Work experience

  • image
    Feb 2021 today

    XR Developer & Researcher

    HITlab, HOWEST University, Belgium

  • image
    Dec 2019 today

    XR Technical Specialist

    self-employed (freelancer), Belgium

  • image
    Jun 2014 Dec 2019

    Researcher

    Vrije Univeristeit Brussel, Belgium

  • image
    Nov 2008 Apr 2014

    Web designer & IT Technician

    Freelancer (part-time)

  • image
    Dec 2006 Apr 2014

    Mathematics and physics tutor

    Freelancer (part-time)

  • image
    Apr 2008 May 2008

    Intern in electronic systems

    Makedonia Airport (SKG) in Thessaloniki

Education

  • image
    Ph.D. 2019

    Ph.D. in Engineering Sciences

    Vrije Univeristeit Brussel, Belgium

  • image
    MSc 2012

    Master of Science in Electronic Technology of Telecommunications

    Aristotle University of Thessaloniki, Greece

  • image
    BSc 2009

    Bachelor of Science in Physics

    Aristotle University of Thessaloniki, Greece

Languages

  • English
  • Greek
  • French
  • Dutch

Awards, Achievements and Certifications

  • Aug 2020
    Virtual Reality App Development Professional Certificate (UC San Diego)
    image
    This professional certificate is about contemporary VR technology and VR devices, how VR technology works, and how to write software for VR experiences and games. It includes effective 3D interaction techniques to use for VR applications, how to write such applications in WebVR and Unity3D, and what features make a VR application successful. The courses are:
    • Computer Graphics
    • How Virtual Reality Works
    • Creating Virtual Reality Apps
  • Jun 2017
    Certificaat van opleiding Nederlands richtraad 2 (CVO)
    image
    Knowledge of the Dutch language at B1 level - independent user.
  • Apr 2016
    SPIE best student paper award
    image
    "Speckle noise reduction for computer generated holograms of objects with diffuse surfaces"(Oral presentation)
    Best student paper award for the "Optics, Photonics and Digital Technologies for Imaging Applications" conference at SPIE Photonics Europe, April 2016.
  • Jun 2017
    HoloVizio 722RC operation and first line maintenance (Holografika)
    image
    Training on the operation and maintenance of the HoloVizio 722RC light-field dsplay by Holografika.
  • Apr 2014
    Cisco Certified Network Associate (CCNA, CISCO)
    image
    The CCNA certification validates skills and knowledge in network fundamentals, network access, IP connectivity, IP services, security fundamentals, and automation and programmability.
  • Jun 2013
    Diplôme d’études en Langue Française (DELF, CIEP)
    image
    Knowledge of the French language at B2 level - independent user.
  • Sep 2008
    ECDL Core Certificate (ECDL Foundation)
    image
    The 7 ECDL Core modules are: Concepts of Information Technology (IT), Using the Computer and Managing Files, Word Processing, Spreadsheets, Using Databases, Presentation, Information and Communication
  • Mar 2003
    Certificate of Proficiency in English (Univ. of Cambridge)
    image
    Knowledge of the English language at C2 level - proficient user.

VR Projects

  • image

    Interior Decorator

    App for Oculus Quest

    VR application that lets you decorate a predefined appartment. Tested on Oculus Quest.

  • image

    360o Image Viewer

    Equirectangular image viewer

    Basic application to render preselected equirectangular images in 360 degrees, with the added feature of loading your own equirectangular image.

Games

  • image

    Pandamic Runner

    3D endless runner game

    A 3D game developed Game developed during The Panda-mic Game Jam, 1-3 May 2020, hosted by Game Developers Assocation of Greece.

  • image

    Spaceship shooter

    2D game

    Shoot the enemy spaceships to survive!
    Developed while following the Udemy course "The Ultimate Guide to Game Development with Unity 2019". Most Assets are also from the course material.

  • image

    Fishing breakout

    2D game (breakout)

    Simple game with a fishing theme and 50 levels.

Animation

  • image

    Walk in nature

    Short animation

    Short landscape animated movie, made with Cinemachine, Timeline and Animator in Unity.

  • image

    Greek flag

    Short animation with the Greek national anthem

    Short animation made for the National Day for the declaration of Greek Revolution 21/10/1981. Early work to study the cloth texture, wind and adding audio clips.

Other Projects

  • image

    Driving simulation

    Research project

    The idea of the project was to capture photos of drivers using a smartphone wihile driving with traffic cameras.

Filter by type:

Sort by year:

Novel assessment tool for unilateral spatial neglect using virtual reality and eye-tracking

Lode Sabbe, Athanasia Symeonidou, Jelle Demanet, Siska Vandemaele
Conference Papers World Federation of Occupational Therapists (WFOT) Congress 2022, 28-31 Aug 2022

[Congress without proceedings]

Introduction: Unilateral spatial neglect (USN) is characterized by inattention to or inaction in the side of space opposite a brain lesion and affects 23-46% of stroke survivors. The effect of USN is often multimodal and requires skilled clinical staff to diagnose and treat. Currently, USN is assessed through paper-and-pencil tests that lack ecological validity and ignore the effects on activities of daily life. Current mobile head-mounted displays (HMD) in combination with eye tracking have become promising in evaluation and training.

Objective: The aim is to develop a novel immersive occupational therapy (OT) assessment tool for patients with USN. This tool has to be mobile and low cost in order to have a broad range of assessment possibilities in any service.

Method: Through an iterative process of software developers with occupational therapists and patients, an accurate and ecologically valid virtual reality (VR) system employable for assessment and training, will be created.

Results: A first version of a novel tool for assessment and training USN in VR is developed. The first accomplishment is a known analytical test in VR, the star cancellation task (VR Star). Eye tracking was added in order to gather extra biometric data and insights. Expected is that VR Star will provide multimodal, uniform and more objective data and become more motivating, sensitive and user-centered than existing tools.

Conclusion: A first USN assessment tool in VR, the VR Star, was created in spring 2021. In further development of the tool, tests on activity and participation levels are added. Further research will assess both feasibility and validity.

Smart immersive occupational performance assessment tool

Athanasia Symeonidou, Sam Van de Walle, Siska Vandemaele, Lode Sabbe, Jelle Demanet
Conference Papers VR4Rehab Congress 2022, 23-24 Jun 2022

[Congress without proceedings]

Introduction: Several assessment tools are used in occupational therapy; however, it is not always straightforward to have objective evaluation metrics between different occupational therapists and testing setups, which complicates the comparison of the patient’s performance before and after treatment, and also the comparison of the performances of the patients. The aim is to develop a novel immersive occupational therapy (OT) assessment tool for patients with various conditions. This tool must be portable, low cost and user friendly, so that both occupational therapists and patients can use it effortlessly in specialized services, private practices and at home.

Methods: A multidisciplinary team of occupational therapists, developers and psychologists is formed, so that the application is exact, user-friendly and valid from all perspectives. Through an iterative process of development and feedback collection from occupational therapy professionals and patients, a VR application for assessment and training, is created.

Results and discussion: For the first version of the application, on the focus is on patients with Unilateral Spatial Neglect (USN), since it is a common condition and virtual reality (VR) can provide immense added value with data analytics. The application consists of three tasks, namely the star cancellation task, the tray task, and a road-crossing task, targeting analytical, daily life and participation activities, respectively. Expected is that VR Star will provide with multimodal, uniform and more objective data and become more motivating, sensitive, and user-centered than existing tools. It is supported by a companion app that provides the OTs with analytics on the performance of the patients in real time and can be used to follow up their progress after each session.

Conclusions: A VR assessment tool is developed to support occupational therapists. In further development of the tool, more assessment tests will be added, and further research will confirm clinically the added value of the application in daily OT practice.

Work-in-Progress—Stress and Flow Assessment during a Virtual Reality Fire Extinguishing Training

Charlotte Larmuseau, Athanasia Symeonidou, Laetitia De Leersnijder, Jelle Demanet
Conference Papers 2022 8th International Conference of the Immersive Learning Research Network (iLRN), 30 May - 04 June 2022

Firefighters must be trained to deal with stress during firefighting and applying procedures. Aiming to alleviate the limitations in practice opportunities, a virtual reality (VR) application for training on fire extinguishing was developed, allowing for practice in a safe learning environment, while remaining aligned with the real-life training and the corresponding procedures. This work-in-progress paper investigates whether recruits experience stress and flow during the training by means of self-reported and physiological data. The physiological data measured (heart and respiration rate) significantly increased during the VR training, thus confirming arousal. The participants reported experiencing flow but not stress during the training.

Efficient algorithms for high-quality computer-generated holography

Athanasia Symeonidou
Jury members: Peter Schelkens (Promotor), Adrian Munteanu (Promotor), Gerd Vandersteen, (VUB), Rik Pintelon (VUB), Heidi Ottevaere (VUB), Aleksandra Pizurica (UGent), Tomasz Kozacki (Warsaw University of Technology), Patrick Gioia (b-com)
Doctoral Thesis Vrije Universiteit Brussel | November, 2019 | ISBN: 9789090325439

In recent years, three-dimensional display technology has seen huge advancements, targeting a more immersive 3D experience for a plethora of applications such as medical imaging, education, CAD, entertainment and more. However, the holy grail of three-dimensional imaging remains holography, since it is the most complete representation of a 3D scene. This is due to the fact that a hologram is a recording of both the intensity and the phase of a light wavefront representing the scene, providing us with all the necessary depth cues for full parallax three-dimensional visualization. Several disadvantages of digital holography, such as the need for optical recording and reconstruction setups and the optical aberrations can be overcome by computer-generated holography, which enables the calculation of the holographic pattern of synthetic scenes as well.

However, high-quality digital holograms raise limitations and challenges, regarding the signal processing, storage and display of holographic data. In particular, the computational complexity to calculate high resolution holograms cannot be handled by current hardware, while the contemporary holographic displays are limited, not allowing for large scale digital holograms to be displayed at a large resolution.

This thesis consists of several solutions to alleviate the aforementioned challenges. First, we present a novel algorithm for efficient generation of high-quality holograms of 3D scenes based on point cloud data. This computer-generated holography algorithm not only enables the generation of high resolution colour holograms in a fast manner, but also integrates occlusion handling and shading techniques for realistic 3D visualizations. Additionally, enabled by the above algorithm, several holographic datasets have been made publicly available, consisting of holographic data of various scenes, types and physical properties. Moreover, employing light field displays to overcome the need of an optical lab or a holographic display is proposed, by introducing a framework for rendering computer-generated and analog holograms on such displays. This framework can be accompanied by the speckle noise reduction techniques proposed, to tackle the speckle noise, which is an inherent property of holography. Last but not least, a method for the efficient generation of holographic videos is proposed, which is based on a motion compensation scheme. In this context, rigid motions of an object and their effect on the wavefield of the hologram are investigated to understand the limitations set by.

Suitability analysis of holographic vs light field and 2D displays for subjective quality assessment of Fourier holograms

Ayyoub Ahar, Maksymilian Chlipala, Tobias Birnbaum, Weronika Zaperty, Athanasia Symeonidou, Tomasz Kozacki, Malgorzata Kujawinska and Peter Schelkens
Journal PaperOptics Express. 28, 24, p. 37069-37091 23 p., 24, 20 November 2020

Measuring the impact of compression on the reconstruction quality of holograms remains a challenge. A public subjectively-annotated holographic data set that allows for testing the performance of compression techniques and quality metrics is presented, in addition to a subjective visual quality assessment methodology. Moreover, the performance of the quality assessment procedures is compared for holographic, regular 2D and light field displays. For these experiments, a double-stimulus, multi-perspective, multi-depth testing methodology was designed and implemented. Analysis of the quality scores indicated that in the absence of a suitable holographic display and under the presented test conditions, non-holographic displays can be deployed to display numerically reconstructed holograms for visual quality assessment tasks.

Object-based digital hologram segmentation and motion compensation

Tobias Birnbaum, David Blinder, Raees Kizhakkumkara Muhamad, Colas Schretter, Athanasia Symeonidou and Peter Schelkens
Journal PaperOptics Express. 28, 8, p. 11861-11882 22 p., 7 April 2020

Digital video holography faces two main problems: 1) computer-generation of holograms is computationally very costly, even more when dynamic content is considered; 2) the transmission of many high-resolution holograms requires large bandwidths. Motion compensation algorithms leverage temporal redundancies and can be used to address both issues by predicting future frames from preceding ones. Unfortunately, existing holographic motion compensation methods can only model uniform motions of entire 3D scenes. We address this limitation by proposing both a segmentation scheme for multi-object holograms based on Gabor masks and derive a Gabor mask-based multi-object motion compensation (GMMC) method for the compensation of independently moving objects within a single hologram. The utilized Gabor masks are defined in 4D space-frequency domain (also known as time-frequency domain or optical phase-space). GMMC can segment holograms containing an arbitrary number of mutually occluding objects by means of a coarse triangulation of the scene as side information. We demonstrate high segmentation quality (down to ≤ 0.01% normalized mean-squared error) with Gabor masks for scenes with spatial occlusions. The support of holographic motion compensation for arbitrary multi-object scenes can enable faster generation or improved video compression rates for dynamic digital holography.

Efficient holographic video generation based on rotational transformation of wavefields

Athanasia Symeonidou, Raees Kizhakkumkara Muhamad, Tobias Birnbaum, Peter Schelkens
Journal PaperOptics Express. 27, 26, p. 37383-37399 17 p. 23 December 2019

High-quality holographic video generation requires both high computational resources and time; therefore, algorithms that can generate holographic videos efficiently will be soon in demand for dynamic holographic 3D displays. In this work, we present two algorithms that use a motion compensation scheme – based on the rotational transformation of wavefields [Appl. Opt. 47, D110 (2008)], to generate efficiently holographic frames. The effects of motions to the wavefield are analyzed, while video generation examples are provided to support our theory. We report that with the proposed motion compensation scheme combined with the Phong multiple wavefront recording plane CGH method, a 10 times acceleration was achieved with regard to the ray tracing method, with a trade-off of energy loss of 10%. This speedup can be further improved by parallelization of the computations.

Exact global motion compensation for holographic video compression

Raees Kizhakkumkara Muhamad, David Blinder, Athanasia Symeonidou, Tobias Birnbaum, Osamu Watanabe, Colas Schretter, Peter Schelkens
Journal PaperApplied Optics (Feature: Digital Holography and 3-D Imaging 2019), Vol. 58 No. 34, December 2019

Holographic video requires impractical bitrates for storage and transmission without data compression. We introduce an end-to-end compression pipeline for compressing holographic sequences with known ground truth motion. The compression strategy employs a motion compensation algorithm based on the rotational transformation of angular spectrum. Residuals arising from the compensation step are represented using short-time Fourier transforms and quantized with uniform mid-rise quantizers whose bit depth is determined by a Lagrangian rate-distortion optimization criterion where the distortion metric is the mean squared error. Experiments uses computer generated holographic videos and we report Bjøntegaard delta peak signal to noise ratio gains of around 20 dB when compared to traditional image/video codecs.

Signal processing challenges for digital holographic video display systems

David Blinder, Ayyoub Ahar, Stijn Bettens, Tobias Birnbaum, Athanasia Symeonidou,Heidi Ottevaere, Colas Schretter, Peter Schelkens
Journal PaperSignal Processing: Image Communication, Vol. 70, Pages 114-130, February 2019

Holography is considered to be the ultimate display technology since it can account for all human visual cues such as stereopsis and eye focusing. Aside from hardware constraints for building holographic displays, there are still many research challenges regarding holographic signal processing that need to be tackled. In this overview, we delineate the steps needed to realize an end-to-end chain from digital content acquisition to display, involving the efficient generation, representation, coding and quality assessment of digital holograms. We discuss the current state-of-the-art and what hurdles remain to be taken to pave the way towards realistic visualization of dynamic holographic content.

Exact Compensation of Rotational Motion for Holographic Video Compression

Raees Kizhakkumkara Muhamad, Athanasia Symeonidou,David Blinder, Tobias Birnbaum, Colas Schretter, Peter Schelkens
Conference Papers Digital Holography and Three-Dimensional Imaging 2019, 19-23 May 2019

Holographic video imposes impractical bitrates for storage and communication without compression. We introduce exact motion compensation in a codec using rotational transformation of angular spectrum and obtain SNR improvements of 20 dB over HEVC.

Colour computer-generated holography for point clouds utilizing the Phong illumination model

Athanasia Symeonidou, David Blinder, Peter Schelkens
Journal Paper Optics Express, Vol. 26, Issue 8, pp. 10282-10298, April 2018

We propose a novel fast method for full parallax computer-generated holograms with occlusion processing, suitable for volumetric data such as point clouds. A novel light wave propagation strategy relying on the sequential use of the wavefront recording plane method is proposed, which employs look-up tables in order to reduce the computational complexity in the calculation of the fields. Also, a novel technique for occlusion culling with little additional computation cost is introduced. Additionally, the method adheres a Gaussian distribution to the individual points in order to improve visual quality. Performance tests show that for a full-parallax high-definition CGH a speedup factor of more than 2,500 compared to the ray-tracing method can be achieved without hardware acceleration.

Occlusion culling techniques for layer-based computer-generated holography

Athanasia Symeonidou and Peter Schelkens
Conference Papers Digital Holography and Three-Dimensional Imaging 2018, 25–28 June 2018

Three occlusion processing techniques for computer-generated holography are proposed to support layer-based methods of acquiring holograms from point clouds. The techniques use Gaussian masks and masks generated by dilation per point or per layer.

Performance Evaluation of Sparseness Significance Ranking Measure (SSRM) on Holographic Content

Ayyoub Ahar, Tobias Birnbaum, David Blinder, Athanasia Symeonidou, and Peter Schelkens
Conference Papers Digital Holography and Three-Dimensional Imaging 2018, 25–28 June 2018

The Sparseness Significance Ranking Measure (SSRM) was recently proposed as full reference quality measure for regular images. In this paper, we evaluate its performance on holographic content in comparison to MSE, PSNR and the Versatile Similarity Measure (VSM). The experimental results based on subjective quality assessment show a significant gain over the classical methods.

Source coding of holographic data: challenges, algorithms and standardization efforts

Peter Schelkens, David Blinder, Tobias Birnbaum, Athanasia Symeonidou, Ayyoub Ahar, Colas Schretter
Conference Papers Proceedings Volume 10834, Speckle 2018: VII International Conference on Speckle Metrology; 108340Y (2018)

Holographic imaging modalities are gaining increasing interest in various application domains ranging from microscopy to high-end autostereoscopic displays. While much effort has been spent on the development of the optics, photonics and micro/nano-electronics that enable the design of holographic capturing and visualization devices, relatively few research effort has been targeted towards the underlying signal processing. One significant challenge relates to the fact that the data volumes needed in support of this kind of holographic applications is rapidly increasing: for visualization devices, and in particular holographic displays, unprecedented resolutions are desired resulting in huge bandwidth requirements on both the communication channels and internal computing and data channels. An additional challenge relates to the fact that we are handling an interference-based modality being complex amplitude based in nature. Both challenges lead to the fact that for example classic data representations and coding solutions fail to handle holographic data in an effective way. This paper attempts to provide some insights that enable to alleviate or a least reduce these bottlenecks and sketch an avenue for the development of efficient source coding solutions. Moreover, it will also outline the efforts the JPEG committee is undertaking in the context of the JPEG Pleno standardization programme to roll out a path for data interoperability of holographic solutions.

A Roadmap Towards Holographic Television From a Signal Processing Perspective

Peter Schelkens, Ayyoub Ahar, Stijn Bettens, Vitaliy Bilous, Tobias Birnbaum, David Blinder, Heidi Ottevaere, Adrian Munteanu, Colas Schretter, and Athanasia Symeonidou
Conference Papers Digital Holography and Three-Dimensional Imaging 2017, 29 May - 1 June 2017

In recent years, the domain of plenoptic imaging has seen significant scientific and industrial evolutions. We present novel signal processing technologies addressing holographic imaging, ranging from capture to rendering of complex amplitude digital holograms.

Computer-generated holograms by multiple wavefront recording plane method with occlusion culling

Athanasia Symeonidou, David Blinder, Adrian Munteanu, Peter Schelkens
Journal Paper Optics Express 23, p. 22149-22161, Aug 2015

We propose a novel fast method for full parallax computer-generated holograms with occlusion processing, suitable for volumetric data such as point clouds. A novel light wave propagation strategy relying on the sequential use of the wavefront recording plane method is proposed, which employs look-up tables in order to reduce the computational complexity in the calculation of the fields. Also, a novel technique for occlusion culling with little additional computation cost is introduced. Additionally, the method adheres a Gaussian distribution to the individual points in order to improve visual quality. Performance tests show that for a full-parallax high-definition CGH a speedup factor of more than 2,500 compared to the ray-tracing method can be achieved without hardware acceleration.

Three-dimensional rendering of computer-generated holograms acquired from point-clouds on light field displays

Athanasia Symeonidou, David Blinder, Adrian Munteanu, Peter Schelkens
Conference Papers Proc. SPIE 9971, Applications of Digital Image Processing XXXIX, Oct 2016

Holograms, either optically acquired or simulated numerically from 3D datasets, such as point clouds, have special rendering requirements for display. Evaluating the quality of hologram generation techniques is not straightforward, since high-quality holographic display technologies are still immature, despite the technological advances in 3D display. In this paper we present a framework for three-dimensional rendering of colour computer-generated holograms (CGHs) acquired from point-clouds, on high-end light field displays. This allows for the rendering of holographic content with horizontal parallax and wide viewing angle. We deploy prior work, namely a fast CGH method that inherently handles occlusion problems to acquire high quality colour holograms from point clouds. Our experiments showed that rendering holograms with the framework proposed provides 3D effect with depth disparity and horizontal-only or full parallax with wide viewing angle. Therefore, it allows for the evaluation of CGH techniques regarding functional properties such as depth cues and efficient occlusion handling.

Speckle noise reduction for computer generated holograms of objects with diffuse surfaces

Athanasia Symeonidou, David Blinder, Ayyoub Ahar, Colas Schretter, Adrian Munteanu, Peter Schelkens
Conference Papers Proc. SPIE 9686, Optics, Photonics and Digital Technologies for Multimedia Applications IV, May 2016

Digital holography is mainly used today for metrology and microscopic imaging and is emerging as an important potential technology for future holographic television. To generate the holographic content, computer-generated holography (CGH) techniques convert geometric descriptions of a 3D scene content. To model different surface types, an accurate model of light propagation has to be considered, including for example, specular and diffuse reflection. In previous work, we proposed a fast CGH method for point cloud data using multiple wavefront recording planes, look-up tables (LUTs) and occlusion processing. This work extends our method to account for diffuse reflections, enabling rendering of deep 3D scenes in high resolution with wide viewing angle support. This is achieved by modifying the spectral response of the light propagation kernels contained by the look-up tables. However, holograms encoding diffuse reflective surfaces depict significant amounts of speckle noise, a problem inherent to holography. Hence, techniques to improve the reduce speckle noise are evaluated in this paper. Moreover, we propose as well a technique to suppress the aperture diffraction during numerical, view-dependent rendering by apodizing the hologram. Results are compared visually and in terms of their respective computational efficiency. The experiments show that by modelling diffuse reflection in the LUTs, a more realistic yet computationally efficient framework for generating high-resolution CGH is achieved.

Open Access Database for Experimental Validations of Holographic Compression Engines

David Blinder, Ayyoub Ahar, Athanasia Symeonidou, Yafei Xing, Tim Bruylants, Colas Schretter, Beatrice Pesquet-Popescu, Frederic Dufaux, Adrian Munteanu, Peter Schelkens
Conference Papers Quality of Multimedia Experience (QoMEX), 2015 Seventh International Workshop on, p.1-6, 26-29 May 2015

Holography allows for both the recording and reproduction of wavefields of light, and is thereby able to fully capture the three-dimensional structure of objects. The appearance of the object will change according to the position and orientation of the viewer, providing an immersive experience as if objects are actually present. Moreover, holograms have many applications in metrology such as microscopy and interferometry. Because holograms represent interference patterns, they possess significantly different signal properties from natural photography and video; this will make conventional image encoders perform sub-optimally on holograms. Therefore, new data compression techniques have to be evaluated for this type of data. One important requirement for comparing and evaluating various codecs is to have reference holograms which are publicly available. For this purpose, we have set up an open public database containing a set of computer-generated holograms. Furthermore, we evaluate the performances of two JPEG 2000-based coders, which were modified to better cope with holographic data.

A novel microstrip antenna array with metamaterial-based electronic beam steering at 2.4 GHz

Athanasia Symeonidou, Katherine Siakavara
Journal Paper Progress In Electromagnetics Research C, Vol. 38, 27-42, Mar 2013

A metamaterial-based electronically-controlled microstrip structure, performing as leaky wave (LW) antenna with beam steering capability was synthesized. The structure has the configuration of metamaterial transmission line (TL) composed of cascade composite right-/left-handed (CRLH) unit cells. The direction of maximum radiation is tuned via the variation of varactros' capacities incorporated to the structure. Theoretical analysis and synthesis, based on the metamaterial TL theory, was made and novel methods to realize some of the elements of the units cells are proposed. Results, received via simulation, demonstrate that the LW antenna has steering capability of the direction of maximum radiation in a range of 40°, gain changing a little, 6 dB to 7 dB, during the scanning, whereas small number of cells is enough to obtain this performance.

Microstrip beam scan antenna design on the approach of metamaterials’ structure

Athanasia Symeonidou
Jury members: Katherine Siakavara (Supervisor), Elias Vafeiadis, Theodoros Samaras
Master Thesis Aristotle university of Thessaloniki | October, 2012

The aim of this thesis is to design microstrip antenna for mobile communication devices in the 2.4 GHz band with the ability to control the direction of the maximum emission of the antenna operationally and in real time. The antenna consists of a repetitive periodic structure synthesized via the approach of artificial metamaterials to the theory of transmission lines.

Chapter 1 introduces the idea of metamaterials, gives a recursion in their historical development, while some applications are listed. Also, the approach of metamaterials according to the theory of transmission lines is described. Chapter 2 is devoted to microstrip patch antennas. Their basic characteristics, the most common feeding techniques, as well as their advantages and disadvantages are listed. Chapter 3 presents analytically the method followed to design the microstrip antenna from scratch. Starting with the design of the unit transmission line (1 cell) until the final proposed antenna. Chapter 4 discusses the results of the simulations of the antenna designed and enhances the function of the structure as a metamaterial. Chapter 5 summarizes the results of the simulations of some alternative structures and compares the results with the proposed structure of Chapter 4. Finally, Chapter 6 summarizes the conclusions of this thesis and the research made and suggests topics for future research.

Talks, demos and presentations

  • Speaker 9 Nov 2019

    Les garages numeriques 2019

    Presentation title: "Holograms in art and science"

    Explaining the basics of holography motivated by the collection of holograms of artist Louise Bourgeois and the scientific research done on holography at ETRO (VUB).

    Ohme curated ]unframed[, an ArtScience programme in the framework of Les Garages Numériques Festival 2019. The ]unframed[ series unfolds in multiple moments spread over two days, through a panel talk (7 November), a series of talks & lectures, the archipelago of close ups and two performances (9 November). Theorists, educators, programmers, artists and scientists together for a series of talks, lectures and performances around artistic practice and scientific knowledge.

    La Bourse, Brussels, Belgium

    Ohme, https://www.lesgaragesnumeriques.com/

  • Exhibitor 23-24 May 2019

    ITF2018 Belgium

    Co-hosting our demo booth on "Computer-genarated holograms"

    Antwerp, Belgium

    imec, https://www.imectechnologyforum.com/itf2018belgium

  • Speaker 26 Jun 2018

    OSA Digital Holography and Three-Dimensional Imaging 2018

    Presentation title: "Occlusion culling techniques for layer-based computer-generated holography"

    Orlando, FL, United States

    OSA, https://www.osa.org/en-us/meetings/osa_meetings/osa_imaging_and_applied_optics_congress/program/digital_holography_and_three-dimensional_imaging/

  • Speaker 29 Aug 2016

    SPIE Optics + Photonics 2016

    Presentation title: "Three-dimensional rendering of computer-generated holograms acquired from point-clouds on light field displays"

    San Diego, CA, Unites States

    SPIE, https://spie.org/conferences-and-exhibitions/optics-and-photonics?SSO=1

  • Speaker 03 Apr 2016

    SPIE Photonics Europe 2016

    Presentation title: "Speckle noise reduction for computer generated holograms of objects with diffuse surfaces"

    Best Student Paper Award at the "Optics, Photonics and Digital Technologies for Imaging Applications IV" conference

    Brussels, Belgium

    SPIE, http://spie.org/conferences-and-exhibitions/photonics-europe

Teaching experience

  • 2015 2018

    Image Processing


    Professor: Prof. Adrian Munteanu (titular)
    Teaching assistants: Athanasia Symeonidou, Andrei Sechelea
    Language: English
    Credits: 5 ECTS
    Course info: ULB website
    Wrote teaching material for the course “Image Processing" (MSc of VUB/ULB bruface)
    Taught the exercise sessions
    Organized the exercise sessions
    Assigned, supervised and graded the term projects for 50 students yearly

  • 2016 2017

    Supervision of a Master thesis

    Title: "Optimizing Computer-Generated Holography from Point Clouds using GPU Parallelization" by Fernando Suarez Groen

Where to find me