George Papagiannakis

• B.Eng., M.Sc., Ph.D.,
• Professor at University of Crete

[This corrects the article DOI: 10.2196/54049.].

UNSTRUCTURED Patients undergoing surgery often experience stress and anxiety, which can increase complications and hinder recovery. Effective management of these psychological factors is key to improving outcomes. Preoperative anxiety is inversely correlated with the amount of information patients receive, but accessible, personalized support remai...

Background Patients undergoing surgery often experience stress and anxiety, which can increase complications and hinder recovery. Effective management of these psychological factors is key to improving outcomes. Preoperative anxiety is inversely correlated with the amount of information patients receive, but accessible, personalized support remains...

This work proposes a novel approach to transform any modern game engine pipeline, for optimized performance and enhanced user experiences in extended reality (XR) environments decoupling the physics engine from the game engine pipeline and using a client‐server architecture creates a scalable solution, efficiently serving multiple graphics clients...

In computer graphics (CG) education, the challenge of finding modern, versatile tools is significant, particularly when integrating both legacy and advanced technologies. Traditional frameworks, often reliant on solid, yet outdated APIs like OpenGL, limit the exploration of cutting-edge graphics techniques. To address this, we introduce pyGANDALF,...

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...

This work proposes a novel approach to transform any modern game engine pipeline, for optimized performance and enhanced user experiences in Extended Reality (XR) environments. Decoupling the physics engine from the game engine pipeline and using a client-server N-1 architecture creates a scalable solution, efficiently serving multiple graphics cli...

Physical exercise (PE) was proven crucial for cognitive health, for both demented and cognitively intact individuals. Simultaneous cognitive training may augment PE beneficial effects in demented patients. However, it is still debatable how PE and/or cognitive training reflect on mild cognitive impairment (MCI) and pathological factors related to A...

This paper introduces GA-Unity, the first Unity package specifically designed for seamless integration of Geometric Algebra (GA) into collaborative networked applications. Indeed, in such contexts, it has been demonstrated that using multivectors for interpolation between transmitted poses reduces runtime by 16% and bandwidth usage by an average of...

Contemporary progress in the field of robotics, marked by improved efficiency and stability, has paved the way for the global adoption of surgical robotic systems (SRS). While these systems enhance surgeons' skills by offering a more accurate and less invasive approach to operations, they come at a considerable cost. Moreover, SRS components often...

Low latency and high bandwidth heralded with 5G networks will allow transmission of large amounts of Mission-Critical data over a short time period. 5G hence unlocks several capabilities for novel Public Protection and Disaster Relief (PPDR) applications, developed to support first responders in making faster and more accurate decisions during time...

Background Virtual reality (VR) technology has become increasingly used for assessment and intervention in the neuroscience field. Objective We aimed to investigate the effects of a VR Training System, named VRADA (VR Exercise App for Dementia and Alzheimer’s Patients), on the cognitive functioning of older people with mild cognitive impairment (M...

Purpose Virtual reality (VR) training effectiveness in improving hip arthroplasty surgical skills requires further evaluation. We hypothesised VR training could improve accuracy and the time taken by medical students compared to a control group with only video teaching. Methods This single-centre randomized controlled clinical trial collected data...

BACKGROUND Patients undergoing surgery often experience stress and anxiety, which can increase complications and hinder recovery. Effective management of these psychological factors is key to improving outcomes. Preoperative anxiety is inversely correlated with the amount of information patients receive, but accessible, personalized support remains...

Background Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a potentially life-saving procedure for bleeding trauma patients. Being a rare and complex procedure performed in extreme situations, repetitive training of REBOA teams is critical. Evidence-based guidelines on how to train REBOA are missing, although simulation-based t...

This survey introduces 101 new publications on applications of Clifford's geometric algebras (GAs) newly published during 2022 (until mid‐January 2023). The selection of papers is based on a comprehensive search with Dimensions.ai, followed by detailed screening and clustering. Readers will learn about the use of GA for mathematics, computation, su...

This work presents the introduction of UniSG^GA, a novel integrated scenegraph structure, that to incorporates behavior and geometry data on a 3D scene. It is specifically designed to seamlessly integrate Graph Neural Networks (GNNs) and address the challenges associated with transforming a 3D scenegraph (3D-SG) during generative tasks. To effectiv...

Virtual reality (VR) simulations as an assessment tool represent a much-needed effort to move beyond the shortcomings of today's forms-based measures. Within VR, we assess for competency and problem-solving skills versus the content memorization typically supported by multiple-choice assessments. This chapter reviews the development process for the...

Virtual reality simulations represent a much-needed effort to move beyond the shortcomings of traditional form-based assessments. Within VR, we assess competency and problem-solving skills versus the content memorization typically supported by conventional measures. This chapter explores an innovative VR simulation recently deployed at Western Gove...

We envision a no-code solution that generates new nodes, edges and features reflecting the creation of 3D models, scenes and even new behavioral steps through GNNs. To this end, we propose a novel Universal Scenegraph (UniSG), that unifies entity-component-systems, 3D and learning scenegraphs with GNNs to empower generative AI, and facilitate the c...

In this work, we propose MAGES 4.0, a novel Software Development Kit (SDK) to accelerate the creation of collaborative medical training applications in VR/AR. Our solution is essentially a low-code metaverse authoring platform for developers to rapidly prototype high-fidelity and high-complexity medical simulations. MAGES breaks the authoring bound...

Surgeons should play a central role in disaster planning and management due to the overwhelming number of bodily injuries that are typically involved during most forms of disaster. In fact, various types of surgical procedures are performed by emergency medical teams after sudden-onset disasters, such as soft tissue wounds, orthopaedic traumas, abd...

We present the Elements project, a computational science and computer graphics (CG) framework, 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 acycli...

As shared, collaborative, networked, virtual environments become increasingly popular, various challenges arise regarding the efficient transmission of model and scene transformation data over the network. As user immersion and real-time interactions heavily depend on VR stream synchronization, transmitting the entire data set does not seem a suita...

This manuscript details a comprehensive protocol for a study that will provide valuable information about the intervention program, such as the measurement of comparative intervention effects on stress; anxiety and pain management; and usability by patients, caregivers, and health care professionals. This will contribute to the evidence planning pr...

Augmented reality (AR) and mixed reality (MR) applications have gained momentum the past couple of years among researchers. Even though many approaches have addressed the challenges and opportunities of evaluating such applications and some have even used these technologies as evaluation methods, only a few attempts have been made in creating tools...

In this work, we propose MAGES 4.0, a novel Software Development Kit (SDK) to accelerate the creation of collaborative medical training scenarios in VR/AR. Our solution offers a versatile authoring platform for developers to create medical simulations in a future-proof, low-code environment. MAGES breaks the boundaries between realities since stude...

We present an algorithm that allows a user within a virtual environment to perform real-time unconstrained cuts or consecutive tears, i.e., progressive, continuous fractures on a deformable rigged and soft-body mesh model in high-performance 10ms. In order to recreate realistic results for different physically-principled materials such as sponges,...

Purpose According to World Health Organization, our planet will need more than 40 million new doctors, nurses, frontline healthcare workers, and other healthcare professionals by the year 2030, which is double the current medical workforce (1). The existing training model (a master teaching a limited number of apprentices over the course of several...

We introduce a novel method that describes the functionality and characteristics of an efficient VR recorder with replay capabilities, implemented in a modern game engine, publicly available for free.

We present a Convolutional Neural Network (CNN) suitable to assess unconstrained surgical cuttings, trained on a dataset created with a data augmentation technique.

We present a novel integration of a real-time continuous tearing algorithm for 3D meshes in VR, suitable for devices of low CPU/GPU specifications, along with a suitable particle decomposition that allows soft-body deformations on both the original and the torn model.

Visualizing human motion is a topic that has gained increasing attention in the domain of cultural heritage, due to the need for capturing intangible dimensions, existing for example in theatrical performances, dances, and crafts. In this respect, virtual humans are typically employed to re-enact human motion, executing movements reproduced through...

BACKGROUND Stress and anxiety are psychophysiological responses commonly experienced by patients during a perioperative process that can increase pre- and post-surgical complications to a comprehensive and positive recovery. Preventing and intervening stress and anxiety can help patients achieve positive outcomes on health and wellbeing. Similarly,...

Background Stress and anxiety are psychophysiological responses commonly experienced by patients during the perioperative process that can increase presurgical and postsurgical complications to a comprehensive and positive recovery. Preventing and intervening in stress and anxiety can help patients achieve positive health and well-being outcomes. S...

As shared, collaborative, networked, virtual environments become increasingly popular, various challenges arise regarding the efficient transmission of model and scene transformation data over the network. As user immersion and real-time interactions heavily depend on VR stream synchronization, transmitting the entire data sat does not seem a suita...

In this work, a novel computational approach for the dynamic adaptation of User Interfaces (UIs) is proposed, which aims at enhancing the Situational Awareness (SA) of users by leveraging the current context and providing the most useful information, in an optimal and efficient manner. By combining Ontology modeling and reasoning with Combinatorial...

In recent years, the emergence of XR (eXtended Reality) applications, including Holography, Augmented, Virtual and Mixed Reality, has resulted in the creation of rather demanding requirements for Quality of Experience (QoE) and Quality of Service (QoS). In order to cope with requirements such as ultra-low latency and increased bandwidth, it is of p...

In this work, we propose two algorithms that can be applied in the context of a networked virtual environment to efficiently handle the interpolation of displacement data for hand-based VR HMDs. Our algorithms, based on the use of dual-quaternions and multivectors respectively, impact the network consumption rate and are highly effective in scenari...

In this work, we present an integrated geometric framework: "deep- cut" that enables for the first time a user to geometrically and algorithmically cut, tear and drill the surface of a skinned model without prior constraints, layered on top of a custom soft body mesh deformation algorithm. Both layered algorithms in this frame- work yield real-time...

Computational Medical Extended Reality (CMXR), brings together life sciences and neuroscience with mathematics, engineering and computer science. It unifies computational science (scientific computing) with intelligent extended reality and spatial computing for the medical field. It significantly differs from previous "Clinical XR" or "Medical XR"...

In this work, we propose two algorithms that can be applied in the context of a networked virtual environment to efficiently handle the interpolation of displacement data for hand-based VR HMDs. Our algorithms, based on the use of dual-quaternions and multivectors respectively, impact the network consumption rate and are highly effective in scenari...

Conformal geometric algebra (CGA) is a framework that allows the representation of objects, such as points, planes and spheres, and deformations, such as translations, rotations and dilations as uniform vectors, called multivectors. In this work, we demonstrate the merits of multivector usage with a novel, integrated rigged character simulation fra...

The primary mission of cultural institutions, including heritage sites and museums, is to perform and perpetuate Cultural Heritage (CH) by ideally transforming audiences into stewards of that heritage. In recent years, these institutions have increasingly turned to Mixed Reality (MR) technologies to expand and democratize public access to Cultural...

While the body of research focusing on Intelligent Environments (IEs) programming by adults is steadily growing, informed insights about children as programmers of such environments are limited. Previous work already established that young children can learn programming basics. Yet, there is still a need to investigate whether this capability can b...

While the body of research focusing on Intelligent Environments (IEs) programming by adults is steadily growing, informed insights about children as programmers of such environments are limited. Previous work already established that young children can learn programming basics. Yet, there is still a need to investigate whether this capability can b...

Visualization techniques for the usage of tools, handicrafts, and assembly operations are employed for demonstrating processes (e.g., assembly instructions). Until today, most commonly used techniques include written information, sketches in manuals, video instructions, etc. The evolution of technology nowadays has generated mature methods for tran...

Background: Although the proper use of hygiene and personal protective equipment (PPE) is paramount for preventing the spread of diseases such as COVID-19, health care personnel have been shown to use incorrect techniques for donning/doffing of PPE and hand hygiene, leading to a large number of infections among health professionals. Education and...

BACKGROUND Although the proper use of hygiene and personal protective equipment (PPE) is paramount for preventing the spread of diseases such as COVID-19, health care personnel have been shown to use incorrect techniques for donning/doffing of PPE and hand hygiene, leading to a large number of infections among health professionals. Education and tr...

Background Therapeutic virtual reality (VR) has emerged as an effective treatment modality for cognitive and physical training in people with mild cognitive impairment (MCI). However, to replace existing nonpharmaceutical treatment training protocols, VR platforms need significant improvement if they are to appeal to older people with symptoms of c...

Conformal Geometric Algebra (CGA) is a framework that allows the representation of objects, such as points, planes and spheres, and deformations, such as translations, rotations and dilations as uniform vectors, called multivectors. In this work, we demonstrate the merits of multivector usage with a novel, integrated rigged character simulation fra...

Applications of the Extended Reality (XR) spectrum, a superset of Mixed, Augmented and Virtual Reality, are gaining prominence and can be employed in a variety of areas, such as virtual museums. Examples can be found in the areas of education, cultural heritage, health/treatment, entertainment, marketing, and more. The majority of computer graphics...

This book constitutes the refereed proceedings of the 38th Computer Graphics International Conference, CGI 2021, held virtually in September 2021. The 44 full papers presented together with 9 short papers were carefully reviewed and selected from 131 submissions. The papers are organized in the following topics: computer animation; computer vision;...

Culture is a field that is currently entering a revolutionary phase, no longer being a privilege for the few, but expanding to new audiences who are urged to not only passively consume cultural heritage content, but actually participate and assimilate it on their own. In this context, museums have already embraced new technologies as part of their...

This paper explores a new approach to a teacher’s workstation in the context of the intelligent classroom of the 21st century. Nowadays, the term “intelligent” is not only associated with efforts to incorporate smart/mobile devices into the learning experience (distance learning, educational games/apps, etc.), but also to equip the physical environ...

In this work, we present a novel, integrated rigged character simulation framework in Conformal Geometric Algebra (CGA) that supports, for the first time, real-time cuts and tears, before and/or after the animation, while maintaining deformation topology. The purpose of using CGA is to lift several restrictions posed by current state-of-the-art cha...

Virtual reality (VR) has re-emerged as a low-cost, highly accessible consumer product, and training on simulators is rapidly becoming standard in many industrial sectors. However, the available systems are either focusing on gaming context, featuring limited capabilities or they support only content creation of virtual environments without any rapi...

BACKGROUND Therapeutic virtual reality (VR) has emerged as an effective treatment modality for cognitive and physical training in people with mild cognitive impairment (MCI). However, to replace existing nonpharmaceutical treatment training protocols, VR platforms need significant improvement if they are to appeal to older people with symptoms of c...

Background: Patients undergoing elective surgery often face symptoms of anxiety and stress. Healthcare systems have limited time and resources to provide individualized stress relief interventions. Research has shown that stress relief interventions and educational resources can improve health outcomes and speed recovery. Objectives: Digital health...

A basic understanding of problem-solving and computational thinking is undoubtedly a benefit for all ages. At the same time, the proliferation of Intelligent Environments has raised the need for configuring their behaviors to address their users’ needs. This configuration can take the form of programming, and coupled with advances in Augmented Real...

In this work, we present a novel, integrated rigged character simulation framework in Conformal Geometric Algebra (CGA) that supports, for the first time, real-time cuts and tears, before and/or after the animation, while maintaining deformation topology. The purpose of using CGA is to lift several restrictions posed by current state-of-the-art cha...

In this work, we present MAGES 3.0, a novel Virtual Reality (VR)-based authoring SDK platform for accelerated surgical training and assessment. The MAGES Software Development Kit (SDK) allows code-free prototyping of any VR psychomotor simulation of medical operations by medical professionals, who urgently need a tool to solve the issue of outdated...

In this work, a new and innovative way of spatial computing that appeared recently in the bibliography called True Augmented Reality (AR), is employed in cultural heritage preservation. This innovation could be adapted by the Virtual Museums of the future to enhance the quality of experience. It emphasises, the fact that a visitor will not be able...

Despite the cultural, societal, economic and traditional significance and value of Heritage Crafts and Intangible Cultural Heritage, efforts towards their digital representation and presentation, and subsequently their preservation, are scattered. To that end, this paper proposes an approach for their visualization in Virtual Environments, within w...

This book constitutes the refereed proceedings of the 37th Computer Graphics International Conference, CGI 2020, held in Geneva, Switzerland, in October 2020. The conference was held virtually. The 43 full papers presented together with 3 short papers were carefully reviewed and selected from 189 submissions. The papers address topics such as: virt...

This chapter will extend its preliminary scope by examining how literary transportation further amplifies presence and affects user response vis-\'a-vis virtual heritage by focusing on embodiment and aesthetic experience. To do so, it will draw on recent findings emerging from the fields of applied psychology, neuroaesthetics and cognitive literary...

In this work, a new and innovative way of cultural heritage preservation is dis-cussed. It is called "True Augmented Reality (AR)". True AR is defined as a modi-fication of the user's perception of their surroundings that cannot be detected by the user. This innovation could be adapted by the Virtual Museums of the future, in order to enhance the m...

Virtual reality (VR) has re-emerged as a low-cost, highly accessible consumer product, and training on simulators is rapidly becoming standard in many industrial sectors. Combined with the continued advancements in VR technology, the interest in platforms that generate immersive experiences has increased. However, the available systems are either f...

With the proliferation of Intelligent Environments, the need for configuring their behaviors to address their users’ needs emerges. In combination with the current advances in Augmented and Virtual Reality and Conversational Agents, new opportunities arise for systems which allow people to program their environment. Whereas today this requires prog...

Augmented, Virtual, and Mixed Reality have successfully transitioned from the laboratory environment to becoming mainstream technologies available to almost everyone, mainly due to important advancements in terms of hardware. These technologies, along with recent advancements in Artificial Intelligence, have the potential to deliver compelling expe...

Background: No study has yet assessed the efficacy of virtual reality (VR) simulation for teaching orthopedic surgery residents. In this blinded, randomized, and controlled trial, we asked if the use of VR simulation improved postgraduate year (PGY)-1 orthopedic residents' performance in cadaver total hip arthroplasty and if the use of VR simulati...

Anxiety and stress are very common symptoms of patients facing a forthcoming surgery. However, limited time and resources within healthcare systems make the provision of stress relief interventions difficult to provide. Research has shown that provision of preoperative stress relief and educational resources can improve health outcomes and speed re...

Anxiety and stress are very common symptoms of patients facing a forthcoming surgery. However, limited time and resources within healthcare systems make the provision of stress relief interventions difficult to provide. Research has shown that provision of preoperative stress relief and educational resources can improve health outcomes and speed re...

In this work, we propose a novel VR s/w system aiming to disrupt the healthcare training industry with the first Psychomotor Virtual Reality (VR) Surgical Training solution. Our system generates a fail-safe, realistic environment for surgeons to master and extend their skills in an affordable and portable solution. We deliver an educational tool fo...

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...