Viktoria Kristollari

Remote Sensing and Machine Learning Engineer, DEng.

Remote Sensing and Machine Learning researcher specializing in deep learning techniques for multispectral and hyperspectral remote sensing applications. Actively participated in drafting proposals for European and Greek research funding initiatives and successfully contributed to various image processing projects and employing a wide range of spectral data.

Authored and published multiple scientific papers, rigorously reviewed submissions for esteemed remote sensing journals, and gained experience as a teaching assistant supporting academic instruction in remote sensing topics.

Email email linkedin researchgate Google google scholar Orcid orcid Github github

Experience

National Technical University of Athens

Remote Sensing and Machine Learning researcher

June 2020 - June 2022

REACT Project: Crowdsourcing, Copernicus and Hyperspectral Satellite Data for Marine Plastic Litter Detection, Quantification and Tracking (funded by ESA).
Designed and implemented deep learning approaches for the pansharpening of PRISMA data and the fusion of Sentinel-2 and Worldview images.
Developed marine plastic litter indexes.
Project presentation: https://nebula.esa.int/content/remote-sensing-marine-litter-%E2%80%93-early-technology-development-scheme-react

February 2020 - December 2021

HYPERION Project: Development of a Decision Support System for Improved Resilience & Sustainable Reconstruction of historic areas to cope with Climate Change & Extreme Events based on Novel Sensors and Modelling Tools (Horizon 2020).
Developed land cover change maps through deep learning approaches.
Project website: https://www.hyperion-project.eu/

March 2020 - June 2020

ASTARTE Project: Analysis of SAR and thermal satellite data time-series for understanding the long-term impact of land surface temperature changes on forests.
Supervised the cloud masking process.
Project website: http://astarte.cut.ac.cy/project/

Feb 2019 - Jan 2025

National Technical University of Athens

Teaching Assistant

Course: "Special Topics of Remote Sensing".

Oct 2019 - Feb 2021

Marie Sklodowska-Curie Research and Innovation Staff Exchange

Remote Sensing and Machine Learning Researcher

Seconded researcher at CloudSigma (Sofia, Bulgaria), Planetek Italia (Bari, Italy), TWT (Stuttgart, Germany), i-Sea (Bordeaux, France). The secondments in each company lasted for 3 months.
Created cloud masks through deep learning approaches.

Jan 2018 - Jan 2019

Calcon GmbH

Remote Sensing and Machine Learning Annotator

Conducted field data collection utilizing HS VNIR and SWIR sensors.
Performed spectral analysis of urban construction materials and executed image data annotation for a Real Estate IT product.
Working remotely

March 2017 - Feb 2018

Full-body hyperspectral scanning

Scanning of psoriatic patients in a Greek dermatology clinic as part of the data collection of my diploma thesis.

October 2015 - May 2016

Geometric Documentation of the Temple of Haephestus

Semester Course (Monument Recording).
Creation of 3d model of the monument by photogrammetric methods and by use of laser point cloud.
Production of architectural drawings.

October 2014 - February 2015

Surveying Summer Internship

Topographic and cadastral survey of Sikinos island, Greece.
Use of a wide range of field surveying equipment.

July 2013

Topographic Survey in the Zografou campus of NTUA

Surveying Summer Course.

June 2012 - July 2012

Education

National Technical University of Athens

Doctor of Engineering

Subject title: Artificial Neural Networks for multispectral/hyperspectral earth observation data applications.

January 2018 - July 2024

National Technical University of Athens

Integrated Master

Rural, Surveying and Geoinformatics Engineering (ranked 2nd, Grade: 8.58/10)

Diploma Thesis title: "Automatic Hyperspectral Method for the Detection, Recognition and Scoring of Erythema in Psoriasis"
61 courses are required for the completion of studies. The following courses were among the courses that were completed:
- Digital Image Analysis for Remote Sensing
- Photogrammetry
- Geographical Information Systems
- Cartography
- Database Systems
- Programming
- Linear Algebra | Mathematical Analysis| Differential Equations | Probability and Statistics | Geometry (Descriptive,Perspective, Differential, Projective) | Numerical Analysis

October 2010 - July 2016

16th HIGH SCHOOL OF ATHENS

High School Diploma

Grade:19.6/20

2007 - 2010

Skills

Software

Languages

Greek (native)
English (level C2)
French (level B2)
German (level B2.1)
Albanian (B2)

Publications

-Kristollari V., and Karathanassi V. "NIR simulation by generative deep learning" (to be published).
[preprint]

-Kristollari V., "Unlocking the Potential of Artificial Intelligence for Satellite Image Processing" NTUA, PhD dissertation (2018-2024).
[NTUA access] [presentation]

-Karathanassi V., Karamvasis K., Kristollari V., Skamantzari M., and Georgopoulos A. "Remote sensing techniques for monitoring cultural heritage sites." In EGU General Assembly 2024, April 2024.
[abstract]

-Aiello A., Barbone E., Karathanassi V., Kolokoussis P., Kremezi M., Kristollari V., and Taggio N. "Unlocking the Potential of Spectral Signature Unmixing and Machine Learning for Detecting Plastic Marine Litter: Insights from the REACT Project." In ESA Remote Sensing of Marine Litter Workshop, October 2023.
[abstract]

-Kremezi M., Kristollari V., Karathanassi V., and Kolokoussis P. "Enhancing PRISMA and Sentinel 2 Capabilities for Marine Plastic Litter Detection Using Image Fusion Techniques, Spectral Signature Unmixing and Spectral Indexes." In 41st EARSeL Symposium, September 2022.
[researchgate access] [presentation] [abstract]

-Kremezi M., Kristollari V., Karathanassi V., Topouzelis K., Kolokoussis P., Taggio N., Aiello A., Ceriola G., Barbone E., and Corradi P. "Increasing the Sentinel-2 potential for marine plastic litter monitoring through image fusion techniques." Marine Pollution Bulletin 182 (2022): 113974.
[publisher access] [preprint] [related code]

-Taggio N., Aiello A., Ceriola G., Kremezi M, Kristollari V., Kolokoussis P., Karathanassi V., and Barbone E. " A Combination of Machine Learning Algorithms for Marine Plastic Litter Detection Exploiting Hyperspectral PRISMA Data." Remote Sensing 14, no. 15 (2022): 3606.
[publisher access] [researchgate access]

-Kristollari V., and Karathanassi V. "Change Detection in VHR Imagery With Severe Co-Registration Errors Using Deep Learning: A Comparative Study" IEEE Access 10 (2022): 33723-33741.
[publisher access] [researchgate access] [related code]

-Kremezi M., Kristollari V., Karathanassi V., Topouzelis K., Kolokoussis P., Taggio N., Aiello A., Ceriola G., Barbone B., and Corradi P. "Pansharpening PRISMA Data for Marine Plastic Litter Detection Using Plastic Indexes." IEEE Access 9 (2021): 61955-61971.
[publisher access>] [researchgate access] [related code]

-Kristollari V., and Karathanassi V. "Convolutional neural networks for detecting challenging cases in cloud masking using Sentinel-2 imagery." In Eighth International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2020), vol. 11524, p. 115240K. International Society for Optics and Photonics, 2020.
[publisher access] [researchgate access] [related code]

-Kristollari V., and Karathanassi V. "Fine-Tuning Self-Organizing Maps for Sentinel-2 Imagery: Separating Clouds from Bright Surfaces." Remote Sensing 12, no. 12 (2020): 1923.
[publisher access] [researchgate access] [related code]

-Kristollari V., and Karathanassi V. "Artificial neural networks for cloud masking of Sentinel-2 ocean images with noise and sunglint." International Journal of Remote Sensing 41, no. 11 (2020): 4102-4135.
[publisher access] [related code] [related dataset] [preprint]

-Kristollari V., "Automatic hyperspectral method for the detection, recognition and scoring of erythema in psoriasis" NTUA, Integrated Master thesis (2016).
[NTUA access]

-Kremezi M. and Kristollari V., "Accuracy assessment of the Agisoft Photoscan software" NTUA, technical report (2014).
[researchgate access] [presentation]

Honors & Awards

3 year scholarship awarded by the NTUA Special Account for Research Funds as a financial support for my PhD research (2017).
Limmat Stiftung Excellence Award (1 ^st prize, 2016)
Teenage member of the Greek Parliament (2009-2010)