Effective conservation work to protect native birds is based on an accurate understanding of their status and distribution. One of Austria’s largest heron populations can be found directly on the German border near Reichersberg am Inn. The herons nest in treetops at a remote nature reserve between March and July. Observing and counting the birds can prove challenging for ornithologists as many of the birds and nests are hidden amongst the treetops and can be difficult to see from the air or from the ground.

Drone Field Tests
During the early morning hours of July 11, 2019, members from the JKU Institute of Computer Graphics conducted a field experiment in cooperation with conservationists Karl Billinger and Christian Doms to test a new drone camera and use the "Airborne Optical Sectioning (AOS)" measuring technique developed at the JKU. The drone was 1.2 meters in diameter and equipped with a high-resolution color camera as well as a thermal imaging camera. In order not to disturb the birds, the drone was launched at a distance of 350 meters and after seven minutes of flight time, the drone conducted a complete and autonomous scan of the nesting area from a height of approximately ten to fifteen meters above the tree tops. The captured image material was mathematically combined with the total optical signal corresponding to a synthetic lens 40x12 meters in size. This signal allows the forest to be "virtually dissected" from the ground up to the tree tops and scientists were able to identify and count the birds and nests as well as determine their three-dimensional position.

Broad Range of Applications
The AOS measuring technique can be used for a wide range of applications that include border control purposes, archaeology, forestry, and agriculture. Scientists will continue improving and testing the method as part of a project funded by the Austrian Science Fund and the state of Upper Austria. The technique is not just for observing animals but can also be used for agricultural monitoring as the technology can penetrate dense forests and vegetation to detect hidden objects that cannot be seen using a regular camera. Preparations are currently underway to conduct the next field experiment to observe the peach harvest in Upper Austria.