GUMBO LA BAHARINI 3D
MODELING OF A KARST CAVE BETWEEN 50 AND 80 METERS DEPTH!
Building on the success of the Gumbo la Baharini mission of 2023 which aimed toextract a stalagmite more than twenty thousand years old at a depth of 75 meters (a world first), the team of the DEEP BLUE EXPLORATION association is back on track the palms for a second, equally unique mission!
Une mission rendue possible grâce a nos partenaires :
The DEEP BLUE EXPLORATION team had 15 days in January 2024 to take the necessary data to make a 3-dimensional modelling of the karst cave located on the edge of the pass to the boat south of the Mayotte lagoon. To do this, a team of 4 tek divers with their closed-circuit recyclers have dived for 12 days between 50 and 80 meters deep in the guts more or less wide in the depth of the lagoon Mahorais.
The passage to boats, south-west of the lagoon of Mayotte where is the karstic cave.
A HUNAINE ADVENTURE
The DEEP BLUE EXPLORATION team is recharging the fins and releasing the closed-circuit recyclers for this new challenge initiated by Gaby!
- 4 tek divers are there: Camille LOISIL, Patrick PLANTARD, Thomas GAUTIER and Gaby BARATHIEU.
- Armand DAYDE Diver, Cameraman and Documentary Director •
- Jérome MATHEY and Delphine from Drone GO
- The women scientists of the DBE association, Dr Isabel URBINA-BARRETO and Héloïse ROUZÉ
By launching this expedition, Gaby BARATHIEU presents her team and himself with a challenge: to create a complete model of an underwater cave of karstic origin, with its architecture and winding path. Composed of several rooms and narrow, collapsed blocks, stalagmites and stalactites (most often fallen to the ground by ancient earthquakes) but also large area with deposits of very volatile sediments.
This fine 3-dimensional modelling will allow scientists to have a global vision and better understanding of their training. Indeed, there are still many questions that remain unanswered, especially on its orientation which seems to point towards the interior of the lagoon.
The chaotic sky throughout the mission. @ Armand DAYDE
The weather did not leave us during the 12 days of the mission. Between rain, wind and poor visibility of the water, the morale of the team held up and the good atmosphere of the group easily took over the bad weather conditions.
Fortunately the water was warm, very hot with 30 degrees on the surface for 25 degrees at the bottom of the gallery at 80 meters depth.
Poor visibility at launch! @Armand DAYDE
Loading equipment onto boats from ABALONE dive club base. @Armand DAYDE
Trimix rebreather divers with a Seacraft DVP. @Armand DAYDE
This ambitious and a little crazy project of modelling a karstic cave in the mesophotic area is above all a human adventure. A team of 10 people including 4 TEK divers equipped with closed-circuit recycler will
Fortunately, once in the cave, conditions become stable, without current and with good visibility a few meters further from the entrance (provided that no sediment is raised while palming).
The opening of the lagoon floor straight towards the karstic universe of this cave dating from the ancient geological era of the Pleistocene. @Gaby BARATHIEU
The entrance to the cave at a depth of 60 metres. @Gaby BARATHIEU
The main gallery is 130 metres long and located on the lagoon floor at a depth of 48 metres. The last room is at about 80 meters deep.
@ Gaby BARATHIEU
We never get tired of the atmosphere in these dark guts even after more than 50 dives. Each immersion is unique and makes us discover new forms, new concretions that had until now escaped the beam of our lamps. The inhaled trimix mixture also strongly influences the diver’s perception. This was particularly noticeable when we opted for a mixture richer in helium (10/70 instead of 10/50)!
Then, thanks to the helium-rich mixture, the vision of certain details appears or is revealed clearly. Certain aspects and texture, the overall shape and volume of some rooms and galleries are better perceived and evaluated.
In the dark gallery of stalagmites! @ Gaby BARATHIEU
Gopros start and 6 lights at 75 meters! @ Gaby BARATHIEU
@ Gaby BARATHIEU
The atmosphere, the mood, the special atmosphere of these karstic environments full of history is one of the main drivers of our explorations and expeditions. The goal of the mission Gumbo La Baharini 3D is to transmit these emotions and this journey in time inside the lagoon floor to as many people. Yet we are only a privileged few with the technical capacity to explore this hostile environment. Less than 10 people have had the privilege of seeing its stalagmites.
@ Gaby BARATHIEU
On the 14 days of missions, we dived 12 days including 2 days or we could not find the entrance to the cave. The required depth times varied between 30 and 60 minutes per dive for a slightly variable decompression time of 150 minutes per day!
In total, for the whole mission we performed 250 minutes of actual work in the cave galleries for a total of 150 minutes of decompression (per diver).
The DBE divers on the way to the decompression pads. Here the first are at a depth of 27 m. @Armand DAYDE
At 6 meters depth we still have one hour of decompression. Impossible to come back to the surface without having very serious health complications.... @Gaby BARATHIEU
The DPV (underwater scooter) are essential tools to perform this type of diving. @Gaby BARATHIEU
The boat in safe surface waiting for the diver’s parachute. @Armand DAYDE
Un défi technique
PHOTOGRAMMETRY
The DPV (underwater scooter) equipped with 12 cameras, 6 lamps and neutral buoyancy system. @Gaby BARATHIEU
Photogrammetry is a technique that involves performing measurements in a scene, using the parallax obtained between images acquired from different points of view. Copying human stereoscopic vision, she has long used it to reconstruct the relief of the scene from this difference in points of view. It is now increasingly using correlation calculations between images that are now digital (digital photogrammetry).
This technique is based entirely on rigorous modeling of the geometry of images and their acquisition in order to reconstruct an exact 3D copy of reality.
For mission needs, Jérome Mathey and Gaby Barathieu have specially designed a system capable of photographing at 360°.
Just over 147,000 photos were taken throughout the main gallery to be able to reconstruct a 3-dimensional model as true as possible. It will take several weeks for the IRD Réunion calculator to reach its goal. This represents more than ten billion operations!
Pré-traitement des données avec le logiciel de photogramétrie METASHAPE.
COVER ALL CORNERS!
One of the main technical difficulties of this mission (in addition to the constraints related to deep diving under ceiling) is to be as efficient as possible in a single pass. To be able to reconstruct the 3-D model, it is necessary to be able to capture information on 360° in order to associate the floor with the ceiling.
THE LIGHTING!!!
In the darkest possible, it is absolutely necessary to have a light strong enough to expose the premises from all angles possible. Special attention must also be paid to the homogeneity of the lighting in order to avoid hot spots such as underexposed areas.
Only the divers' headlights are lit before the photo acquisition phase. @Gaby BARATHIEU
6 lamps of 10 000 lumens each photographed from the front in the darkness of a karst cave at 60 metres depth. @Gaby BARATHIEU
Panorama of 180° at 60 meters depth. @Gaby BARATHIEU
MAKING THE INACCESSIBLE ACCESSIBLE!
Arrived in June, the first complete versions of the cave model are finally generated following billions of calculation made by computers on vitaminé.
Once reserved for an elite diver, the (virtual) visit of this cave is now accessible to all. The primary purpose of the association. DEEP BLUE EXPLORATION and its president is accomplished.
This model also allows an informed view of the whole of this geological structure that can be studied by a scientific team in the near future and will thus allow to better understand its formation.