Mapping Ancient Grounds
From December 2000 to February 2001, Archaeos, a small non-profit organization based in New York City, conducted the first of a multi-season mapping project in Vijayanagara, India. From the beginning of the 14th to the end of the 16th centuries, Vijayanagara rivaled the greatest medieval and renaissance European cities in size, wealth and population. It controlled an empire of the same name well known to European travelers.
Vijayanagara was sacked and abandoned more than four centuries ago but the current extent of the city’s structural remains still correlate with the wondrous accounts of European travelers. Archaeologists now know that the core of Vijayanagara known as the “Central City” consisted of a fortified royal residential quarter and a separate series of bordering temple-centered religious communities that once occupied an area of approximately 20 square kilometers.
The project members, Dr. John Fritz, Andy Leung, Ian Stell and I, concentrated on mapping a topographical feature known as the North Ridge, which covers approximately 30 square kilometers and is centered between royal and sacred precincts of the urban core. The project’s focus was to survey an area where important historical remains have already largely disappeared due to human pressures upon the archaeological environment and to aim for a maximum recovery of any and all surviving information visible on the surface. Because the project focuses on recording surface remains, as opposed to excavating them, it was thought that Archaeos should eventually be able to map a large portion of the extensive building and habitation remains.
An Archaeological DilemmaArchaeology as a whole is predicated upon the need to find solutions to discover and record hidden and/or often disappearing forms of historical data. One can understand the problems archaeologists face by studying the case of Vijayanagara. One could ask about the current threats to preservation of remaining historical evidence at the site, and what techniques and technologies can be immediately, realistically and cost-effectively employed to record and interpret the remaining evidence for the historical record.
We know from texts that the Vijayanagara Empire was founded in 1340 by a newly established dynasty of kings who succeeded in expelling the Muslim invaders from southern India. These new kings established their power base by consolidating the many smaller polities and political groups with a new kingdom, which lasted just over two centuries. In 1565, however, a strong Muslim military alliance under the leadership of the Sultanate of Deccan succeeded in reconquering the area, burning much of the city to the ground, slaughtering its rulers and defacing its temples. Following its destruction, the capital ceased to be occupied again. Worship at Vijayanagara’s many sacred shrines never wholly ceased, but the majority of the site was soon reclaimed by the surrounding wilderness.
Today, Vijayanagara is a UNESCO World Heritage Site and the first site in India to be officially declared “endangered.” Although two government groups, the Archaeological Survey of India and the Department of Museums and Antiquities of the State of Karnataka, are dedicated to maintaining the site, their resources are limited. Furthermore, the government must also balance the concerns of managing and safeguarding the site with the reality of diverse social and economic forces. Today, the ancient city lies within the center of a densely populated agricultural community whose needs threaten the conservation of historical remains. Although many of the city’s temples, walls and other structures still stand, a great many of them continue to be stripped of building materials in order to build farmers walls, construct new buildings, or clear new fields to make way for agricultural development.
Ultimately, the need for conservation and protection of the site must be balanced with the more realistic and immediate human pressures of a developing country in which poverty and overpopulation are also epidemic. Because of these competing social forces, archaeologists must accept the fact that although damage to the existing remains of the site may be slowed, they cannot be stopped. The mission of Archaeos at Vijayanagara is therefore to utilize surveying, photographic and video technologies to record as much historical information as is still possible before it disappears. In so doing we are engaged in an ongoing process of experimentation with new technologies and new techniques for recording information.
Choosing a New Point of BeginningThe North Ridge at Vijayanagara is more than two kilometers in length, so the first step upon arriving at the site was to walk along the area for several days with members Dr. John Fritz, the project co-director, and Andrew K.Y. Leung, the assistant director. As the co-director along with Dr. George Michell of the Vijayanagara Research Project (VRP), Fritz has been working at the site for more than two decades and was the one to propose this particular project to Archaeos. He is also one of the scholars most intimately acquainted with the site, its history and its topography. With the benefit of his advice, we eventually decided to focus upon an area of approximately 25,000 to 50,000 square meters along the southwestern end of the North Ridge. The area contains a very high density of building remains, including the remains of a small palace and at least one other large elite complex.
One of the initial problems facing us was the lack of any accurate bench marks to base our coordinate system on. Although surveying marks belonging to previous teams litter the countryside, it is no longer clear who most of them belong to or whether they are accurate. Leung and I therefore decided to set up a large, closed traverse containing three primary survey points, A1, A2 and A3, each located far from the others and on a high observation point. Since we did not have any accurate reference point to calculate true North by, our total station, an old Topcon GTS-3B (Topcon Positioning System, Pleasanton, Calif.) was used to shoot the bearing of the North Star in relation to a temporary backsight. The time of the shot was recorded for future reference. The time itself was calculated by synchronizing the clock on our data collector, a Psion 5mx hand-held computer, to a signal beep that is regularly transmitted by the BBC so that its many remote listeners may calculate the correct Greenwich Mean Time (GMT).
We set up the first of our permanent stations, A1, on the roof of a small temple constructed on top of a large boulder during the Vijayanagara period. We were fortunate in that a bench mark had already been blazed onto the center of the rooftop by some long forgotten surveying team; this was assigned the North-South/East-West coordinates “0, 0”—our new point of beginning. Its approximate elevation then determined by using the total station to shoot an older bench mark clearly visable on 1:400 survey maps produced in the 1980s by local surveyors, using alidades and transits, on behalf of the Vijayanagara Research Project. Situated on top of a large hill about a kilometer away, this proved to be a difficult shot through the haze of the large valley between me and Leung.
A local stonemason was hired to chisel two new markers onto the rock surfaces where we positioned stations A2 and A3, the first on a high bluff to the northeast of A1 and the second on a flat granite formation to the southeast. So archaeologists will be able to quickly relocate these stations in the future, GPS readings were also recorded at each of them using a Magellan GPS 310 (Magellan Corp., Santa Clara, Calif.).
While Leung and I finished closing and calculating the accuracy of the traverse among A1, A2 and A3, other aspects of the project were also taking place. Approximately 30 workers employed by Archaeos, but supervised by officials from the Directorate of Museums and Antiquities of the State of Karnataka, were clearing bushes, cacti and tall grass from the intended survey area. Following the path of the clearing process, Fritz and his assistants were marking the many thousands of features to be surveyed using a paint composed of white lime. The point of this was to make any significant features to be surveyed easily visible from a distance. As lime is water solvent, it has the added advantage that it will wash away several rainy seasons, thus avoiding any permanent damage to building features or other cultural artifacts.
Structuring and Streamlining Data CollectionOne of the most important features of Archaeos’ mapping project at Vijayanagara is that it includes a series of ongoing experiments about how archaeological data is collected, and eventually modeled and interpreted. Because each and every surveying point we shoot at the site must be linked to as much pertinent information as we can reasonably record, the choice of data collection hardware and software is extremely critical. Whereas almost any total station, such as our decade old Topcon GTS-3B, would fulfill most of our basic needs, our choice of data collectors has far-reaching effects upon the types and amounts of information we can collect, as well as how that data is eventually structured and interpreted.
During an earlier 1999 excavation season at Tell Arbid in northern Syria, Archaeos utilized an older, commercially available data collector to map the remains of its excavation trenches. Although the unit proved to be practically indestructible, users complained that its alphabetically ordered keyboard was clumsy, its screen was too small, and its interface was confusing. A more severe shortcoming was that all of the software we encountered for it seemed limited in terms of assigning long or complex descriptions to each point shot.
In “surface archaeology” projects such as the one conducted at Vijayanagara, there is no excavation involved. Instead, archaeologists record as extensively as possible those features visible on the ground. One of the main features we commonly record, for example, are the surviving foundation courses of stone walls and of destroyed buildings. We are particularly fortunate at Vijayanagara because it sits on a series of hills and valleys composed primarily of granite. This means that many of the ancient city’s architectural and structural features were cut directly into the metamorphic rock. These different types of distinct features are still clearly visible and can be divided into hundreds of unique categories such as: door pivots, anchor holes, mortar holes, beam sockets, quarry marks, rock cut oil lamps and sculptures.
Because we would be surveying a large area filled with highly diverse types of surface remains, we decided to replace our data collector software with Prosurv 2000 software (Prosurv, LLC, Powell, Wyo.), which has a high degree of programmabilty and modification flexibility.
The most important thing Prosurv 2000 allowed us to do was to customize two forms of data that are entered with each point we shoot: control codes and feature codes. Control codes function as a set of instructions used by Vectorworks (a Computer Assisted Design program) to draw lines and points. They are used to instruct the CAD program that each and every survey point is one of the following: (see chart)
Whereas the control codes listed above instruct the CAD program how to draw the surveyed points, the feature codes act as a relational database that contains several levels of nested information describing each specific point in detail. Prosurv prompts the user to enter the required data each time, though by default entering the last value put in each field to cut down on repetition of data entry.
Each line of data collected contains control code, point number, X, Y and Z coordinates, and the feature code followed by its associated subcategories of information. An example of a typical line of data exported from the data collector is as follows (N.B., in the original output form, tab stops are used to delineate breaks between each segment of information): (see chart)
In this example, lines 7, 8 and 9 are all subcategories of the feature code PLFB or “pillar foundation block.” Each and every type of feature code is assigned so as to prompt the surveyor to enter the appropriate subcategories of information.
During the first field season, 141 such feature codes, each with its associated subcategories of information were employed. The ability to customize these codes has allowed Archaeos to gather what is probably an unprecedented amount of information about every point shot during an archaeological survey. As well, we were able to incorporate the large range of feature codes already in use at the site by the Vijayanagara Research Project, which has been studying the area for 20 years. In total, 14 different revisions of the feature codes were compiled during the first season in order to streamline the data collection process.
The Final StepThe final step in the daily surveying process at Vijayanagara was to download the Prosurv 2000 each day onto a pair of Macintosh Powerbooks and import the data into Vectorworks. Prosurv offers pre-defined and user-defined styles for exporting the data, however, a tab-delimited style was not supported. Therefore, we wrote a small script for BBEdit—a Macintosh-based text editor—which placed the fields of data into the correct tab-delimited format needed for import into Vectorworks. The recent revision to Prosurv 2000 (version 3.0.0) now allows data to be exported in tab-delimited form, so this step will no longer be necessary in future seasons.
Once the daily data was correctly formatted using the BBEdit script, it was then routinely viewed in Excel where any glaring errors in data input on the part of the surveyor were more clearly visible given the divisions of information into columns. Following this final check, the data was then imported into Vectorworks using another set of scripts in its native scripting language.
The result of this entire process is a hybrid solution to archaeological data collection in which the Archaeos North Ridge Mapping Project has been able to collect, model and analyze data specifically defined by archaeological reasoning, rather than by the usual limitations of hardware and software. When we view any individual shot on the map generated in Vectorworks, we can click on the point and view all of the data collected as feature codes and their subcategories. We can also query the data to see how many of any given feature exists within a defined space. This offers Archaeos’ archaeologists new ways of interpreting information. A large number of mortars or grindstones in a particular area, for example, might indicate a high level of agricultural processing and economic activity. Without the custom written feature codes used by Prosurv 2000 during the data collection stage, this type of analysis would be difficult, if not impossible. Similarly, although many ancient buildings may have disappeared, large concentrations of rubble mounds (one of our feature code categories) containing architectural elements such as pillar foundation blocks, roofing slabs or door lintels (subcategories) allow us to roughly interpolate the density of structures that originally existed within a given area.
A Positive EvaluationArchaeos’ first season mapping the North Ridge at Vijayanagara was conceived partially as a test project. One of its aims was to see what differences new technologies of mapping could bring to augment the methods being used by the Vijayanagara Research Project during their 1:400 mapping project conducted during the 1980s. Another was to see if the study of previously unmapped areas would bring information that would significantly alter the previous views of the settlement patterns or spatial layout of the city.
By utilizing state-of-the-art surveying technology, Archaeos has been able to bring a greater degree of accuracy to the ongoing documentation process. Although upon initial visual inspection the North Ridge today appears to have been largely uninhabited in ancient times, the results of the mapping process has already yielded a very different picture. It is clear that this was a highly populated area within the city’s urban core. The numbers and the massing of architectural and other cultural remains along the surface of the North Ridge, in fact, indicate dense urban development. And now that many of these disparate features have been mapped, they can be more easily understood as the remains of coherent structures and indicators of economic and social activities.
As we continue to enhance our mapping and data collection capabilities at Vijayanagara in future seasons, it will become increasingly possible to better reach an understanding of the layout of the city and its functions.