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Setting standards for cemetery spatial databases – a case
study in the Roman Catholic Archdiocese of Eger, Hungary
Márton Pál a,b,*, Edina Hajdú b
a ELTE Eötvös Loránd University, Doctoral School of Earth Sciences, pal.marton@inf.elte.hu
b ELTE Eötvös Loránd University, Institute of Cartography and Geoinformatics, hajdu.edina@inf.elte.hu
* Corresponding author
Keywords: cemetery mapping, computer vision, GIS, spatial database
Abstract:
Cemeteries have usually been the subjects of culture and various science branches from all over the world: they served
as sample areas for projects in geology, archaeology, anthropology, epidemiology and pathology, as well as some topics
for cartography and GIS (Veit et al. 2009; Sayer et al. 2013, Rasam et al. 2013). In Hungary, there have been initial
steps for applying GIS tools in modern (not historic or prehistoric) cemetery research works: the basic outlines of a
cemetery GIS system were established (Harkányiné Székely 2004). The aim of this project is to provide a UAV-based,
open-source mapping method that is suitable for generating raster maps and editing spatial databases too. We have
delineated three sample areas in Heves County, Hungary: Istenmezeje, Váraszó and Hevesaranyos.
The mission in Istenmezeje took place in the middle of March in cold and cloudy weather, in Hevesaranyos in May (in
moderately warm and cloudy conditions), and in Váraszó in July (in hot and sunny weather). In Istenmezeje, a DJI
Matrice 210 V2 RTK UAV was used (equipped with a DJI Zenmuse X5S sensor), while the Váraszó and the
Hevesaranyos area were flown using a DJI Phantom 4 Pro+. The cause of some differences was the not identical light
conditions. The mission was planned and executed using DJI Pilot software, while the other two missions were planned
and performed using the Pix4D Capture software. A 2D orthomosaic was prepared in the case of all three areas using
the open-source OpenDroneMap software and its WebODM platform (Fig. 1). A Digital Elevation Model (DEM) was
also generated for acquiring contour lines (using QGIS 3.14).
Figure 1. The WebODM platform containing the orthomosaic generated for the cemetery of Váraszó
The delineation of graves was executed in a Python-based environment created in PyCharm. As custom libraries are
easily installable in Python (and they are well-equipped for GIS purposes too), OpenCV and GDAL/OGR functions can
also be applied. A peculiarity of OpenCV is the default BGR colour format. Because of this, in the first step, we needed
to convert our images to RGB first. After that, we converted it to grayscale. After the application of noise filtering, the
grayscale image underwent a Canny edge detection. The resulting file was used for the delineation of the contour lines
of the most important objects. If we set all parameters correctly in the workflow, and the bounding rectangle results are
satisfying, we can save the processed images as GeoTIFFs using GDAL. After defining the file format and the
projection, we get the band that contains the rectangles and write it out as an array. As this image contains the relevant
information as pixel values, it can be converted to a vector file format using GDAL/OGR. Data collection of the buried
Abstracts of the International Cartographic Association, 6, 195, 2023.
31st International Cartographic Conference (ICC 2023), 13–18 August 2023, Cape Town, South Africa.
https://doi.org/10.5194/ica-abs-6-195-2023 | © Author(s) 2023. CC BY 4.0 License.
people could not be done without manual work. A photo was taken from each grave to note down the people’s names
buried in them. We marked each grave on the printed orthomosaic. The personal data noted from each grave were
paired with the polygons vectorised from the orthomosaics. Besides the names, the dates of birth and death were also
included in the database for each person. This was important due to cadastral purposes. Sometimes it was difficult to
determine the exact data from the graves. Most of them were in good condition, but some of them were unreadable.
Cemetery maps were compiled using the determined vectorised polygon set of the graves. It was completed with
contour lines and field elements like roads, pathways, fences, buildings, and other objects. The cemeteries have been
sliced up into parcels. Two types of maps were edited: an overview map showing the whole cemetery, and one
individual map for each distinct parcel (Fig. 2). The purpose of the database is to continuously monitor the changes in
the cemeteries. This means the recording of new graves and the new people buried in existing graves (this is needed due
to public health regulations). The database contains the following information: 1) grave ID number, 2) parcel number of
the grave, 3) the names plus birth and death dates of people buried in the grave. New records can be easily added later.
Figure 2. An excerpt of the map of the first parcel in the Istenmezeje cemetery
This new, complex workflow of mapping sets initial standards for the new legal environment of cemetery management
in Hungary. The most important advantages are: 1) the UAV mapping makes data acquisiton on this large-scale much
easier and less time-consuming, 2) the automated vectorisation workflow can also reduce working hours of mapping, 3)
pairing the manually edited photo-based database with the map makes it easier to produce consistent data and adding
new records is not difficult. Although this methodology can effectively contribute to the large-scale mapping of
cemeteries, there are some disadvantages too that can be originated from the workflow steps. 1) The legal background
of UAV missions is difficult and requires thorough attention, 2) the execution of drone tasks requires practice, while the
image processing and data storing is a question of IT capabilities, 3) the free installation of the WebODM platform is
difficult for people with no IT background, 4) correct mapping also requires some background knowledge (despite the
resulting maps are not very complex and do not contain lots of information).
Acknowledgement
MP was supported by project no. TKP2021-NVA-29, which has been implemented with the support provided by the
Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund,
financed under the TKP2021-NVA funding scheme.
References
Abdul Rasam, A.R., Mazlan, A.S. & Wan Rodi, W.N. (2013): GIS-based muslim cemetery information system. In:
2013 IEEE business engineering and industrial applications colloquium (BEIAC). Langkawi, pp. 364–368. DOI:
10.1109/beiac.2013.6560149.
Harkányiné Székely, Z. (2004). Temetői térinformatika. Acta Agraria Kaposváriensis, 8(3), 91–97.
Sayer, D., & Wienhold, M. (2013): A GIS-Investigation of Four Early Anglo-Saxon Cemeteries: Ripley’s K-function
Analysis of Spatial Groupings Amongst Graves. Social Science Computer Review, 31(1), 71–89. DOI:
10.1177/0894439312453276
Veit, R.F., Baugher, S.B. & Scharfenberger, G.P. (2009): Historical Archaeology of Religious Sites and Cemeteries.
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Abstracts of the International Cartographic Association, 6, 195, 2023.
31st International Cartographic Conference (ICC 2023), 13–18 August 2023, Cape Town, South Africa.
https://doi.org/10.5194/ica-abs-6-195-2023 | © Author(s) 2023. CC BY 4.0 License.
