopsaltis, A., Angelis, D., Zikas, P., "Project Elements: A computational entity-component-system in a scenegraph pythonic framework, for a neural, geometric computer graphics curriculum", in Eurographics 2023 - Education Papers (eds. Magana & Zara, A.), The Eurographics Association, doi:10.2312/eged.20231015, 2023 http://papagiannakis.github.io/files/P38-2023.pdf

A Computational Medical XR discipline

Published in arxiv.org, 2023

This paper is about Computational Medical XR(eXtended Reality) which brings together life sciences and neuroscience with mathematics, engineering, and computer science. It unifies computational science (scientific-neural computing) with intelligent extended reality and spatial computing for the medical field.

Recommended citation: Papagiannakis, George. “A computational medical XR discipline.” ArXiv abs/2108.04136v3 (2023): n. pag. https://arxiv.org/abs/2108.04136

Geometric Algebra Meets Large Language Models: Instruction-Based Transformations of Separate Meshes in 3D, Interactive and Controllable Scenes

Published in https://arxiv.org/abs/2408.02275, 2024

This paper introduces a novel integration of Large Language Models (LLMs) with Conformal Geometric Algebra (CGA) to revolutionize controllable 3D scene editing, particularly for object repositioning tasks, which traditionally requires intricate manual processes and specialized expertise. These conventional methods typically suffer from reliance on large training datasets or lack a formalized language for precise edits. Utilizing CGA as a robust formal language, our system, shenlong, precisely models spatial transformations necessary for accurate object repositioning. Leveraging the zero-shot learning capabilities of pre-trained LLMs, shenlong translates natural language instructions into CGA operations which are then applied to the scene, facilitating exact spatial transformations within 3D scenes without the need for specialized pre-training. Implemented in a realistic simulation environment, shenlong ensures compatibility with existing graphics pipelines. To accurately assess the impact of CGA, we benchmark against robust Euclidean Space baselines, evaluating both latency and accuracy. Comparative performance evaluations indicate that shenlong significantly reduces LLM response times by 16% and boosts success rates by 9.6% on average compared to the traditional methods. Notably, shenlong achieves a 100% perfect success rate in common practical queries, a benchmark where other systems fall short. These advancements underscore shenlong's potential to democratize 3D scene editing, enhancing accessibility and fostering innovation across sectors such as education, digital entertainment, and virtual reality.

Recommended citation: https://doi.org/10.48550/arXiv.2408.02275 https://doi.org/10.48550/arXiv.2408.02275

talks

teaching