More Data Processing (i.e. Spring Break on Malta)

So despite this week being our "Spring Break" back home, the majority of hours this week were spent on our computers attempting to organize the massive amounts of data that we've collected during our time here.

One priority was creating a database with Microsoft Access . There wasn't much experience working with the program, but after some tutorials and some figuring, we were able to organize a great deal of our data in one convenient location. Here is a partial screenshot:

This gives easy access to locations, latitudes and longitudes, depths, videos, sonar scans and more. Timmy reviewed it earlier today and was "speechless" which I believe makes the entire trip a success.

But it's not all database stuff. Visualizations need to be created / debugged using the data, pictures and videos need to be sorted, blogs need to be written. and backups of everything need to be made. Not to mentioned prepping our equipment for travel by cleaning and organizing it. We're also creating DVDs for people on Malta that have helped us in our explorations which includes owners and archaeologists. After creating videos, mosaics, compiling data and creating a database, the DVDs will have 1,337 files of our time here. A number to be extra proud of!

So for those that are terribly jealous that our spring break is in beautiful Malta, realize we've been working non-stop! But continue being jealous.

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.

Visualizing the Maltese Archipelago

Over the past few weeks we have been making significant progress on our visualizations of Malta, and finally have a presentable draft of our progress.

Our goal is to create a tool that can be used to educate others about our research which will include a visualization of Malta as well as 3D maps of cisterns with accurate textures and some information from each site. A few of us have been working on creating an accurate representation of the island. We currently have a low quality 3D representation of Malta with bright green pins at cistern locations we have mapped.

Below are some pictures of our progress.

(upper left) The above is a zoomed out picture of Malta and some of the surrounding seabed. There are green pins in some of the cistern locations we have gathered data from.

(upper right) A larger image of the Maltese mainland with a clearer view of some of the places we have visited.

(below) Another zoomed out view with surrounding ocean.

We are currently working on creating a higher quality geometric representation of the island. This will eliminate the blue color seen in the area in between the islands of Malta (the largest and southernmost island) and Gozo (the northernmost island) in the last picture. We are also working on reducing the amount of time it takes to draw the island as there is noticeable lag when moving the camera.

We hope to have a much improved version soon.

The Cave of Wonders

You will wish you were here! Day two of the cave had a few exciting discoveries... as well as a couple of newly created set-backs. Because our sonar was out of commission the first visit, we spent all of Thursday repairing and splicing the tether that caused the problem. Today, we finally had a chance to map the cave and the wonders contained within its depths.

The newly repaired tether worked like a charm as we mapped the surface of the first pool in the cave. We also mapped varying depths at multiple locations in the cave that we hope to "paste" together. This will hopefully be enough data to completely represent the water within the pool in the cave. In addition to horizontal scans with the sonar, we ran a couple of lengths in the pool with the sonar strapped vertically to the ROV. This will provide us with two sets of dimensions to log the depth of the pool. We used this method primarily to make up for our faulty depth sensor in the ROV's control box.

After mapping the pool, I drove the ROV around to get some close up video of the sides and bottom of the pool. I found a lot of interesting things... a couple of tires and oil bins, plenty of rubble, bottles, and occasional sections of wood. One particular piece of wood had a community of water creatures... either miniature crawdads or a type of shrimp. It was pretty cool!

Unfortunately, our repaired cable suddenly failed and we lost driving ability for the robot. We switched to our other tether, but that one didn't connect sonar, so we only did visualizations from then on.

All in all, the cave was very exciting. I only wish I had my scuba gear to dive down in it!

Projective Texturing of Cisterns

For the final presentation of the cistern exploration project, all of the video and images will be mapped to the geometry generated from the sonar data. The screenshot below is a mock world generated to serve as example data extracted from sonar. Using mathematical calculations, the images are loaded into a program and projected onto the geometry (just like you would think a projector to work) to make the world look more realistic and similar to what it actually looked like from the perspective of the robot. There is currently only one projection of one image taken of a cistern a couple of years ago.

At this point, there is certainly more work to be done to merge our actual data and images together. The previous plan was to automate the video frame extraction with the location and orientation of the robot and project it. After completing many projects, we realized that it would be near impossible to complete this automatically and accurately.

Currently, my plan is to (once the geometry is loaded into the program) load images that correspond to the cistern and scan through them until one matches the current orientation within the world. At this point, the image projection will be saved, and a new image can be loaded to project and save to overlay or stitch with previous projections. This method will be an easy way to accurately bring multiple images together and place them in the right place in the geometry to make the world realistic.

Good day!

After a long and hard battle with camera controls in the visualization of our 3D map of Malta, I have finally got them working. My version of Malta is still looking a little orange, but at least I can see how orange it is from all angles.

On another high note, we had the unique privilege of exploring a cave near St. George's bay. This is the one site I was looking forward to the most prior to the trip. I actually had a great conversation about this with a girl on the plane to San Francisco (and in the off-chance that you're actually reading this, Katie, I'd like to get in touch :).

The cave definitely did not disappoint. As we descended into it I was hit both by surprising warmth and overwhelming darkness. My small flashlight did little to illuminate our way and we almost ended up walking straight into the crystalline water because of how hard it was to tell where the dry ground ended. Once we got the ROV in the water and turned on we got a beautiful view of the rocky underwater. There were a lot of technical issues so data collection was at a minimum, but the trip was well worth it and I can't wait to go back on Friday.