Positive crop marks of a circle ditch in soybean

The starting point for this aerial survey at the end of July 2015 was the previous discovery of a previously unknown circular trench on satellite images that could be viewed on the internet via Bing Maps. At the time of the flight, the field was cultivated with soybean plants. The circle ditch stood out in the oblique image against the low morning sun as crop marks due to different height growth and differences in leaf colour.

The vertical image, on the other hand, only shows the slight differences between the richer colours of the plants on the trench and the paler colours of the neighbouring plants. It does not achieve the expressiveness of the plastic oblique image.