Most important scientific results of the project group

  • Triglav Čekada, M., Adjova, L. (2023). Snowfield in Skedenj under Prisojnik from images. IN: Kuhar, M. (edt.), et al. Raziskave s področja geodezije in geofizike 2022 : zbornik del : 28. srečanje Slovenskega združenja za geodezijo in geofiziko, Ljubljana, 26. januar 2023. Ljubljana: Slovensko združenje za geodezijo in geofiziko, pp. 95-103, http://fgg-web.fgg.uni-lj.si/SUGG/referati/2023/SZGG_2023_TriglavCekada_Adjova.pdf  [COBISS.SI-ID 142652931]

The snowfield in Skedenj under Prisojnik, Slovenia, can be observed from one of the most crowded Alpine locations by tourists in Slovenia, from the Lake Jasna. That’s why, based on old photographs, postcards and our own photos, we have examined how its surface has changed over time. We looked at the long-term changes over several years, from 1906 to 2022, and the changes within the two melting seasons, i.e., over summers 2021 and 2022. The interactive method of orientation was used to process each photograph, also known as monoplotting. In total we used: 26 photographs or postcards, two Badjura’s maps of the Julian Alps from 1913 and 1922, five orthophotos of Cyclic Aerial Photographing of Slovenia and one national laser scanning from 2014. From 2007 to the present, the area of the snowfield at the end of August or mid-September is between 3 and 0.1 ha. The largest areas between 14.9 and 9.4 ha were measured in the period 1906 to 1956, but for these we do not know if postcards or maps of that time really show the snowfield at the end of the melting season.

  • Novak, N., Jesenko, D., Drešček, U., Triglav Čekada, M. (2022). Collecting voluntary photographs of topographic changes and the analysis of their usefulness. In: Breg Valjevec, M. et al (edt.). Preteklost in prihodnost (GIS v Sloveniji, 16, ISSN 1855-4954), pp. 321-332, DOI: https://doi.org/10.3986/9789610506683_26 [COBISS.SI-ID 124791811]

This paper presents three controlled campaigns for collecting volunteer photographs of topographic changes. We collected photographs of spatial changes that may be useful for the maintenance of the 1:5000 scale topographic map or the data of the so-called national topographic model. A total of 195 potential volunteers took part in those three volunteered geographic information (VGI) campaigns: all employees of the Geodetic Institute of Slovenia, part of the employees of UM FERI, two classes of students on UM FERI and three courses of students on UL FGG. A total of 62 volunteers responded to the call with 567 photographs showing 358 spatial changes (some individual changes were captured by several photographs; several volunteers photographed the same changes). The analysis of responses showed that in the groups where the participants were given no bonus, 26% of the potential volunteers responded. In the groups where they received a specific smaller bonus, the response rate was as high as 40%. The analysis of the potential usefulness of the photographs for capturing vector data and/or for extracting only attribute data showed that 92% of the photographs are potentially useful for updating the content of the 1:5000 scale topographic map.

  • Jesenko, D., Mongus, D., Lešnik, U. (2022). The Influence of COVID-19 on particulate matter concentrations in a medium-sized town. Promet, 34 (5), pp. 813-823, DOI: https://doi.org/7307/ptt.v34i5.4121. [COBISS.SI-ID 126016771]

The pandemic caused by the coronavirus COVID-19 is having a worldwide impact that affects health, economy and air pollution in cities indirectly. In Slovenia, as well as in all other countries, the number of cases of infected people increased continually in 2020, which affected the health system and caused movement restrictions, which, in turn, affected the air pollution in the country. This article presents the indirect effect produced by this pandemic on air pollution in Maribor, Slovenia. Traffic and air quality data were used to perform the evaluation, in particular PM10 and PM2.5 daily concentrations from the monitoring station in Maribor. By observing the detailed traffic data and particulate matter concentrations acquired in the Maribor city centre before and during the pandemic times, we show the influence of COVID-19 on particulate matter concentrations in that part of the town. The results show slightly lower particulate matter concentrations, which could be explained by the significantly lower traffic volume values in the lockdown months.

This article presents the characteristics of smartphone images and their potential for collecting the volunteered geographic information. Today the smartphone image quality is equivalent to those taken with compact digital cameras, and they allow the real-time storage of the location from where the image was taken. Taking the example of processing a single image by using interactive orientation, these advantages are evaluated in terms of their potential for photogrammetric measurements when updating topographic maps. Despite the promising potential, the field of view extent of an image ultimately determines whether we will be able to extract metric spatial 3D data from such an image.

  • Jesenko, D., Mongus, D., Lešnik, U. (2021). Influence of COVID-19 On PM10 Concentrations in Maribor. In: Letnik, T. (edt.). 19th European Transport Congress of the EPTS Foundation e.V : European green deal challenges and solutions for mobility and logistics in cities : conference proceedings : October 7-8, 2021, Maribor, Slovenia. 1st ed. Maribor: Zum urbanizem, planiranje, projektiranje: University, 2021, 173-182, https://www.fgpa.um.si/wp-content/uploads/2021/12/Conference-Proceedings.pdf. [COBISS.SI-ID 91893507]

The pandemic caused by the coronavirus COVID-19 is having a worldwide impact that affects health, the economy and affects the air pollution in cities indirectly. In Slovenia, as well as in all other countries, the number of cases increased continually in 2020, which has affected the health system and caused movement restrictions, which, in turn, affects the air pollution in the country. This article analyses the indirect effect produced by this pandemic on air pollution in Maribor, Slovenia, by comparison of data from a period of movement restriction of the citizens by the government – the COVID lockdown periods in 2020 with data from baseline conditions, starting in 2013. Traffic and air quality data, in particular PM10 daily concentrations from the monitoring station in Maribor, were used to perform this evaluation. By processing, observing, and analysing detailed traffic data and PM10 concentrations acquired in the Maribor (Slovenia) city centre before and during pandemic times, we show the influence of COVID-19 on PM10 concentrations in that part of the town. Results show slightly lower PM10 concentrations and significantly lower traffic volume values in lockdown months.

Building footprint detection based on orthophotos can be used to update the building cadastre. In recent years deep learning methods using convolutional neural networks have been increasingly used around the world. We present an example of automatic building classification using our datasets made of colour near-infrared orthophotos (NIR-R-G) and colour orthophotos (R-G-B). Building detection using pretrained weights from two large scale datasets Microsoft Common Objects in Context (MS COCO) and ImageNet was performed and tested. We applied the Mask Region Convolutional Neural Network (Mask R-CNN) to detect the building footprints. The purpose of our research is to identify the applicability of pre-trained neural networks on the data of another colour space to build a classification model without re-learning.

Different possibilities of collecting volunteered geographical information also in geodesy enable the engagement of volunteers for different purposes. In this paper, the study on the willingness of volunteers to report changes on topographic maps based on online survey is presented. This online survey was answered by 653 Slovenian respondents who use various online or classic topographic maps in their free time or at work and would mostly be willing to report their knowledge of changes in space or map errors to the map updating institution. The main finding of the survey is that 56% of respondents would use any kind of online application to report changes on maps, and surprisingly still 38% of respondents would prefer to report changes via email, and only 4% of respondents would prefer to report changes by phone. We also analysed the potential use of different functionalities of the web application for collecting changes and found that the most important functionalities for volunteers are those that give the most in-depth feedback (that a contribution has been submitted, that it is being verified, that it has been taken into account, that it has been deleted). The willingness of potential volunteers for frequent use of various proposed functionalities also depends on their current engagement on social networking sites or in volunteer associations and on the age group to which they belong.

  • Triglav Čekada, M. (2021): Glacier mass balance calculation in the time of freely available satellite data. In: Kuhar, M. (ur.), Pavlovčič Prešeren, P. (ur.), Vreča, P. (ur.). Raziskave s področja geodezije in geofizike 2020 : zbornik del : 26. srečanje Slovenskega združenja za geodezijo in geofiziko, Ljubljana, 28. januar 2021. Ljubljana: Slovensko združenje za geodezijo in geofiziko, str. 21-35, http://fgg-web.fgg.uni-lj.si/sugg/referati/2021/SZGG_Zbornik_2021_E_publikacija.pdf [COBISS.SI-ID 55923971]

Medium-resolution, freely available satellite data, such as Sentinel-2, Landsat-8 and Sentinel-1, allow the automatic identification of glacier surfaces in multispectral spectra and radar intensities. By adding a digital terrain model to the satellite imagery and assuming a uniform density for the whole area of the glacier, the mass balance of the glacier can be calculated based just on the changes in the glacier surface area. Not only from the glacier area, but also based on the known altitude where the snowline is located at the end of the melting season, which can be measured from multispectral or radar satellite data, the mass balance can be calculated as well. The examples of very small glaciers, namely the Triglav glacier and the Skuta glacier, the large valley glacier the Pastirze glacier in Austria, and the largest of them all, the Vatnajökull glacier in Iceland, are used to describe what we need to be aware of when processing freely available satellite imagery in the study of glaciers.

  • Mangafić, A., Žagar, T. (2020): Creation of high-resolution synthetic orthophoto based on Sentinel-2 imagery using super-resolution generative adversary networks. In: CIGLIČ, Rok (ed.), et al. Modeliranje pokrajine, (GIS v Sloveniji, ISSN 1855-4954, 15). 1. izd. Ljubljana: Založba ZRC. str. 97-105, DOI: 10.3986/9789610504696_07. [COBISS.SI-ID 28636931]

In this paper, we present a deep learning approach to produce high resolution, 2.5 meter synthetic orthophoto from Sentinel-2 imagery. The enhancement method is based on generative adversarial networks, which are a class of deep learning systems based on two neural networks, a generator and a discriminator. We used super-resolution generative adversary networks (SR-GAN) to increase the resolution of selected imagery by executing a sub-pixel prediction. The generator, which we named SRĐAN, is suitable for enhancing all the cloud-free and snow-free Sentinel-2 images that cover North-East Slovenia.

Volunteered geographic information and crowdsourcing are two terms, which describe the use of information with a geographic description, provided by unorganized volunteers through various online tools. In the case of floods and earthquakes, a ten-year international practice of volunteered geographic information usage is presented. Various possibilities of such cooperation are shown: a) when such data are considered by professional researchers only as an input source, b) when they are used for voluntary mapping and c) when trained volunteers are treated as sensors and analysts. Despite the significant increase in the number of volunteers during this time, open issues of such data usage remain the same: how to animate enough volunteers to get the correct display of a natural disaster, how to exclude incorrect data, how to take into account the authorship of the data, and how to prevent the exclusion of those volunteers, which do not have access to the internet at the time of the accident.

In the years 2019–2022 we are conducting an applied research project L2-1826. The main intention of this project is to study how to acquire additional cartographic data for the national topographic map updating in the scales 1:5,000 and 1:50,000 with the help of volunteered geographic information (VGI) data gathering, especially volunteered images. An interactive orientation (monoplotting) enables acquisition of 3D-data from singe volunteered image by the help of dense digital elevation model. Based on our previous experience when we used singe volunteered images for the 2012 flood delineation, this project has the following main intentions: i) asses what kind of data, which can be useful for map updating in the scales 1:5,000 and 1:50,000, can be derived from volunteered images, ii) optimise the interactive orientation method (monoplotting) to enable a quick orientation of arbitrary single images obtained from volunteers by means of different dense digital elevation models or dense point clouds (in Slovenia we have free available aerial lidar data), iii) Perform a controlled VGI collection and processing, with a stress on volunteered images. Controlled VGI collection will enable analysis of the role of different cognitive strategies applied by the involved volunteers to better plan the future open VGI collection campaigns, analysis of the role of involved experts and non-experts in providing adequate images for topographic map updating, etc.

Most important socio-economic results of the project group

  • Počkaj, C. D., Triglav Čekada, M., Petrovič, D. (2022). Evaluation of OpenStreetMap, Wikimapia and OpenTopoMap data quality for test sites in Slovenia. V: LAPAINE, Miljenko (ur.). Program and abstracts : 18th International Conference on Geoinformation and Cartography, 14–16 September 2022, Selce. Zagreb: Hrvatsko kartografsko društvo, Str. 31. ISBN 978-953-49711-1-6. [COBISS.SI-ID 126717187]

OpenStreetMap, Wikimapia and OpenTopoMap are three online cartographic platforms that are formed based on Volunteered Geographic Information (VGI). In our analysis we focused on completeness and positional accuracy of the displayed data. Three types of test areas were chosen within Slovenia%s boundaries, representing urban, rural and high mountain areas and for each type three test sites were determined. As a reference data latest ortophoto and lidar data, supplemented with vector topographic database data, building cadastre, cadastre of public infrastructure and eVode (eWaters) were used. The focus was on three object groups: buildings, transport networks (roads and paths) and water (rivers and streams). The results show that the quality of the data differs between the different cartography platforms and also the different types of test areas.

Triglav Čekada (GI) was in 2022 a co-supervisor for diploma thesis, which dealt with the issue of completeness of data displayed on the OpenStreetMap, the Wikimapia and the OpenTopoMap for test areas in Slovenia.

  • Triglav Čekada has been a member of scientific and editorial board of 16. biennial symposium GIS in Slovenia: “ Preteklost in prihodnost ”, which was held live on 29. 9. 2022 (https://giss.zrc-sazu.si/ODBOR).

Breg Valjavec et al. (editors) (2022). Preteklost in prihodnost (GIS v Sloveniji, 16). Založba ZRC, DOI: https://doi.org/10.3986/9789610506683.

The results of the project are presented in the EuroSDR publication, which promotes knowledge transfer between research and educational institutions and European surveying and/or mapping administrations.

  • Triglav Čekada has been a member of organising board of 26. srečanja Slovenskega združenja za geodezijo in geofiziko, which was held live on 28 January 2021 in Ljubljani. At the same time a proceedings of the event was published:

Kuhar, M. (urednik), Pavlovčič Prešeren, P. (urednik), Vreča, P. (urednik) (2021): Raziskave s področja geodezije in geofizike 2020: proceedings: 26. srečanje Slovenskega združenja za geodezijo in geofiziko, Ljubljana, 28. januar 2021. Ljubljana: Slovensko združenje za geodezijo in geofiziko, 1 spletni vir (1 datoteka PDF (124 str.)), ISBN 978-961-95299-0-4, http://fgg-web.fgg.uni-lj.si/sugg/referati/2021/SZGG_Zbornik_2021_E_publikacija.pdf [COBISS.SI-ID 53030659]

  • Triglav Čekada has been a member of scientific and editorial board of 15. biennial symposium GIS in Slovenia: “Modeliranje pokrajine”, which was held live on 30. 9. 2020. At the same time a monograph of the event was printed and is freely available in e-form:

Ciglič, R. Geršič, M., Perko, D., Zorn, M. editors (2020). Modeliranje pokrajine, (GIS v Sloveniji, 15). Založba ZRC, 200 p., ISBN 978-961-05-0112-1.1, [COBISS.SI-ID 296251648], https://zalozba.zrc-sazu.si/p/1530

  • Triglav Čekada has been a Chair of the Program Committee for the Slovenian Surveying Day 2020, which was postponed from 13. 3. 2020 to 17. 9. 2020 due to the coronavirus crisis. It was held in hibrid way (partly live and partly web conference) on 17. 9. 2020.

Triglav Čekada, M. (editor). Geodezija za kakovostne odločitve v prostoru in času = Geodesy and quality of geospatial data for good decision-making: povzetki predavanj. Ljubljana: Zveza geodetov Slovenije: Ljubljansko geodetsko društvo, 2020. ISBN 978-961-93656-5-6 [COBISS.SI-ID 304269568]