Caption
The image shows a bird’s eye view of one of the galleries of the Grotte de la Madeleine cave, located in the heart of the Gorges de l’Ardèche in southern France. This was entirely scanned using ground-based lidar, also known as 3D laser scanning, which makes it possible to “see” from the outside and thus identify features formed in the past. This technology provides an unprecedented overhead view (or nadir view) of the ceiling of the gallery and its astonishing formations, testifying to the erosion that created these imposing shapes several million years ago. This technique provides very high-resolution 3D-images of sections of such cavities, although it cannot be used to uncover new ones. The very detailed maps produced in this way enable scientists to explore underground environments that can sometimes be impossible to access. This image is a winner of the 2021 La preuve par l'image (LPPI) competition.
