A photo, Google Earth and satellite images: this is how they managed to geolocate a lost hiker
René Compean, a 45-year-old hiker, recently got lost in the Los Angeles National Forest, California. The last that was heard of him was a photograph you sent to a friend of yours from a top. You could see his feet and part of the relief under him. It was enough for an amateur satellite imagery to find its location.
Around 3:45 p.m. last Tuesday, a rescue team found René Compean. Scouring the entire forest for the hiker would have taken days and probably wouldn’t have survived that long. Instead, the rescue team went directly to a location suggested to them by a hobbyist. It was just over a kilometer from that location.
Much of the success of this rescue mission is due to Ben Kuo, an avid hiker who is also fond of satellite imagery. When the Los Angeles authorities decided to publish the photograph that René Compean sent to his friend, Ben Kuo was one of those who tried to offer ideas of where the lost hiker might be found.
As it did? On your Twitter account has explained it Recently. As he explains, the first thing he did was identify the area of the forest where the hiker had gone. It was Mount Waterman, a popular spot for hikers. From there he had to identify whether he had gone north or south.
To get this was based on the vegetation in the photograph. The problem is that if we go to Google Earth for example (which just a few hours ago has added cool features) The images it shows are archival and not recent. Instead Ben Kuo turned to the images of the Sentinel-2 of the European Union, a satellite that collects photographs of the Earth updated every several days. We recently saw how picked up the great snowfall of Spain.
Google Earth has archived data, so it’s tough to use the photo of the legs for any idea of where the photo was taken. Sentinel-2, on the other hand, shows where the vegetation roughly matches the background of the legs (green in the bottom but burnt/dry above). 6/x pic.twitter.com/9F2sSAzRvK
– AI6YR (@ ai6yrham) April 14, 2021
This is how Ben Kuo was able to observe an area on Mount Waterman that resembled the one in the photo due to the amount of vegetation that there was and the shapes that it had. Now the angle was different so he couldn’t be sure. However, the visualization tool in Sentinel-2 allows you to view the images in 3D, allowing you to cchange the perspective and see if one of the angles coincided with the one in the photograph of the hiker.
Everything seemed to indicate that yes, it was that place. To be sure of it Ben Kuo finally He checked one more piece of information: the time of the photograph and the shadows caused by the Sun at that moment. With Google Earth and its time tool it is possible to see how the shadows of a relief change throughout the days and hours, depending on the position of the Sun. And … yes, the place did indeed coincide with the one in the photograph.
We are so grateful for a happy ending to this search. A huge TY to @AltadenaMRT @SierraMadreSAR Antelope Valley SAR, @SCVSHERIFF SAR, and @SEBLASD Air-5. We further want to thank the online community and especially @ ai6yrham. His clue greatly helped us find the hiker.#LASD pic.twitter.com/Ope322D0Z2
— Montrose Search & Rescue Team (Ca.) (@MontroseSAR) April 14, 2021
Via | @ ai6yrham