This weekend, a small ultralight aircraft, which is normally used at the Brno University of Technology for research and training purposes, had a completely different task: to capture an area damaged by Thursday's tornado. The resulting orthophotomaps from Saturday morning use components of the integrated rescue system.

"After an agreement with the rescuers working at the place of the disaster, we went to map the affected area. Due to the size of the area, it was not possible to use our standard drones. That's why we adapted the scanning system for the piloted aircraft within a few hours and photographed the area for the first time on Friday evening. We processed data overnight on Saturday, and since Saturday morning our orthomosaics have been helping rescuers both in the staff and in the field," Petr Dvořák from the Institute of Aerospace Engineering, Faculty of Mechanical Engineering, Brno University of Technology said.

The Institute of Aerospace Engineering has long been integrated into the region's rescue system, so rescuers can contact the pilots at any time if necessary. The two-seater ultralight aircraft, equipped with a synchronized camera and a precise navigation system, took off for the first time on Friday evening, but the quality of the outputs was not ideal due to the lack of light and showers. On Sunday, the second shooting was taken in significantly better conditions. Rescue services also wanted to see the changes that had taken place in the field in the meantime.

The mapping flights lasted approximately two hours each, during which the entire area affected by Thursday's tornado, approximately 100 square kilometres, was mapped. The resulting maps have a resolution of approximately 20 centimetres per pixel (pixel). From the obtained data, various outputs are processed according to the agreement with rescuers, but the most important are the so-called georeferenced orthomosaics, i.e. aerial maps with exact coordinates.

"Rescuers manage the whole operation in an interactive system, where they have different map layers available. The fact that we will supply them with a current orthophotomap of what is damaged is a very valuable input for them. No one else could do it now: traditional imaging planes, which operate at an altitude of several kilometres, need cloudless weather, as do satellites. The area is too large for drone photography. In this case, we fly at an altitude of 850 meters, which on Friday and Sunday was below the cloud bases," Dvořák adds.

The unique dataset is offered free of charge by BUT primarily for rescue and research needs, for further free use for non-commercial purposes it is available here.