Courier TheNational Park Service Newsletter Vol. 3, No. 11 Washington, D.C. October 1980 Remote sensing: Tool for the park manager planning tool, it is probably the latter he would choose. "Remote sensing" is a general label applied to a series of devices that record on film, magnetic tape, seismic charts, etc., the physical characteristics of the world we live in. These recorded data do not necessarily duplicate the studied feature. As every home movie buff knows, no photograph reproduces reality without some haziness, flatness, or other form of distortion. Nevertheless, there are ways of making allowances for such inaccuracies. The real work-horse of these allowances lies in an interdependent system of electronic data analysis equipment. In highly qualified hands, this equipment helps interpret electromagnetic and photographic evidence so that the characteristics of the studied feature can be more accurately displayed. Justification for this hi-tech Computer machinery utilized in remote sensing verification. equipment was vividly demonstrated a decade ago at Mesa Verde. In the 1960s magnetometry survey data on a buried By Mary V. Maruca the parkland, and what the tangible Mesa Verde structure could only be Anthropology Division, WASO remains of that occupation were. plotted by hand. As a result, none of the Park managers have never had as site features showed up. The Suppose you were the new readily available as they have today the conclusion—magnetometer surveys superintendent of a national park. You services of specialists, e.g., geologist, could not plot buried features. Then in were familiar with the complexities of anthropologists and biologists. The the 1970s the same data was replotted, visitor operations, maintenance and diversity of highly skilled Service em­ this time on a computer. With the interpretation; in short, you were the ployees is such that the manager can computer's infinite plotting capabilities, perfect veteran for the job. However, draw on the specialized talents of, among all the features showed up. you were also confronted with a others, archeologists well versed in The business of adjusting for problem, and a fairly serious problem at magnetometry and aerial photography. photographic distortion is carried on in that. Information pertaining to the In ways which have never been so readily tandem by various types of equipment. A natural and cultural resources of your available, the manager can lay hold on light table is used to view positive or park was sketchy, variable in quality, and the broader perspective—the position of negative film transparencies; a color not organized in any usable format. You his park within a larger physiographic, monitor can bring out the one or more had several planning documents, but, climatic and cultural context. The colors arbitrarily assigned to the grand beyond those, there was no concrete manager who needs an inventory of scale density levels within the data on all of the resources you were cultural resources could have a field crew photographic negative, making patterns charged with managing. Decisions of archeologists make a complete, on- more visible to the human eye; an edge affecting the location of trails or a new the-ground survey, which could take enhancer picks up images from a visitor center had been postponed, weeks, months, or years depending on negative on a light table and offsets them pending further study of the resources. the park's size (it took 13 years to in such a way as to make certain linear or Faced with this dilemma, you might be complete the survey of Mesa Verde). Or curvilinear features more visually tempted to isolate one portion of your he could call on those self-same pronounced. Stereo-paired research problem, i.e., climate changes archeologists familiar with photographs, both aerial and land-based, over time, or Native American magnetometry and aerial photography— provide a whole other set of remote occupation, and concentrate on that. Or remote sensing techniques. Considering sensing information. Two photos are you might desire a broader perspective, the usefulness of remote sensed taken of the same field, river bed, etc., such as the scars occupation had left on information as a monitoring and Continued on P. 2 Stereo-paired photographs provide another set of remote sensing information. may or may not represent a cultural feature. In order to determine whether such a pattern is indeed cultural, the archeologist ground-checks the area isolated in the photograph. If the determination is positive, the archeologist knows that other identical photographic patterns will likely represent the same types of phenomena. "Remote sensing allows us to document a resource. By documentation I mean a highly accurate data bank the manager can call on in order to make decisions," says Dr. Lyons. "Documentation, solely through the excavation process, may irreparably alter or destroy a non-renewable resource. Fortunately we are beginning to function as consultants to the parks. As remote Aerial shot of archeological area under remote sensing study. sensing becomes an accepted part of the archeological lexicon, more and more park managers come to us with their with sufficient overlap so that both the gives the park manager abundant needs. We, in turn, adapt remote sensing horizontal and vertical dimensions of the information with which to make techniques which begin to answer their region can be determined. A stereoscope decisions affecting park resources. individual questions." merges these separate images, so that the According to Tom Lyons, chief of the viewer sees a 3-D picture. Even more NPS Remote Sensing Division in When the results of a remote sensing sophisticated equipment can be used to Albuquerque, N.Mex., "You don't put a inquiry are positive, they are convert the stereo images into contoured spade in the soil until you have some sort overwhelmingly useful to the park. But if planametric maps, and to record an of overview of what's there. This not only no ground pattern is indicated or if the infinite number of points into digital includes archeological considerations aerial photo is incapable of picking up a computer language. but geographical, ethnographical, and pattern, this does not mean it is safe for Remote sensing is not a sure-fire geomorphological ones as well." the superintendent to process paperwork for a parking lot or to instruct problem solver, but it is a useful data- Dr. Lyons' program was the first of its crews to mark out a new trail. Based on collecting, recording, and evaluating kind in the National Park Service. It recommendations, he may, in fact, tool. Its mapping and graphic display began 11 years ago as part of the Chaco decide that further research and the use capabilities have also attracted the Research Project, a 15-year program to of more traditional approaches are attention of park planners. Originally study the prehistory of Chaco Canyon needed prior to construction. At Knife archeologists made intuitive judgments and the Chacoan culture. Working in River Indian Villages National Historic regarding the physiographic and support of research archeologists, the Site, N.Dak., the ancient Indian lodges environmental context of sites they Division's staff helped to develop remote have been plotted and mapped through proposed to excavate. The technology sensed evidence of a road system, magnetometer readings and aerial that could have given them the highly ancient Anasazi in origin, stretching from photogrammetery. Knowing the location refined perspective of an aerial Chaco to outlying trade districts. This of these lodges and below-ground photograph had not then been information was then ground-checked. features from the start has helped developed. But remote sensing now Ground-checking is a necessary step in researchers study the site, aided by makes available huge quantities of high every remote sensing investigation. minimum test excavation. It has also quality data, actually gathered over vaster Basically it is a re-checking process to provided planners and managers with territory than the archeologist could determine the exact nature of the pattern precise information for early decision­ have once imagined. It is now possible to first detected on a remote sensed media making on plotting visitor use trails and speak from a more factual, less intuitive (e.g., photograph, magnetometer read­ situating the visitor center. position on the links between landscapes out). An aerial photo may show a certain and cultures. Such a vast archive of data configuration or pattern of shapes that Again, if the manager is grappling with 2 pressure from energy developers, an conditions a fire can start allows the photograph portions of the United aerial photogrammetric map of park manager to wisely deploy his staff. States. However, not until the early part boundaries can establish just how far the Infrared photography may also be a tool of the last decade did remote sensing developers can go. Depending on when of the manager, allowing him to appear as a systematized program in the park was last mapped, such a determine the percentage of arid to conjunction with archeological photographic record can also indicate wetland park areas. Shrublands, investigation. And not until 1976, did the washed-out roads, altered stream grasslands, and forests each burn at a program speak out for non-destructive channels, and overgrazing, as well as a different rate, and aerial photographs archeology as a form of protection for host of other phenomena useful to the document the proximity of each to the cultural heritage sites. management of the park. Changes within other. "Chaco Canyon was a starting point for the park go unperceived unless a In a very different kind of monitoring the program," Tom Lyons points out. photographic archive is maintained over capacity, this time at Valley Forge, "We discovered how versatile a tool we time. Without the aerial photos taken by photography helped to document how a were working with.