Home Sweet Home, the American Dig House at Abydos
This summer at Abydos promised to be a busy and exciting season. The Penn research team (dubbed Team Hafla, which is Arabic for “party”) returned to Abydos after an exciting winter season with the discovery of King Senebkay and the Lost Abydos Dynasty. We were ready to continue exploring the cemetery around Senebkay as well as other sites in South Abydos. What made this season so exciting were not only the opportunities to excavate, but also the chance to be part of the application of new technological methods at South Abydos as well as the chance to perform background and survey research on the forgotten sacred lake associated with the Osiris temple. Since I have a lot to talk about, I will split this into two blog posts, with this one focusing on technology and a later post on the sacred lake project.
The Penn Research Team- Front row: Alexander Wegner. Middle row beginning from left: Matt Olson, Shelby Justl, Lisa Saladino, Dr. Jen Wegner. Back row beginning from left: Paul Verhelst, Jamie Kelly, Dr. Kevin Cahail, Dr. Rasha Soliman, Dr. Joe Wegner.
Before I start talking about the technological methods we used at Abydos this summer, I will give a little background about the site. Abydos is located in the mid-section of Egypt, about 300 miles south of Cairo. Established during the Predynastic Period, Abydos was the burial place of the First and Second Dynasty Egyptian kings and continued to develop through the Greco-Roman Period as a settlement and cemetery due to its association with the cult of Osiris. Current Penn research focuses on the Middle Kingdom Senwosret III tomb enclosure and town site of Wah-sut, the Second Intermediate Period tomb of Senebkay, and the New Kingdom cemetery located to the north of the Senwosret tomb enclosure.
Even though my title only mentions LiDAR, we utilized multiple technological methods this summer at Abydos including magnetometry and ground penetrating radar. Since I was involved with the magnetometry surveys, I will talk about this technology and the experience we had with it this summer.
Magnetometry involves a survey of an area with an instrument that measures fluctuations in the earth’s magnetic field caused by buried archaeological features. The main archaeological features we were hoping to find are mudbrick walls, which would indicate the possible locations of additional structures and tombs. These features appear as a line of black dots when the data from the magnetometer is processed and geo-referenced on a map. Sometimes these black dots seem to form the walls of a structure; however, a lot of the time these black dots are other magnetic objects like fired bricks and pieces of metal, which can be misleading. The goal of this season was to explore the area around the tomb of Senebkay with the anticipation that there are additional tombs in the area.
Dr. Kevin Cahail conducted the magnetometry survey at South Abydos this season. Almost every day Kevin strapped the 50 pounds of equipment to his back and carried it around the site conducting the magnetometry survey. At this point carrying around a 50 pound instrument may not sound so bad, but when you factor in the heat (some days it could get around 110 to 120 degrees Fahrenheit), the uneven, sandy terrain and malfunction equipment, it makes it a little challenging to focus solely on recording data and staying focused. Kevin gave me the chance to conduct a survey for a day and I have to give him a lot of credit because it was definitely hard work. After this experience, I let Kevin handle the surveying for the rest of the season. I reserved myself to setting up the survey transects for Kevin rather than carrying the magnetometer.
Dr. Kevin Cahail conducting a magnetometry survey at South Abydos.
One of the major obstacles to the magnetometry survey at South Abydos was the power lines that run across the site. The electricity given off from the power lines caused problems with the magnetometer’s computer memory, usually resulting in a complete loss of data gathered that day. Even with the power lines, Kevin was able to process the data from magnetic surveys conducted away from the power lines. From the array of black dots, Kevin was able to identify new areas of interest where future excavations will one day take place.
From magnetometry, we will move on to LiDAR, which was the technology I focused on this summer. LiDAR stands for Light Detection And Radar and is usually applied for remote sensing and three-dimensional (3D) modelling. Both methods involve using an instrument that shoots out a laser and measures the distance it takes the laser to hit a surface and reflect back to the instrument, which creates a point. The LiDAR instrument continues to shoot out the laser and measure each beam’s distance, which creates millions of points and results in a high-resolution scan of a surface. The goal this season was to use the LiDAR to make 3D scans of Senebkay’s tomb, Senwosret III’s tomb and any other structures discovered this season.
Conducting a LiDAR scan of a structure, like the tomb of Senebkay, requires planning before I can start scanning. Before I started scanning the tomb of Senebkay and other structures, I made a rough overview plan, which served to help me identify blind spots and set up reference points. The LiDAR instrument can only create a point from what it can “see” with the laser, which means that multiple scans are needed in order for every surface to be captured. By creating a rough plan, I am able to figure out where I need to place the LiDAR instrument to ensure that the final 3D model is not missing any surfaces of the structure. Another thing the rough overview plan helps me to do is set up reference points needed in the later processing of the scans. In each scan, I want the LiDAR instrument to be able to see as many of these reference points as possible since it will make the later processing easier. Usually, I do this rough overview plan of a structure the day before I actually start scanning, which gives me the time to evaluate the best way to conduct the LiDAR scan.
The LiDAR instrument and spheres set up in the tomb of Senebkay
On the day of a scan, I tried to start as soon as possible in order to avoid the sun since its rays can disrupt the laser and the heat can cause the LiDAR instrument to overheat and shut down. I then went around and set up the reference points that came in the form of white spheres set up on small tripods, which left them open to various interpretations by my team members. My favorite interpretations of them are as alien viruses or spaceships hovering around a mother ship. Once my spheres were set up, I place the LiDAR machine in the first scan location. As soon as I hit the start button, I moved out of the LiDAR instrument’s line of sight as it rotates 360 degrees to scan the structure and capture pictures of the structure used to add color to the scan during processing. After each scan, which usually lasts 13 minutes, I moved the LiDAR to the next scan location and continued scanning until I felt like I captured every surface and angle of the structure.
The next step is to begin processing the scans into a single 3D model, which involves loading the scans into a LiDAR program designed to create 3D models. In this program, I began by identifying the spheres and numbering them. Since the spheres act as reference points and are visible in the multiple scans, I can use them to merge or stitch together multiple scans of the structure into one model. This allows me to eliminate blind spots and create a high-resolution 3D model of structures like Senebkay’s tomb. After all the scans are stitched together, I can then remove any random points, which improves the model’s appearance. When finished, I will have a high-resolution 3D model.
A LiDAR scan of Senebkay’s tomb
Just like with magnetometry, the LiDAR was not without its issues. Overall, scanning was less difficult with setting up the LiDAR instrument, running the instrument and not over-heating the instrument during the day. What was more difficult was re-learning how to process the scans. At the beginning of the season, I had to draw upon the LiDAR skills I gained back in 2011 as well as get used to a different type of LiDAR instrument and processing software. Even though processing the LiDAR scans involved some stressful days, I continued to gain knowledge about processing the scans through determination and the assistance of colleagues who are experts in using LiDAR. I thought I would never say this after all those stressful days, but I have come to enjoy processing LiDAR scans and making models. These models are an important tool since it allows Joe and Kevin to bring back a scaled, high-resolution model of different structures to continue analyzing as well as preserving the structure in case of possible deterioration. I am sure the models will also serve as a cool addition to presentations as well.
What magnetometry and LiDAR represents for me is the continued experience of different technologies in the field. Ever since experiencing the use of technology during a field school in Jordan through the University of California: San Diego, I have strived to learn different technological methods in order to understand how they can be utilized on an excavation. In future excavations at Abydos, I hope to continue expanding my knowledge of magnetometry, LiDAR, and other technological methods.
Pictured are Dr. Kevin Cahail and Dr. Joe Wegner, who were our grill masters, along with Shelby Justl and Lisa Saladino, who are anxiously waiting for the final product
Even though we were busy at Abydos, it was not all work for Team Hafla. On our days off, we did numerous activities to liven up the desert. These activities included sightseeing in Sohag and Luxor, hiking through the nearby wadis, playing homemade games like ring toss and beanbags, having a water fight, and attending a local Egyptian wedding. By far my favorite activity was the day we grilled because it is not summer unless the grill is out, even at Abydos!
The final product: grilled chicken and vegetables, macaroni salad, green salad, and bread
One last bit of fun I had was to convince Team Hafla to take the group photo with a LiDAR scan. I am sure that many people are wondering what those white balls Matt, Kevin, Shelby, Lisa and Jen were holding in the group photo from the beginning of this blog. These are the spheres used in LiDAR scans as reference points and even though they are not acting as reference points in our group scan, they are too much of a feature to leave out of a LiDAR scan. For now, I will leave you with a 3D model of Team Hafla and will return soon to talk about my other focus at Abydos this season, the forgotten sacred lake associated with the Osiris temple.
The Team Hafla Group LiDAR scan