Do you have a burial mound or some other kind of archaeological features, lots of them have been plowed over for decades or over 100 years in some case. So now there might not be much left of that. Now some of those features might only stick up above the surrounding surface by 10, or 20 centimeters. And that can be really difficult to see just with your eye when you're on the ground. But an elevation model we make from the drone data can pick up those sorts of features and reveal stuff that's really difficult to see otherwise.
For centuries, the tedium of archaeology has often been about digging in the dirt. But now in the digital age, archaeologists are using more diverse tools to learn about history's past. This is random acts of knowledge presented by Heartland Community College, I'm your host, Steve fast. Today, we're talking about how some archaeologists are taking to the skies to learn more about field sites that are hundreds, if not 1000s, of years old, aerial photography, and photogrammetry are changing the fields of archaeology. And today we'll learn about how
I'm John Lambert, I'm an archaeological Spatial Analyst with the Illinois State Archaeological Survey, or just I SAS usually, for short. We're part of the prairie Research Institute at the University of Illinois, we're, you know, kind of one of a number of state surveys that are part of PRI, so we're kind of comparable to like the state Geologic Survey, the State Water Survey. So kind of our piece of that we document and research and help prevent impacts to the archaeological record within the context of development in the state. So we work with kind of a number of different state agencies, you know, one of our main contacts is i dot the State Department of Transportation. So we do a lot of archaeology that kind of lays the groundwork for IDOT projects. So think, survey and excavation and documentation before, say, like a highway project. Preferably we, you know, make recommendations to say an agency like Ida that would avoid impacts to the record in the first place. You know, if that's not possible, then we'll go in and we'll activate things, we'll document collections, all the archaeological material gets analyzed, and we publish reports, the stuff gets curated. But that's kind of the gist of it. I
know that you've been using drones in surveying some of these sites. And I would think that that would tie into some of the work that surveyors do, for instance, I doubt they're gonna put a new road somewhere, they've got a survey that land, they've got to figure out what some of that impact would be. Are these the same kind of tools you use?
Yeah, absolutely. I mean, we use the drone, you know, to actually useful for a whole bunch of different stuff or relating to archaeological projects. But part of is that kind of baseline, you know, we'll use the drone to go fly aerial photography, or photogrammetry. To get really high quality elevation data, we use that for a bunch of stuff. I mean, part of it is just getting a sense of how an archaeological site fits into the surrounding landscape, or documenting archaeological features at a site that we may already know about, or trying to find new features that maybe we suspect or there we think might be present. Things like burial mounds that have some expression on the surface, but might be really hard to see from the ground. So the drone is really great for that kind of stuff.
You mentioned photogrammetry explain for people that are completely coming from outside of this, what that means what is photogrammetry.
So kind of like a really basic level of photogrammetry is just using information from overlapping images to take measurements of something. So kind of the easiest comparison, it works really similarly to how your depth perception works with your eyes. So your eyes see two overlapping images of the world. And they vary a little bit since your eyes are, you know, different locations and your brain uses that. It uses the differences between those overlapping images to figure out how far away is an object from you. So essentially, we're doing the same thing with the drone. It's just dozens or hundreds of overlapping images instead of two. So we fly usually some sort of automated flight route that zigzags across an area and we design it so it has the right amount of overlap between images and we use that to kind of make a surface model of the area.
So when you're doing that, you mentioned that the difference as you're getting down At a 3d image, when you see differences in height and differences in how something looks from a distance can be revealing, and I know that some of the sites you've covered had been burial mounds. How is this process helped you figure out things about burial mounds?
So that's a really good question. You know, one of the ways of the drone is really useful for that kind of thing. The amount of detail that you can get recording the ground surface with the drone is, it's a really high level of detail compared to other datasets that we have available. So think about, like traditional aerial photography or elevation data from, you know, older data sets, or even more modern stuff like LiDAR, it's not as high resolution as the stuff we can produce with the drone. So if you have a burial mound, or some other kind of archaeological feature that lots of them have been plowed over for decades, or over 100 years, in some cases. So now there might not be much left of that, you know, some of those features might only stick up above the surrounding surface by 10, or 20 centimeters. And that can be really difficult to see just with your eye when you're on the ground. But an elevation model we make from the drone data can pick up those sorts of features and reveal stuff that's really difficult to see otherwise.
When you talk about the modeling and the technology, how long have you been using drones in the field for these purposes?
I SAS got our drone a little over a year ago, it was last spring.
So really, this is relatively new, a new process you've been using? Yeah. What sort of technology is on the drone? What all are you using? What does it take? Is it something that is a fairly simple set of tools that you have that you can fly over there? Or is it anything of this sounds pretty high tech, but how developed? Is it? Is this something somebody could just go out and put together this package easily? Or is it something that really is a big investment for the survey?
No, I mean, that's one of the things that's really great about it. I mean, we did the drone we have it's a phantom four Pro from DJI, it's kind of like a higher end consumer grade drone, but it's not some outrageously expensive industrial drone, you know, as far as capturing the photogrammetry data basically just has a really nice camera that takes high resolution photos, and it has a gimbal that, you know, the really good image stabilizer. But other than that, it's just photography. So it's not a complicated setup, it's not really expensive. It lets us get this high quality data for pretty cheap. And also basically, whenever we need it, there's not much lead time we can go out and fly a site whenever we need to.
So do you have to file a flight plan ahead of time for potential use in that site? Or is it something where that fits into the general parameters of what you're already doing there?
So it depends on where you are, that's always something that we have to be aware of. There are areas that are FAA controlled airspace, generally, that's within five miles of towered airports. So if we're in one of those areas, yeah, we'll request a waiver from the FAA beforehand, there are actually mechanisms that are built into the drone software now that it won't let you take off, if you're within one of those controlled airspace areas until you actually like unlock that area in the drone software to to kind of a few layers of protection that are built in now. But most areas we fly typically aren't controlled airspace, usually, we're out in agricultural fields or, you know, areas that aren't very densely populated that they typically aren't controlled airspace. So it just kind of depends. It's just part of the planning process for getting ready for projects.
When you talk about programming, the drone, I've heard this referred to by others, for other purposes for serving is basically just kind of program it. And it's sort of like a lawn mower, it just goes up there on a pre determined pattern and just goes back and forth and back and forth and covers all this area. Is that about how it works?
Yeah, actually, that's a really good analogy. So we have flight planning software that we use, and we basically just tell it that I want my pixel size and the images to represent a certain area of ground surface. So if I so that will kind of determine your altitude. If you're closer or further from the ground, your pictures represent more or less area. And then you also tell the software how much do I want my photos to overlap? And usually it's 60% side decide between images and 80% front to back, and then the software does the rest it lays out out a grid, and you upload the route to your drone and pretty much press go and it flies it.
So when you get this data back, how long does it take to kind of process it and look at it and see what you have,
actually the processing the data takes longer than collecting it. So we're usually using software called our GIS. It has a set of photogrammetry and image processing tools within it. So we'll do thing it does things like so your images will have GPS coordinates embedded in the information for the image. So it kind of does a rough plot of where all the images should land. And then it refines that alignment based on you know, kind of overlapping information in the images. And we also use, I should have mentioned this before, I guess it will also lay out Ground Control targets in the area where we're gonna fly. And so the drone will capture those in the imagery. And then we also GPS those locations with a really high quality GPS unit. And so that's also used to kind of refine the alignment and the location of your photos. But so yeah, you use that ArcGIS software, also to make your elevation model to make, you know, kind of a composite mosaic of the aerial imagery, and you know, kind of a few other products that you might want.
So once you have all this data, and you've gotten the map, so to speak, what work then starts happening on the ground, how does that aerial data, inform what you need to do physically on the site, because you can't just use the drones to learn the things you need to know.
Sure. I mean, that's a really important point where, you know, say we detect a feature, say, we fly the drone, we get our elevation model. And we see a feature that looks like it might be prehistoric mound. So that's always something that we have to go out and groundtruth in person. So that slight rise and typography that might be something totally natural, might be something somebody created 1000 years ago, or it could be something where somebody pushed up a mound of dirt 50 years ago. So that's always something where the drone is really good at helping us identify like potential features, or helping confirm things we already knew about. But it's not a replacement for survey or excavation, you know, in person. So we'll use that information we get from the drone to help our field crews, you know, plan projects and know what things to be aware of, you know, we also just use it to like, do really basic things like take photography and video of, you know, excavation unit, it's just part of how we document and publicize projects. So it doesn't just have to be photogrammetry. You know, it's also just really nice for that kind of thing to
when you're doing that does it make it faster than if you were to ground survey at first. Some of
that will just depend on schedules for individual projects, whether we can get out and fly before survey needs to be done. Usually, the drone flights will kind of be done in conjunction with survey, because when we go out and we do ground survey, we're also you know, looking for artifacts or archaeological features that the drone wouldn't necessarily be able to see. So they kind of they complement each other, but neither one kind of replaces the other.
So let's talk about a couple of these other sites where you've used the drone technology, we briefly referred earlier to some burial mounds, and I know that that's one site that you did explore, but tell us about some of the other ones. So at this point,
we've probably we've flown the drone and maybe half a dozen sites or so, you know, all of them are within Illinois. And they actually range they kind of run the gamut as far as prehistoric sites in Illinois go. I mean, we flew, the oldest site we've flown is actually in southwest Illinois. It was about a 10,000 year old site, actually where we've got some pretty like very cool intact archaeological deposits. We have things like the oldest Turkey wing bone call that's ever been documented in the world, the oldest intentional dog burial in North America. And so we flew the drone there to kind of document the site setting and the landform that that site is part of and they get really good photography and stuff like that. Most of the stuff we've flown the drone at have been more recent, they've been sites they date to a time period that archaeologists called the Mississippian period. It's kind of from about, say 1800 years ago, somewhere in that range. And those actually are places where we might expect to see features that are still on the surface. One of the kind of interesting things about the Mississippian period Is they did a ton of landscape modification. So not just building mounds, but also like creating borrow pits and leveling areas out and creating raise pathways and areas that are, you know, wet or swampy. And so that's something that we've done at a number of sites. We've flown sites and I know McLean County, Peoria County, I believe, and like St. Clair County, kind of all over the state, and site, those more recent sort of sites where we might actually still see things on the surface.
So when you're dealing with one of the sites like the first one you mentioned, that's so old. First of all, where is that? And how does it get identified in the first place? Is it something where there's an idea that that's might have were been you looking for it? Or does somebody find something on the ground? How did you identify that site in the first place?
So yeah, that's a good question. That's always kind of one of the I don't know that off is often kind of a misperception about archaeology that we just, you know, happen to stumble upon sites, or we get lucky and find things. I mean, I'm not saying that doesn't happen. It definitely does. I
think that makes the news, when that happens, somebody's digging a parking garage or something, and they find something, but it's
kind of a mix. So yes, some of it are those sort of fortuitous, accidental discoveries that happened during other kinds of construction. Other times, we have a really good idea of where things are, usually, we're working with geologists, or soil scientists, and will have a pretty good idea of, you know, if we do construction in this area, how old do we expect, essentially, how old do we think the dirt is, and that'll give us a good idea of whether we should expect to find certain kinds of archaeology, you know, we take into account how much erosion has there been during certain time periods, how good is that soil for organic preservation, you know, things like that. So usually, we have a pretty good guess. We're also using the location of like previously recorded sides, you know, things of that nature. And then that's why we always go out and do survey, you know, we have guesses, but we always have to go out and actually look in person. So lots of sites get found during survey, but that one site in particular, that 10,000 year old site actually got found, I think it was actually during construction of a ditch on the side of basically this small county, gravel County Road, they just accidentally dug into the side of this site. So that kind of thing does happen. So when
you find something like that, does the drone technology then help you figure out how large that site might be? Is there anything that you can employ the drones for early on when you're just discovering a site?
So that 10,000 year old site belongs to this time period, we call the early archaic, so that early archaic site was found on this colluvial fans, you had sediment that was coming down, and this little break and a bluff line. So really accurately mapping where that soil was deposited would give you a pretty good idea of where can we potentially have archeology of that age. And then other things that actually have a surface expression. So nouns or I just keep using that as the example. But it could be, you know, historic features. So things like building foundations or things like that. Documenting additional features would also give you an idea of how far aside extends,
are there any tools that you see that are being developed that might help you get even more data through the aerial information gathering?
Yeah, absolutely. I mean, photography is just one tool, and it's one of the ones that's been around longer. But Lidar is actually just being deployed on drones now. So LIDAR uses a laser that sweeps back and forth across an area and uses how long it takes for that laser to return to measure elevation. And it's only really recently that LIDAR units are even small enough to fit on a drone. It's still really cost prohibitive. It's really expensive to put LIDAR on a drone right now. But that's coming, the price is going to come down. There are also things like thermal imaging, so depending on what's you know, what might be buried in an area, certain kinds of features, retain or dissipate heat faster or slower, and you can actually pick those things up with thermal imaging. So there's thermal imaging on drones. And then there's also something called multispectral imaging that it's actually just photography, but it collects imagery in these really specific wavelengths of light. And you can use that to measure things like say how well vegetation is growing, so whether it's something like coal Orion is healthier or not. And it doesn't sound like that has a lot to do with archaeology. But it kind of works on the same principle as thermal imaging where depending on what's buried somewhere, it will either retain moisture, or it will be drier or wetter, depending on if you have something buried like a pit feature or a wall. And that will affect the growth of crops. And we can actually pick those features up from the air with multispectral imaging. So those are a few of the other things that are out there and stuff we're like really actively looking into right now.
So when do you anticipate that you'll be able to use some more of those tools with the Illinois State Archaeological Survey,
probably multispectral imaging will be the next one that we get into of the three that I mentioned of thermal imaging, multispectral and LiDAR, it's multispectral imaging is the most affordable, there are units out there that we can actually mount on the drone we already have. So that's a huge plus. And it's a nice, it would be a very nice complement to the photogrammetry. So the photogrammetry, you're measuring the surface of an area multispectral imaging, you're kind of using those differences and plant growth to get a peek below the surface. So they kind of go together and tell us different things about a site.
So even though drones, you said you've just been using them for just a little over a year in your studies, but aerial photography and other technology, this isn't new to archaeological study, it seems like the tools as soon as they are available, archaeologists start using them. Yeah,
I mean, that's actually something that archaeology is really good at, we're really enthusiastic borrowers of technology from other disciplines. And actually, believe it or not, the first aerial photography of an archaeological site took place in Illinois, just after the end of World War One, you had the first you know, reliable, accessible airplanes. And Cahokia is a huge archaeological site just outside St. Louis in Illinois. And people flew aerial photography of Cahokia in the 20s, to map out things like mountains and borrow pits, and you know, other sorts of like big scale landscape modification people did there about 800 to 1000 years ago. So we've used aerial photography for a long time to try and locate sites to try and document sites we already know about, even to do things like map soil units that might correspond with certain kinds of archaeology. But the fact that we can go out and fly a site, whenever we need do with a drone for kind of a one time really small investment, instead of paying for a plane to get up in the air and do a custom flight plan. Yeah, I mean, that's huge. That's really, really nice for us, or even just something really basic, like I can fly 50 or 100 feet above a site and get fantastic images of excavations, where before that kind of stuff was really hard. You know, you'd have somebody with a giant pole with a camera on and trying to take a picture of things or, you know, doing things like stacking ladders on top of each other, you know, just really crazy stuff. So the drone just makes all that so much
easier. Well, this sounds a lot less dangerous as well. Yeah, you
don't have to get anybody up on a ladder with a rope tied around them and people holding the ladder up.
Well, John, thanks so much for taking some time to talk about this cool work that you're doing.
You know, a lot of these methods aren't just applicable to archaeology, so anybody that might be monitoring landforms, or topography or stuff like that photogrammetry could be a good way to go.
John Lambert is an archaeological Spatial Analyst at the University of Illinois Champaign. He works for the Illinois State Archaeological Survey and as a speaker at the drones in the heartland conference held on the campus of Heartland Community College in October. If you'd like to hear other interviews about technology, history, the arts, wellness and more, check out our other random acts of knowledge podcasts, subscribe on iTunes, Spotify, or audio boom. Thanks for listening
