The Past Meets the Future: Reconstructing with Computers
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Archaeologists working around the globe are discovering that ancient artifacts and architecture may now be better understood by applying advanced computer technology. Computers can give archaeologists invaluable assistance with mapping and creating models, cataloging and performing statistical analyses. Some archaeologists are even taking portable computers right into the trenches, though more are using them at field headquarters and still more in university offices.
The most dramatic application of computers in archaeology is the CADD program—Computer-Assisted Drafting and Design. CADD programs have a long history in architecture and engineering, but they have only recently become available to archaeologists. These programs store location and dimension information with great precision; they provide visualization aids and they automate the production of paper drawings.
Several years ago, when CADD programs began to be used as mapping aids, their output was only two-dimensional. Even such limited programs made possible excellent maps and plans; time-consuming redrafting so often required, was eliminated because the drawings could be easily modified at various scales.
Now, five or six years down the road, current state-of-the-art CADD programs are far more capable, making possible the creation of fully accurate and complete three-dimensional computer models. The computer can provide views of the models on screen or on paper—as if they were full-scale physical models—from any direction and at any scale. Plans, elevations, sections and perspectives can be produced very easily. One may focus on only a very small portion of a large model in order to see fine details or on all of the model on a smaller scale.
CADD can store data as segments of one model. The user may divide the model into as many segments as desired. Segments may include only an individual item, groups of similar items (pots, tools, etc.), parts of structures (columns, walls, etc.) or even an entire building. After the model has been segmented, an archaeologist may then view any combination of the segments at any time, from any angle, at any scale. Pots can be separated from coins, tools from weapons, walls from floors, old walls from older walls from yet older walls, and so on. The possibilities for segmenting the material and then viewing the segments in different and illuminating combinations are almost endless. (For example, in the building discussed below, the building blocks of marble may be displayed separately. When they are, it becomes clear that two of them must originally have stood adjacent to the other marble blocks rather than where they stand today, separated from them by five vertical limestone blocks.)
One of the most detailed applications of CADD attempted so far has been carried out by the author on material from the entrance to the Athenian Acropolis, which was demolished to make way for the famous fifth-century B.C. Propylaea. Remains from the earlier structure (actually, three building phases in the early part of the fifth century B.C.) have been “drawn,” mostly by typing the three-dimensional coordinates of individual points into the computer. The drawing can be viewed in various orientations.
As an example of what CADD can do, we show several drawings of the excavated gateway at the Acropolis. The actual site is cramped by later construction that prevents viewing the gateway from a distance. The computer, however, can draw the area from a position farther away from the gateway than a person can stand. From stored data the computer generates a three-dimensional drawing that shows exactly what has been found. It is instructed to add missing but obvious elements, such as the continuation of stair treads and portions of walls. The archaeologist then adds presumed structures to the drawing. A plan 061showing the area as it appears from above may easily be generated and the three-dimensional model may be rotated to show the site from different perspectives.
The CADD program can only draw those features for which it has stored data or those features that its operator instructs it to put in. The computer is a dumb but extremely useful instrument. Probably its greatest asset is that the computer gives the archaeologist the ability to select what will be drawn—choosing some elements, perhaps from a particular time period, and excluding others that may confuse understanding. Everything the computer does could be done by an archaeologist/artist. But the CADD program offers ease, speed and greater accuracy, as well as a permanent record for the student or scholar to return to in the future in order to understand an excavation nearly as well as the excavator did years before.
Today several three-dimensional programs are available. AutoCAD is by far the most commonly used. It has several important advantages for scholars in addition to its 3-D drawing capability. One, it can be used on a variety of computers (PCs, Macintoshes, Suns, etc.), and its data files may be exchanged from one computer to another without alteration. Two, it is so widely used that the program itself and training in its use are available worldwide. Three, virtually all peripheral equipment designed for general CADD work is designed first to work with AutoCAD. There are even two magazines (Cadence and Cadalyst) devoted to AutoCAD. AutoCAD has a list price of $3,500, but it is available from the manufacturer, Autodesk, Inc., 2320 Marinship Way, Sausalito, CA 94965, at substantial discounts for academics. Other programs range from $1,000 to $5,000.
New programs will soon add, at a reasonable price, the ability to render these images with shadows, reflections, textures, colors and so on. We will then be able to make a drawing that will seem as “real” as a photograph.
Every excavation must have a catalogue. Using the computer to keep a catalogue is not new or startling, but it is now possible to link the artifact catalogue to any number of other databases so as to broaden the utility of all. For instance, when dealing with wooden artifacts, one may want to know the common name of the wood, its scientific name, the characteristics for working and wear, growth habits, etc. But that information would clutter an artifact catalogue unnecessarily. The solution is to put into the artifact catalogue only the scientific name of the wood and to maintain a separate database with information about different woods; the object may then be linked to the wood database via the scientific name. Someone checking on a wooden artifact in the catalogue could call up only the artifact information or specify that the appropriate information from the wood database be displayed as well; the information in the wood database could also be used to select items from the catalogue (for instance, search for all objects made of a wood with specified growth habits). Such linked databases make it possible to access far more information and to do so economically and conveniently.
The most thorough use of the capabilities of such linked databases in archaeology is the Lexicon Iconographicum Mythologiae Classicae (LIMC0). The database consists of a number of related data files. Files containing catalogue-type information about artifacts with mythological scenes are the core, of course, but linked to these are additional files with information about museums where the objects may be found, artists who made them, gods and goddesses depicted on them, archaeological sites from which they came, bibliography and so on.
This technology is also being applied to excavations (though more slowly because of the organizational work required) in places as far apart as the Anatolian 063plateau and the rolling hills of southern Indiana.
Perhaps the most exciting thing about the linked databases is that soon it will be possible to relate these database files to CADD files so that the CADD file is simply one more of the linked files. As a result, one could take the drawings in this article and ask for information about any stone in them. So long as the stone had been catalogued, the information would be immediately available. Of course the real utility of such programs would be with artifacts, not marble blocks.
Modern archaeologists increasingly try to squeeze more information from their finds. They recognize that resources for excavation are too limited to be wasted and that there are possibilities for gaining important insights by applying statistical analyses to large collections of seemingly trivial items. Archaeologists today apply statistical tests to collections of bones, pottery sherds, seeds, stone tools and even the chemical composition of various metal implements.
Surprising things can be learned by analyzing bones, for instance. At Gordion, Turkey—the site where King Midas is thought to be buried—analysis of bones has shown that wild deer represented the most common meat in one period, but domesticated sheep and goats were more common in the previous period. This information surprised the archaeologists because it suggests a change in the level of sophistication of the inhabitants that is the reverse of what one normally expects. Only by examining a large collector of bone samples and using statistical tests could this information have been discovered.
The availability of statistical packages for microcomputers has made these kinds of analyses far more common; we are indeed learning more from our material as a result. Information about diet and the ecosystem is especially likely to emerge from statistical analyses. Archaeologists are accustomed to making assumptions from a few samples of large and significant objects, but statistical packages make it possible to reach conclusions based upon large collections of small, individually insignificant objects.
If there is a down side to the increasing use of computers, it is that we may rely upon the computer to think for us by accepting the programs (which are, after all, designed and executed by people) as if there were no way to ask different questions or to find different ways of looking at the data. We must be wary of that possibility, but, with prudent use of computers, archaeologists can glean nearly all possible information from a site. At the same time, computers make the raw data far more widely available to scholars. Thus not only can we know more today with the aid of the computer, but those who follow will have better access to the original data and will be better able to reconsider our problems many years hence. Moreover, with access to full records of an excavation, one may study it well and thoroughly even if it has never been published.
Archaeologists working around the globe are discovering that ancient artifacts and architecture may now be better understood by applying advanced computer technology. Computers can give archaeologists invaluable assistance with mapping and creating models, cataloging and performing statistical analyses. Some archaeologists are even taking portable computers right into the trenches, though more are using them at field headquarters and still more in university offices. The most dramatic application of computers in archaeology is the CADD program—Computer-Assisted Drafting and Design. CADD programs have a long history in architecture and engineering, but they have only recently become available to archaeologists. These programs […]
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