Mdina Archives 3D Cistern Visualization

On Wednesday (3/16/11), we went to Mdina to explore another cistern at The Archives of the Cathedral of Malta. This cistern was especially interesting because of its shape. The cistern consisted of a shaft down the center and two bell-shaped cisterns branching off. The smaller cistern's access point was at about 16 meters underwater down the shaft, while the larger cistern's access point was at about 22 meters down the shaft. Gathering enough sonar data for this cistern was very difficult due to the complexity of two cisterns in one. It was difficult to navigate between cisterns through the shaft while keeping track of the distance moved and the orientation of the ROV. We collected 50 sonar scans in all where 15 of them where side-scans. (The sonar was rotated sideways to collect vertical data of the cisterns).

Over the past few days, Chris and I have been analyzing this data and creating sonar mosaics (the compilation of multiple sonar scans to create a map) in order to create a 3D map of the entire cistern. So far, we have created a 3D map and now I am handing it off to Christina for her to transform it into a pretty 3D visualization. The image below represents a map of the entire cistern, which includes both of the sub-cisterns. (This is before Christina's visualizations). You can see the smaller cistern on the left that branches out from the shaft and the larger cistern is on the right. This map was generated with the sonar data using the sonar mosaics to calculate the ROV position at each of the scans and also SLAM (Simultaneous Localization and Mapping) to help better align the individual scans.

Chris's Day

This Saturday was Chris's last day in Malta before he left to rejoin his family in San Luis Obispo. Chris really wanted to visit a place on Malta that he had not been before during this, and his previous visits. So, looking through our guidebook, he stumbled upon Golden Bay.

Golden Bay is a small inlet with a sandy beach, small waves, and a great place to go snorkeling. Despite the looming clouds, snorkeling took place by some, while half of us, me included, decided to lay out on the beach enjoying the sunshine while it was still around. Zoe and Tyler dug a big hole - which Tyler decided to sit in. Later, Tyler and Andy went exploring - ending up on the top of large overhanging cliff to the right of the beach, while Joe, Zoe, and I fell asleep, napping in the sun.

After the snorkelers got back, we all went on a short hike up to the top of the overhanging cliff on the left side of the beach where an old abandoned watch tower stood. We then hiked up the hill further to some more abandoned buildings.

After watching the clock closely we headed back down to the bus stop to catch the last bus out of the area at 5:05 pm - and as usual, it was Mr. Toad's wild ride the whole 30 minute ride back to Sliema.

Everyone was happy and tired getting back to the apartment - a very needed restful day, full of exploring and good times.

Inspiring the Next Generation - Teaching Robotics

Part of the ICEX goals this year have been reaching out to elementary school aged children and introducing them to robotics and inspiring them to go into science and technology fields. During the quarter back at Cal Poly, we visited two different 2^nd grade classrooms at Pacheco elementary school every Wednesday. We switched off between the classrooms and had hands-on lessons that talked about design, testing and programming. It was very successful. The kids seemed to really enjoy it and retain a lot of what we taught. We even got a book of thank you notes written by all the students afterward – a nice touch.

Originally, that was going to be the extent of our outreach. At the suggestion of Timmy though, we packed a suitcase full of little robots so we could continue the lessons at several Maltese grade schools. We started off with a brief lecture about different types of robots and introduced the robots we brought and the paper disks used to program them.

The disks we used were small circular pieces of paper (that we had to individually cut out beforehand). The robots have two sensors that read the disk as it rotates and determines if the 2 rows of squares are black or white. Depending on the combination of black and white, the robot will go forward, stop, or turn left or right.

We then broke the students into groups of 3-4 and let them each “program” the robot to navigate a simple maze we created on the floor with tape by coloring disks with black pencils and pens. Overall, the students were very excited about it and there were several students who even inquired about where they could get their own robot so they could do more on their own.

It was encouraging to be so enthusiastically received by both the students and faculty of the schools and in addition to being a good educational experience for the students there, it was a great experience for the ICEX team as well to be able to talk with so many students (who represented a variety of ethnic backgrounds).

The Cave

Today (Wednesday) we began exploring a cave at St. George's Bay in St. Julian's. It was huge! It is this large, deep pool of water contained completely in this cave. We had a bit of a trek to get to the entrance, and when we got there, we had to walk down a staircase which led to the water. We set up our equipment up near the entrance so we had some light to work in, and Andy and Brig practiced their driving skills for the first time since we've been here in Malta.

Unfortunately, like yesterday, we had a lot of technical problems with the sonar communication (a relatively new problem since Chris showed up...impeccable timing). We ended up deciding to not dedicate too much time initially to troubleshooting the problem, and get on with exploring the cave. We took a lot of video and really just wanted to get a feel for the size and environment of the cave. With 3 days to explore, we wanted the first day to be dedicated to getting a grasp on the cave as a whole.

Around lunchtime, we decided to pull the ROV out, and attempt to do some debugging on the sonar connection. We narrowed the problem down to the actual connection between the ROV and the tether, but were not able to come up with a solution on site.

Deciding to continue with just video, we put the ROV back in the water and I took control of the control box for awhile. My goal was to get as deep into the cave as possible, given the limited amount of cable we had.

After exploring for awhile, I hit a maximum depth of about 35 meters (114 feet!). I went into the cave as far as I could, and when I was pretty sure I had run out of cable, we decided to turn around. Upon trying to surface, I realized that there was a bit of a problem: I had created some significant snags in the tether while driving around. This was probably one of the worst tangles that the ROV had experienced thus far, according Chris, so as one could guess, there was a bit of stress around the cave site. Half of the team was down in the cave, waiting to wrap up the cable as it became untangled, while the other half watched the video feed and attempted to strategize a plan to untangle the ROV. Chris ran back and forth between the computer and the cave to try and quickly solve the problem so we didn't end up becoming completely stuck in this massive cave. It took quite awhile to remedy, but after some careful driving, we were free and to the surface. Getting stuck allowed us to more closely see some of the natural formations of the lower parts of the cave, which were super interesting!

With the significant technical problems of today, we have decided that it would be best to stay home and troubleshoot tomorrow instead of trying to explore the cave with non-functioning equipment. We hope that by Friday, we will be able to have the sonar connected so we can create some maps of the cave (not an easy task), and maybe even connect our second tether so we can explore even deeper!

More pictures from the pool

Sorry for the delay, but here are the pictures I took from the day at the pool