Feature: Rock Art in 3D
Professional Surveyor Magazine - August 2011
Reflectorless scanning helps archeologists explore and
document endangered Native American art in Arkansas.
by John Wallace
Arkansas’ archeological heritage includes one of the most remarkable concentrations of American Indian rock art in eastern North America. These art sites are priceless treasures. Etched, painted, and crafted in antiquity, they stand as reminders of a culture and a people who existed centuries before.
Ironically, their protection and preservation require technologies that encompass the antithesis of their inherent character. Precise, fast, and mobile measurement was needed to capture and accurately record their intimate detail and prevent the forces of erosion, natural elements, and potential vandalism from eradicating them.
“The irony is these are rock art sites, but they also are fragile,” said Mike Evans, research assistant for the Arkansas Archeological Survey
(AAS). “They have already dramatically changed and degraded over time. The sobering part of what we’re doing is the knowledge that some of them could disappear tomorrow. In that case, ours might be the only scientific record that’s left. We need to document them in the best way possible and as expeditiously as possible … because it might be the only opportunity we get.”
This sounds easy enough, but manpower and expertise—along with required measurement and data-collection equipment—are not without limits. Also, site access can range from moderately challenging to darned near impossible. Given these challenges, the team of Dr. George Sabo III (professor of archeology at the University of Arkansas), Tim Mulvihill (research station archeologist for the University of Arkansas-Fort Smith Research Station), and Evans determined their need for long-range scanning and imaging robotic total station capabilities.
Rock art is one of the oldest material forms of human expression and is found throughout the world. Most rock art in Arkansas was made by pre-Columbian American Indians (that is, by Indians who were living here before the
arrival of Europeans).
The first people arrived here about 12,500 years ago at the end of the last Ice Age. Their descendants, who made the rock art we can still observe today, may have been the ancestors of the historic Caddo, Osage, Quapaw, Tunica, and Wichita tribes who were here when the first Europeans arrived. Archeologists believe that most Arkansas rock art was produced during the Mississippian era (A.D. 900-1541).
Anthropologists and archeologists define rock art as images carved, drawn, or painted onto immovable rock surfaces. Images that are carved or engraved into rock are petroglyphs. Images made with paint or other pigment are pictographs. Some rock art images, such as painted petroglyphs, were created using a combination of techniques.
Archeologists recognize that different rituals took place in different locations. Rock art at secluded, hard-to-reach sites is thought to have been made during individual rites performed in solitude (for example, vision quests or puberty rites). Images at larger, more accessible sites are thought to be the result of shaman practices performed for the benefit of the wider community.
Improved Scanning Capabilities
Their system had to be capable of producing photography with dimensions to properly capture and record the fragile, complex sites; it had to be portable, and it had to be efficient. Working with Hayes Instrument Company
of Shelbyville, Tennessee, they selected the Topcon
IS total station for the job.
Previously, the team was limited to using equipment that was large and bulky, weighing more than 75 pounds, and with four large batteries “the size of a small microwave oven” to power the necessary laser scanner. “Let’s just say that it was something you wouldn’t be backpacking in,” Sabo said, which is “a real problem since most sites are fairly remote.”
“Doing field scans on secluded sites was a nightmare,” Evans said. “We needed accuracy and ruggedness. When you can set up and gather data quickly and efficiently, you can do more extensive work at the site.
“Bluff shelters are difficult to get around in. The reflectorless scanning solves a lot of that, allowing you to get back into smaller spaces. We’ve been using total stations for years and generating maps … but those older versions don’t really do bluff shelters justice. Our new system provides much more accurate depictions of what’s going on at the site.” Accessing some sites hewn into cliffs is easier because this system can reach up to 2,000 meters and can be quickly and easily reconnected if contact is lost.
Mulvihill added, “Using the older equipment for mapping took at least two people. Setting up to take each shot was time-consuming. But this system allows one person to gather more data and capture exponentially more shots in a shorter amount of time. And by reducing the garbage that has to be cleaned out of your files with the scanning feature, you improve the editing process when you’re through capturing your data—bringing up something you can use right away.”
Piecing together the Big Picture
The art (and its history) has been a fascinating subject for scanning. “The ‘wow’ moment for me,” Evans said, “has been the realization that each of these sites was a small piece of a bigger picture, and that it was important that we gather each piece thoroughly and consistently so that they could be used in understanding the larger cultural context someday.
“When I’m recording the sites I just try to keep an open mind and try to not miss anything that might be important by making as complete and accurate model of the site as possible,” Evans continued. “Hopefully, through the information we are able to harvest, a better understanding of the big picture will develop as we continue to catalog and record these sites.”
Mulvihill said he has developed a much deeper appreciation for the Native American Indian culture through the work. “You could tell it was a special place to the people who created the images.
“Their spiritual world intertwined with their everyday world,” Mulvihill continued. “Getting just a glimpse into why they might have created these images and these places is an amazing experience. I don’t think we’ll ever have a complete understanding because it can be so intricate, but we can get some small idea of why they created the images.”
Evans expanded on that thought: “I see the rock art sites as a very small part of a much larger cultural landscape, sites that were probably used for very specific purposes. Our understanding of that larger cultural landscape is very limited. Therefore, my personal goal while recording the sites is to gather as many details about the site and surrounding area as possible so that those details can be available for future research.”
Evans explained that scanning offers huge benefits for the rock art exploration and documentation efforts—generating high-quality scans “that blew us away and that can be used immediately in our research.” Also, educators and their students benefit from the ability to access and view 3D models of the rock art sites. Three-dimensional models give viewers a more accurate, detailed snapshot of how the sites were arranged, actually allowing the viewer to experience a virtual walkabout around the site. Conventional photography—even with panoramic views—cannot convey that same experience.
“You can take that 3D model and embed it in a larger digital model that can be thought of as a sphere or globe. That allows you to take the viewer even deeper inside,” Sabo said. Augment that with digital photographs, and the viewer can be transported inside the shelter looking out—a virtual recreation of the visual experience Native American Indians had centuries ago when they created and used these sites for vision quests and other rituals.
The irony is that despite its inherent nature, rock art is not impervious to natural or human threats. For that reason, Mulvihill noted, “I’m just glad that detailed recording is taking place on these sites. Time and vandalism are destroying a lot of these sites and it is important to me that some record be made of what was here.”
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John Wallace is president of Wallace Communications, providing strategic communications counsel and media support to technology-oriented companies.
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