Dronument

Aerial Autonomy for Documentation of Historical Monuments

   The official project site in the Czech language: dronument.cz

Documenting structural and cultural artifacts within the interiors of historical buildings is a challenging and exhausting task since most of the areas of interest are beyond typical human reach. We advocate the use of autonomous teams of multi-rotor Unmanned Aerial Vehicles (UAVs) to speed up the documentation process by several orders of magnitude while allowing for an autonomous solution capable of repeatable and accurate collision-free operation at great heights. The Dronument technology can perform single-UAV tasks with different sensors (high-resolution camera, laser scanner) and allows for multi-UAV cooperation in tasks requiring dynamic scene illumination in real-world scenarios, a process previously applicable only in small-scale laboratory-like conditions.
 

Our experimental deployments range from single-UAV imaging to specialized lighting techniques (visible, IR, UV) requiring accurate coordination of multiple UAVs. The technology has been used in 17 historical structures, where it was to this day deployed in more than 12 hours of autonomous flying to document cultural (paintings, altars, statues, mosaics, frescoes, stained glass, pillars, pipe organs) and structural elements (wall clefts) without access to GPS.

This multidisciplinary project results from the cooperation of roboticists from the Multi-Robot Systems group (MRS) and restorers and conservators from the Czech Heritage Institute. The Czech Ministry of Culture approved the Dronument methodology (in Czech only, English summary available in article New Era in Cultural Heritage Preservation) for using UAVs in interior documentation. This methodology specifies numerous lessons transferable to other safety-critical robotic missions in documentation and inspection tasks.

Project results

  • Interactive 3D models of some of the documented historical sites are available at mrs.felk.cvut.cz/3d-model-viewer.
  • Project outputs (Nmet, Npam, Nmaps) are available (in Czech only) at dronument.cz/vystupy.
  • Public workshop on September 12, 2021: video record (~3.5h incl. presentation of Dronument and real example of the UAV system).
  • Document The hidden places of St. Moritz Church in Olomouc, video (5m 25s).
  • Document Chateau Plumlov and its historical secrets from the bird's eye view, video (5m 10s)
  • Functional sample of the UAV platform: description in Czech, 3D model.
  • The project was part of the Czech Pavilion at EXPO2020 in Dubai.

List of documented historical sites

Archbishop’s Chateau Kroměříž (UNESCO World Heritage)

Saint Nicolas Church at Old Town Square in Prague

Church of St. Maurice in Olomouc (interior 3-D model, facade 3-D model)

Plumlov Chateau (3-D model: south, north facade)

St. Jacob the Great and St. Anne Church in Stará Voda (3-D model)

Vranov nad Dyjí State Chateau

Klein Family Mausoleum in Sobotín (3-D model)

St. Mary Magdalene Chapel in Jindřichův Hradec

Chapel of All Saints in Chateau Telč (UNESCO World Heritage)

Church of our Lady of the Snows in Olomouc

Church of the Exaltation of the Holy Cross in Prostĕjov

Church of the Holy Trinity in Kopřivná

Church of St. Bartholomew in Zábřeh

Church of the Nativity of the Virgin Mary in Nový Malín

Church of St. Mary Magdalene in Chlumín

Church of the Assumption of the Virgin Mary in Cholina

Church of the Holy Trinity in Běhařovice

Church of Saint Barbara in Šumperk

Church of the Annunciation of Virgin Mary Šternberk

Grotto Gorzanów

Publications

  1. Pavel Petracek, Vit Kratky, Tomas Baca, Petrlik Matej and Martin Saska. New Era in Cultural Heritage Preservation: Cooperative Aerial Autonomy for Fast Digitalization of Difficult-to-Access Interiors of Historical Monuments. IEEE Robotics and Automation Magazine ():2–19, February 2023. PDF, DOI BibTeX

    @article{petracek2023ram,
	author = "Petracek, Pavel and Kratky, Vit and Baca, Tomas and Petrlik, Matej, and Saska, Martin",
	journal = "IEEE Robotics and Automation Magazine",
	title = "{New Era in Cultural Heritage Preservation: Cooperative Aerial Autonomy for Fast Digitalization of Difficult-to-Access Interiors of Historical Monuments}",
	year = 2023,
	volume = "",
	number = "",
	pages = "2--19",
	month = "February",
	doi = "10.1109/MRA.2023.3244423",
	pdf = "data/papers/petracek2023ram.pdf"
}

  2. P Petráček, V Krátký and M Saska. Dronument: System for Reliable Deployment of Micro Aerial Vehicles in Dark Areas of Large Historical Monuments. IEEE Robotics and Automation Letters 5(2):2078-2085, April 2020. PDF, DOI BibTeX

    @article{petracek2020ral,
	author = "P. {Petr\'{a}\v{c}ek} and V. {Kr\'{a}tk\'{y}} and M. {Saska}",
	journal = "IEEE Robotics and Automation Letters",
	title = "Dronument: System for Reliable Deployment of Micro Aerial Vehicles in Dark Areas of Large Historical Monuments",
	year = 2020,
	volume = 5,
	number = 2,
	pages = "2078-2085",
	keywords = "Aerial systems: applications; Aerial systems: Perception and autonomy;Localization",
	doi = "10.1109/LRA.2020.2969935",
	issn = "2377-3774",
	month = "April",
	pdf = "data/papers/petracek2020ral.pdf"
}

  3. V Krátký, P Petráček, V Spurný and M Saska. Autonomous Reflectance Transformation Imaging by a Team of Unmanned Aerial Vehicles. IEEE Robotics and Automation Letters 5(2):2302-2309, April 2020. PDF, DOI BibTeX

    @article{kratky2020ral,
	author = "V. {Kr\'{a}tk\'{y}} and P. {Petr\'{a}\v{c}ek} and V. {Spurn\'{y}} and M. {Saska}",
	journal = "IEEE Robotics and Automation Letters",
	title = "Autonomous Reflectance Transformation Imaging by a Team of Unmanned Aerial Vehicles",
	year = 2020,
	volume = 5,
	number = 2,
	pages = "2302-2309",
	doi = "10.1109/LRA.2020.2970646",
	month = "April",
	pdf = "data/papers/kratky2020ral.pdf"
}

  4. M Saska, V Krátký, V Spurný and T Báča. Documentation of dark areas of large historical buildings by a formation of unmanned aerial vehicles using model predictive control. In 2017 22nd IEEE International Conference on Emerging Technologies and Factory Automation (ETFA). 2017, 1–8. URL PDF, DOI BibTeX

    @inproceedings{saska2017etfa,
	author = "M. Saska and V. Kr\'{a}tk\'{y} and V. Spurn\'{y} and T. B\'{a}\v{c}a",
	booktitle = "2017 22nd IEEE International Conference on Emerging Technologies and Factory Automation (ETFA)",
	title = "Documentation of dark areas of large historical buildings by a formation of unmanned aerial vehicles using model predictive control",
	year = 2017,
	pages = "1--8",
	doi = "10.1109/ETFA.2017.8247654",
	url = "http://ieeexplore.ieee.org/document/8247654/",
	pdf = "data/papers/saska17etfa.pdf",
	month = "Sep."
}

  5. Vít Krátký, Pavel Petráček, Tiago Nascimento, Michaela Čadilová, Milan Škobrtal, Pavel Stoudek and Martin Saska. Safe Documentation of Historical Monuments by an Autonomous Unmanned Aerial Vehicle. ISPRS International Journal of Geo-Information 10(11):738/1–16, October 2021. PDF, DOI BibTeX

    @article{kratky2021documentation,
	author = "Krátký, Vít and Petráček, Pavel and Nascimento, Tiago and Čadilová, Michaela and Škobrtal, Milan and Stoudek, Pavel and Saska, Martin",
	title = "Safe Documentation of Historical Monuments by an Autonomous Unmanned Aerial Vehicle",
	journal = "ISPRS International Journal of Geo-Information",
	volume = 10,
	year = 2021,
	month = "October",
	number = 11,
	pages = "738/1--16",
	issn = "2220-9964",
	pdf = "data/papers/kratky2021dronument.pdf",
	doi = "10.3390/ijgi10110738"
}

  6. Milan Škobrtal, Aneta Škobrtal Zlámalová, Vít Krátký and Petráček Pavel. Průzkum malby Zvěstování Panny Marie v poutním chrámu ve Staré Vodě u Libavé pomocí bezpilotní helikoptéry. Památky 1(4):16–33, 2022. BibTeX

    @article{skobrtal2022pamatky,
	author = "Škobrtal, Milan and Škobrtal Zlámalová, Aneta and Krátký, Vít and Petráček Pavel",
	journal = "Památky",
	title = "{Průzkum malby Zvěstování Panny Marie v poutním chrámu ve Staré Vodě u Libavé pomocí bezpilotní helikoptéry}",
	year = 2022,
	volume = 1,
	number = 4,
	pages = "16--33"
}

  7. Daniel Smrcka, Tomas Baca, Tiago Nascimento and Martin Saska. Admittance Force-Based UAV-Wall Stabilization and Press Exertion for Documentation and Inspection of Historical Buildings. In 2021 International Conference on Unmanned Aircraft Systems (ICUAS). June 2021, 552–559. PDF, DOI BibTeX

    @inproceedings{smrcka2021admittance,
	title = "Admittance Force-Based UAV-Wall Stabilization and Press Exertion for Documentation and Inspection of Historical Buildings",
	author = "Smrcka, Daniel and Baca, Tomas and Nascimento, Tiago and Saska, Martin",
	booktitle = "2021 International Conference on Unmanned Aircraft Systems (ICUAS)",
	pages = "552--559",
	year = 2021,
	month = "June",
	organization = "IEEE",
	pdf = "data/papers/ICUAS_2021_Dan.pdf",
	doi = "10.1109/ICUAS51884.2021.9476873"
}

  8. Vít Krátký, Alfonso Alcántara, Jesús Capitán, Petr Štěpán, Martin Saska and Aníbal Ollero. Autonomous Aerial Filming with Distributed Lighting by a Team of Unmanned Aerial Vehicles. IEEE Robotics and Automation Letters 6(4):7580-7587, October 2021. PDF, DOI BibTeX

    @article{kratky2021aerialfilming,
	author = "{Krátký}, Vít and {Alcántara}, Alfonso and {Capitán}, Jesús and {Štěpán}, Petr and {Saska}, Martin and {Ollero}, Aníbal",
	title = "{Autonomous Aerial Filming with Distributed Lighting by a Team of Unmanned Aerial Vehicles}",
	journal = "IEEE Robotics and Automation Letters",
	year = 2021,
	month = "October",
	pdf = "data/papers/aerialCinematographyRal.pdf",
	doi = "10.1109/LRA.2021.3098811",
	pages = "7580-7587",
	volume = 6,
	number = 4
}

  9. Jindřiška Deckerová, Jan Faigl and Vít Krátký. Traveling Salesman Problem with neighborhoods on a sphere in reflectance transformation imaging scenarios. Expert Systems with Applications 198:116814, March 2022. PDF, DOI BibTeX

    @article{deckerova2022tspns,
	author = "Deckerová, Jindřiška and Faigl, Jan and Krátký, Vít",
	title = "{Traveling Salesman Problem with neighborhoods on a sphere in reflectance transformation imaging scenarios}",
	journal = "Expert Systems with Applications",
	volume = 198,
	pages = 116814,
	year = 2022,
	month = "March",
	issn = "0957--4174",
	doi = "10.1016/j.eswa.2022.116814",
	pdf = "https://www.sciencedirect.com/science/article/pii/S0957417422002718?via=ihub"
}

  10. V Walter, N Staub, A Franchi and M Saska. UVDAR System for Visual Relative Localization With Application to Leader–Follower Formations of Multirotor UAVs. IEEE Robotics and Automation Letters 4(3):2637–2644, July 2019. PDF, DOI BibTeX

    @article{uvdar_dirfol,
	author = "V. {Walter} and N. {Staub} and A. {Franchi} and M. {Saska}",
	journal = "IEEE Robotics and Automation Letters",
	title = "{UVDAR System for Visual Relative Localization With Application to Leader–Follower Formations of Multirotor UAVs}",
	year = 2019,
	volume = 4,
	number = 3,
	pages = "2637--2644",
	doi = "10.1109/LRA.2019.2901683",
	issn = "2377--3766",
	month = "July",
	pdf = "data/papers/walterRAL2019.pdf"
}

  11. V Walter, N.Staub, M Saska and A Franchi. Mutual Localization of UAVs based on Blinking Ultraviolet Markers and 3D Time-Position Hough Transform. In 14th IEEE International Conference on Automation Science and Engineering (CASE 2018). 2018. PDF BibTeX

    @inproceedings{uvdd2,
	author = "V. Walter and N.Staub and M. Saska and A. Franchi",
	title = "{Mutual Localization of UAVs based on Blinking Ultraviolet Markers and 3D Time-Position Hough Transform}",
	booktitle = "14th IEEE International Conference on Automation Science and Engineering (CASE 2018)",
	pdf = "data/papers/uvdd2.pdf",
	year = 2018
}

  12. Vaclav Pritzl, Matous Vrba, Petr Stepan and Martin Saska. Cooperative Navigation and Guidance of a Micro-Scale Aerial Vehicle by an Accompanying UAV using 3D LiDAR Relative Localization. In 2022 International Conference on Unmanned Aircraft Systems (ICUAS). June 2022, 526–535. PDF, DOI BibTeX

    @inproceedings{pritzl2022icuas,
	author = "{Pritzl}, Vaclav and {Vrba}, Matous and {Stepan}, Petr and {Saska}, Martin",
	booktitle = "{2022 International Conference on Unmanned Aircraft Systems (ICUAS)}",
	title = "{Cooperative Navigation and Guidance of a Micro-Scale Aerial Vehicle by an Accompanying UAV using 3D LiDAR Relative Localization}",
	year = 2022,
	month = "June",
	organization = "IEEE",
	pdf = "data/papers/ICUAS22_Pritzl.pdf",
	pages = "526--535",
	doi = "10.1109/ICUAS54217.2022.9836116"
}

  13. Jan Bednar, Matej Petrlik, Kelen Cristiane Teixeira Vivaldini and Martin Saska. Deployment of Reliable Visual Inertial Odometry Approaches for Unmanned Aerial Vehicles in Real-world Environment. In 2022 International Conference on Unmanned Aircraft Systems (ICUAS). June 2022. PDF, DOI BibTeX

    @inproceedings{BednarICUAS22_VIO,
	author = "{Bednar}, Jan and {Petrlik}, Matej and {Teixeira Vivaldini}, Kelen Cristiane and {Saska}, Martin",
	booktitle = "2022 International Conference on Unmanned Aircraft Systems (ICUAS)",
	title = "{Deployment of Reliable Visual Inertial Odometry Approaches for Unmanned Aerial Vehicles in Real-world Environment}",
	year = 2022,
	month = "June",
	organization = "IEEE",
	doi = "10.1109/ICUAS54217.2022.9836067",
	pdf = "data/papers/ICUAS22_VIO_Bednar.pdf"
}

  14. T Musil, Matej Petrlik and Martin Saska. SphereMap: Dynamic Multi-Layer Graph Structure for Rapid Safety-Aware UAV Planning. IEEE Robotics and Automation Letters 7(4):11007-11014, 2022. PDF, DOI BibTeX

    @article{musil2022spheremap,
	author = "T. Musil and Petrlik, Matej and Saska, Martin",
	journal = "IEEE Robotics and Automation Letters",
	title = "{SphereMap: Dynamic Multi-Layer Graph Structure for Rapid Safety-Aware UAV Planning}",
	year = 2022,
	volume = 7,
	number = 4,
	pages = "11007-11014",
	pdf = "data/papers/musil2022ral.pdf",
	doi = "10.1109/LRA.2022.3195194"
}

  15. Daniel Hert, Tomas Baca, Pavel Petracek, Vit Kratky, Vojtech Spurny, Matej Petrlik, Matous Vrba, David Zaitlik, Pavel Stoudek, Viktor Walter, Petr Stepan, Jiri Horyna, Vaclav Pritzl, Giuseppe Silano, Daniel Bonilla Licea, Petr Stibinger, Robert Penicka, Tiago Nascimento and Martin Saska. MRS Modular UAV Hardware Platforms for Supporting Research in Real-World Outdoor and Indoor Environments. In 2022 International Conference on Unmanned Aircraft Systems (ICUAS). June 2022, 1264–1273. PDF, DOI BibTeX

    @inproceedings{MRS2022ICUAS_HW,
	author = "{Hert}, Daniel and {Baca}, Tomas and {Petracek}, Pavel and {Kratky}, Vit and {Spurny}, Vojtech and {Petrlik}, Matej and {Vrba}, Matous and {Zaitlik}, David and {Stoudek}, Pavel and {Walter}, Viktor and {Stepan}, Petr and {Horyna}, Jiri and {Pritzl}, Vaclav and {Silano}, Giuseppe and {Bonilla Licea}, Daniel and {Stibinger}, Petr and {Penicka}, Robert and {Nascimento}, Tiago and {Saska}, Martin",
	booktitle = "2022 International Conference on Unmanned Aircraft Systems (ICUAS)",
	title = "{MRS Modular UAV Hardware Platforms for Supporting Research in Real-World Outdoor and Indoor Environments}",
	year = 2022,
	month = "June",
	organization = "IEEE",
	pdf = "data/papers/ICUAS22_MRS_HW.pdf",
	pages = "1264--1273",
	doi = "10.1109/ICUAS54217.2022.9836083"
}

  16. D Hert, T Baca, P Petracek, V Kratky, R Penicka, V Spurny, M Petrlik, M Vrba, D Zaitlik, P Stoudek, V Walter, P Stepan, J Horyna, V Pritzl, M Sramek, A Ahmad, G Silano, D Bonilla Licea, P Stibinger, T Nascimento and M Saska. MRS Drone: A Modular Platform for Real-World Deployment of Aerial Multi-Robot Systems. Journal of Intelligent & Robotic Systems 108:1–34, July 2023. URL PDF, DOI BibTeX

    @article{HertJINTHW_paper,
	author = "{Hert}, D. and {Baca}, T. and {Petracek}, P. and {Kratky}, V. and {Penicka}, R. and {Spurny}, V. and {Petrlik}, M. and {Vrba}, M. and {Zaitlik}, D. and {Stoudek}, P. and {Walter}, V. and {Stepan}, P. and {Horyna}, J. and {Pritzl}, V. and {Sramek}, M. and {Ahmad}, A. and {Silano}, G. and {Bonilla Licea}, D. and {Stibinger}, P. and {Nascimento}, T. and {Saska}, M.",
	month = "July",
	title = "{MRS Drone: A Modular Platform for Real-World Deployment of Aerial Multi-Robot Systems}",
	year = 2023,
	journal = "Journal of Intelligent {\&} Robotic Systems",
	publisher = "Springer",
	pdf = "data/papers/JINT2023Hert.pdf",
	volume = 108,
	pages = "1--34",
	doi = "10.1007/s10846-023-01879-2",
	issue = 64,
	url = "https://link.springer.com/article/10.1007/s10846-023-01879-2"
}

Secondary research activities

Partners

Územní odborné pracoviště NPÚ in Olomouc (Heritage Institute)

Fakulta restaurování, University of Pardubice (Faculty of restoration)

Project results in News

Olomoucký sloup zapsaný v UNESCO čeká obnova, před ní ho nasnímal dron   IDnes [Czech]
Drony mapují interiéry vzácných památek. Čeští vědci si připsali světové prvenství   Krajské listy [Czech]
Drony ČVUT mapují jako první na světě útroby památek. V plánu byl i Černobyl   Seznam zprávy [Czech]
Drony z ČVUT mapují kostel sv. Mořice   Olomouc.cz [Czech]
ČVUT: Drony z Fakulty elektrotechnické mapují kostel sv. Mořice v Olomouci   Parlamentni listy [Czech]
V chrámu ve Staré Vodě na Libavé se roztočily vrtule projektu Dronument   iDNES.cz [Czech]
Kostel ve Staré Vodě na Libavé mapovaly inteligentní bezpilotní drony   Seznam zprávy [Czech]
Drony v kostele sv. Anny a sv. Jakuba Většího ve Staré Vodě (začátek v 1h20min)   90' ČT [Czech]
Drony v kostele sv. Anny a sv. Jakuba Většího ve Staré Vodě (začátek v 47min)   90' ČT [Czech]
Dron létá sám do nepřístupných míst. Pomáhá mapovat historické objekty   Novinky.cz [Czech]
Tým z ČVUT představil dron mapující špatně přístupná místa památek   ČTK [Czech]
Co památkářům trvá měsíce, dokážou za den. Interiér barokního kostela ve Staré Vodě mapují drony   Český rozhlas Radiožurnál [Czech]
VIDEO: Barokním kostelem v Libavé létají drony. Prozkoumávají těžko dostupná místa   iRozhlas [Czech]
GALLERY: Czech-made robot drones help map rare historical objects   Expats [English]
Svatostánky dron prozkoumá lépe. Ušetří čas i peníze   Deník Metro [Czech]
Drones al servicio de conservacionistas de monumentos históricos   Radio Prague International [Spanish]
V chrámu ve Staré Vodě na Libavé se roztočily vrtule projektu Dronument   24 Zprávy [Czech]
Co památkářům trvá měsíce, dokážou za den. Interiér barokního kostela ve Staré Vodě mapovaly inteligentní drony   Český rozhlas Olomouc [Czech]
Drony v kupoli kostela   Události ČT [Czech]
Drony dokumentují interiéry kostela ve Staré Vodě (min 18:00)   CNN Prima News [Czech]
Robotické drony z ČVUT snímají interiéry kostelů a zámků, vystačí si samy, žádný operátor je řídit nemusí         Euro.cz [Czech]
Robotické drony z Fakulty elektrotechnické ČVUT pomáhají mapovat historické objekty         Technický týdeník [Czech]
Robotické drony pomáhají mapovat historické objekty         SCIENCEmag [Czech]
V chrámu ve Staré Vodě na Libavé se roztočily vrtule projektu Dronument         IDNES.cz [Czech]
Kostel ve Staré Vodě na Libavé mapovaly inteligentní bezpilotní drony         Olomoucká drbna [Czech]
Kostel ve Staré Vodě na Libavé mapovaly inteligentní bezpilotní drony         ČTK České noviny [Czech]
Drony pomáhají památkářům, na dálku dokážou změřit i vlhkost vzduchu         ČT24 [Czech]
Robotics and conservation experts turn to drones to map state of historic sites         Interview for Czech radio [English]
Zmapování stavu památek díky dronům   Main news of Czech TV [Czech]
CT 24 Pryč s lešením, budoucnost památek leží na křídlech dronů   Czech TV news [Czech]
Dron jako pomůcka památkářů. Inovátoři nemyslí jen na budoucnost, ale i minulost   www.ceskatelevize.cz [Czech]
Drony mapovaly kostel sv. Mikuláše v Praze   Main News of Czech TV [Czech]
Drony mapovaly kostel sv. Mikuláše   Live 10 min reportage at Czech TV [Czech]
Drony zblízka zjistí stav památek na špatně dostupných místech   Czech radio [Czech]
Drony se dostanou skutečně všude, momentálně pomáhají památkářům   Czech radio [Český rozhlas] PLUS [Czech]
Drony zjistí stav památek na špatně dostupných místech   Týden [Czech]
Drony zblízka zjistí stav památek na špatně dostupných místech   Blesk [Czech]
Kam člověk nemůže, tam nastrčí... helikoptérku. Bezpilotní drony pomáhají mapovat stav památek ve šternberské farnosti   www.krajskelisty.cz/ [Czech]
Robotici z Fakulty elektrotechnické ČVUT pomáhají památkářům mapovat historické objekty   www.itbiz.cz [Czech]
Robotici z ČVUT mapují historické objekty pomocí dronů   aktualnizpravy.cz [Czech]
Dron jako pomůcka památkářů. Inovátoři nemyslí jen na budoucnost, ale i minulost   www.regionplzen.cz [Czech]
Dron může pomoci identifikovat sochy v kostele sv. Mikuláše   ČTK [Czech]
Drony vědců z ČVUT fotí těžko přístupná místa v kostelích. Pomohou kunsthistorikům i restaurátorům   Hospodářské noviny [Czech]
Drony z ČVUT zmapovaly kostel sv. Mikuláše   SCIENCEmag.cz [Czech]
ABC TV: České drony v chrámu sv. Mikuláše slouží vědě   ABC [Czech]
Drony v kostele mapovaly těžce přístupná místa   Czech Radio [Český rozhlas] [Czech]
Dron může pomoci identifikovat sochy v kostele sv. Mikuláše   Blesk [Czech]
Robotici z ČVUT mapují historické objekty pomocí dronů   21. století [Czech]
Drony zblízka zjistí stav památek na špatně dostupných místech   PRO PAMÁTKY [Czech]
Tým z ČVUT učí drony, jak létat bez vedení pilotem. Stroje tak můžou dokumentovat historické objekty   Hospodářské noviny [Czech]

 

 Acknowledgment

 

    This research was/is supported by project NAKI II no. DG18P02OVV069, CTU grant no. SGS17/187/OHK3/3T/13, and project CESNET.