You've probably seen them:ghostly underwater images of the wreck of the Titanic at the bottom of the Atlantic Ocean. They were already nice, but better material is on the way. A large expedition is working to visualize the sunken ship completely in 3D.
It has been nearly 100 years since the Titanic sank to the bottom of the Atlantic Ocean. On April 10, 1912, the ship departed from Southampton harbor to make the crossing to New York. As we know, it never got there:the Titanic sank early in the morning on April 15 after ramming a heavy iceberg.
The wreckage was recovered in 1985 and since then many expeditions have been conducted to investigate the Titanic. It is now known that there are three large ship parts on the bottom:the bow, the middle part of about 20 meters and the stern. That last part is badly damaged, but the bow is reasonably intact. You could still see the chandeliers hanging in the large halls.
And soon you will be able to see it with your own eyes, completely in 3D. Since August 23, a large expedition has been investigating the ship again, but this time with the most advanced techniques.
Two ladies exploring
The Titanic is under investigation by two AUVs and one ROV. An AUV is an Autonomous Underwater Vehicle , a kind of small submarine that goes exploring on its own. There is no crew on board and it is not controlled remotely. That is the case with an ROV, a Remotely Operated Vehicle . It is also unmanned, but the control is via a long cable from the mothership.
The AUVs, called Mary Ann and Ginger, map the area around the wreck with the side-scan sonar -Technic. Each AUV emits sound waves on both sides, which then bounce off the bottom and the wreckage. Using the returning sound waves, the AUV can then calculate the distances between itself and the obstacles. You can then visualize those distances (see below), so that you get a good idea of the area.
The sound waves reach about 600 meters on each side. To cover the entire area, the two ladies therefore sail back and forth, like a kind of lawnmower. They sail the same part, but in different directions:Ginger sails from North to South, Mary Ann from East to West. This is because acoustic shadows are created, like the black spot you see in the image above. Those are areas that the sound waves don't reach because something is in front of them (the bow in this case). By having the other AUV come in from the other side, the shadows can be filled in later.
Quick details
The side scan image may not look that special, but it is. The area has never been mapped before and important discoveries are still possible. Not all parts of the Titanic have been found and it is not known exactly where the wreckage may lie. In addition, it is very special that this card was made so quickly. Within 24 hours of the launch of the AUVs, a detailed overview is displayed on the screen; that is the first time in an underwater survey.
The speed is due to the high-tech version of the AUVs. Because they have their equipment on board (and not drag it behind them), they can maneuver easily. The super-accurate navigation also ensures that they quickly find interesting places. This is important because the two AUVs are on the road several times. The first time they map the area globally, then they go back for more detailed images.
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There, for example, they use the multi-beam option from Mary Ann for. That's a sonar looking down with a lot more pings (back and forth sound waves) per second. As a result, the resolution of the sonar images is higher and a 3D map of the bottom can be made from this data. However, the range of the multi-beam is smaller than with the side scan sonar (see image below). That's why the researchers only use the multi-beam on the second scouting trip, when they know exactly where to look.
Watch Live 3D
In addition to the sonor images, 3D video material is also made and that is what the ROV is for. The Remora 6000 is equipped with 5 HD cameras, which can record up to 6000 meters depth. The data from the AUVs comes in handy, because with the detailed map, the ROV pilots can navigate past all the wreckage better than ever. The filming itself is not very different from shooting a movie in 3D, except that it is done at a depth of about 3700 meters and the crew can view the recordings in real time. They all sit with glasses on and look at the screens, on which they see live what the ROV 'sees'.
But that is not everything. The ROV also has sonar imaging heads on-board. These are a kind of cameras, but with sonar. The ROV turns on the devices at 20 to 30 points around the Titanic and then makes them 'look' in three directions. Like regular sonar systems, they emit sound waves and wait for the reflection. Only they do not produce a circular image with a few dots, but a photo-like image (see below).
By taking such sonar images at multiple points and in multiple directions, the software can subsequently create a 3D model of the ship. This is very useful, because it makes it much easier to determine distances. The model also enables the researchers to better monitor the deterioration of the wreck. By comparing the current model with old photos and future recordings (whether or not in 3D), they can clearly see how fast the ship is sinking.
Good to follow
Still, the 'regular' 3D images are the most spectacular for most people. That is also important for oceanographers. Underwater videos don't normally get most people hot or cold, but when it's in 3D… The researchers hope this will increase the public's interest in oceanography.
In any case, it will not be the media's fault. In America, the MSNBC station makes a daily report from the research vessel. They have a reporter on board who can follow closely what is happening.
The team maintains an extensive Facebook page and regularly tweets the state of affairs. You will also find a lot of information on their own website (all in English). The researchers want to share their experience with the whole world and let everyone 'enjoy' the greatness of the Titanic. So far they seem to be succeeding. In a few days they managed to make a detailed map, 16,000 photos and spectacular 3D recordings in HD quality.