Abstract The Atta project maps tunnels and chambers of a vast leafcutting ant colony. An 8x8 meter Ground Penetrating Radar scan was translated into a 3D model that can be viewed on an immersive visualization system, scaling the viewer to ant size. The system developed by our team is nondestructive to the ants and is the first time GPR has been used to map a living ant colony. To achieve this goal, the project combined the site-specific nature of an indexical system, GPR, with the ability of an algorithm to parse the data. As a result, the model retains a formal connection with its subject and can be transported anywhere, to be viewed in many different ways. O ne of Texas’s smallest natives is also one of its largest: myrmecologists refer to ant colonies as superorganisms. Atta texana, indigenous to Texas and Louisiana, harvests tree leaves to farm a fungus in vast, underground cavities that can spread over more than an acre of land and reach to great depths, with over a million ants in residence. [1] Excavated leafcutting nests have proven large enough to contain a 3-story house. [2] Scientists believe the ants’ symbiotic relationship with the fungus could lead to discoveries in medicine and sustainable agriculture. [3] I set out to map an Atta texana nest. I imagined lifting a section out of the ground and turning it around in space, to view it like a sculpture. Previous attempts to model ant colonies have been undertaken by myrmecologist Walter Schinkel, whose technique involves pouring casting material into the nest, digging it up and piecing it back together. Schinkel has stated, however, that an Atta colony is so large this technique would be quite a challenge. [4] [Figure 1] Another means to map ant colonies involves using a bulldozer to scrape away successive layers of soil and measuring the diameter of the holes. This results in a kind of abstract image composed of disconnected shapes. Tunnels collapse with this method and cannot be tracked. [5] If measurement is the goal, either approach would be ideal. But what I wanted was to gain a unique view of this subterranean architecture using a method that would not disturb the colony. Ground Penetrating Radar (GPR) provided a means to map the Atta nest. Using GPR, high frequency radar pulses are sent from a surface antenna into the ground. Elapsed time between when the pulse is transmitted—reflected from buried materials or sediment and soil changes—and when it is received, is measured. The sender and receiver are moved along the surface, following transects of a grid. [6] Typical uses of GPR include mapping buried archaeological ruins, and locating unmarked graves, unknown caverns, earthquake faults, and lost pipes or power lines. GPR provides an indexical image, formed by the action of radar pulses passing through substances over time and distance. In this way it can be compared to a photograph, formed by the pattern of light striking a photosensitive surface. Photographer Henri Cartier-Bresson described taking a photograph as fixing a “decisive moment,” a confluence of the artist’s position in relation to the geometry of an unfolding event. [7] Photography offers what Roland Barthes termed the punctum, the preservation of a specific feature of the subject that cannot be separated from time or place. The punctum gives rise to a “third meaning,” an indefinable experience of specificity which cannot be essentialized. [8] Conversely, digital representations often rely on generalization of physical phenomena. Gravity, water, or terrain are simulated with algorithms, freed from substance and geographic locale. Because of its mathematical structure, the algorithm attains a level of fluidity, and can be repurposed from one form to another. [9] In mapping an Atta nest, I wanted to maintain a connection with this particular subject, deep in the soil of a Texas field, while simulating the colony architecture in a form distributable across time and space. Geophysicist Carl Pierce worked with me to scan a portion of the site. It was a vast area, but only a small section of the entire nest. It took three days to cover the 8-meter grid in 10-centimeter slices. We used 200 Mhz antennas, which provided the best balance between resolution and depth. The scan penetrated 3 to 5 meters beneath the surface. Typically GPR scans contain noise which can interfere with the results. [10] Soil composition, radio interference, and magnetic properties of substances can all contribute noise. The area scanned had once been trucked-in, sandy soil. Besides air, sand is one of the best mediums to conduct a GPR signal. Carl Pierce used proprietary GPR software to “dewow” the data. This is technically known as a signal saturation correction. It accounts for the inductive response of the transmitted radar pulse. The data can then be filtered in many ways to reduce or eliminate noise. In this case a spreading and exponential compensation (SEC) filter was used to account for the geometric spreading (picture the pattern made by a single raindrop in water), and exponential decay of the radar wave strength with depth. This is the closest filtering that mimics reality at the time the data was processed. We set out to differentiate voids from soil and other materials. The velocity of radar waves in air is the speed of light — 3.0 x 10^8 meters per Figure 1: Myrmecologist Walter Tschinkel with Pogonomyrmex badius colony plaster cast. Photograph by Charles Badland. Atta texana leafcutting ant colony: a view underground Carol LaFayette, Fred Parke, Carl Pierce, Tatsuya Nakamura, Lauren Simpson