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Mapping cemeteries by UAV in Czech Republic

Jakub Karas
UAS manager

A Czech Republic-based company uses unmanned aerial vehicles to map the cemetries in the country to maintain an up-to-date database of all the graves.

Traditionally, military have been using Unmanned Aerial Vehicles (UAVs) for intelligence gathering. But now, UAVs are being used in mapping and surveying for various other purposes. A Czech Republic-based UAS company UPVISION in cooperation with Brno City Hall (the second largest city Czech Republic), explored the possibilities of using a UAV to map the cemeteries in the country. After mapping the cemeteries the data, was integrated into a GIS system. This up-to-date database proved extremely beneficial to the administrators in managing public cemeteries and hundreds of associated permits.

Brno at 1cm/pixel resolution

UAVs to the rescue
Unmanned aerial vehicles (UAVs) were used to create high resolution orthophotos and subsequent vectorisation of the graves and the possibility of adding raster layer (orthophoto) to the database system.

The actual mapping was conducted after the spring season to prevent trees from blocking the graves and the stabilisation control points (known points, corners paths) was conducted by a hexacopter.

Each cemetery was mapped in a single flight by the UAV. For mapping smaller cemeteries, Hexacopter with flight plan, image resolution 1 cm/pixel, overlaps 80/60 was used. The mapping was done in just 10 minutes.

For mapping bigger cemeteries like the Central Brno cemetery, which has over 80,000 graves, UAV with a flight plan with a copy of the terrain was used, because this cemetery is in the gradient terrain, where elevation differences was about 60 meters. Image resolution was 2 cm/pixel and overlaps 85/65. This biggest flight plan was 40 minutes flight time, with manual landing nearby. There were more than 3000 images, with external orientation and post processing process to build the orthophoto map and digital surface model was around two days. As a result orthophotos with an image resolution of 1 cm/pixel, in the Czech coordinate system, were developed. They were used as a basis for semi-automatic vectorisation of graves.

Image of graves captured by UAV

At the same time, oblique aerial images of the graves from UAV were made which identified the number of graves and descriptions, which will serve to further populate the overall database of the entire cemetery to identify each grave and provide a simple registration process for the administrator and the city.

A big online database system with graphic layers including; high resolution orthophoto maps, vector layers etc was developed. The database is useful for administrators of the cemeteries to keep a tab on the registration of the graves. Only one mouseclick on the representation of a tombstone on the map is necessary to retrieve the detailed information about one permit. The relatives of the deceased can also see the grave number, name and photo of their loved ones.