Last updated: July 20, 2023
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Podcast 047: Recording Civil War Earthwork Fortifications with LiDAR
National Park Service
LiDAR & Fortifications
Ben Donnan: Hey Matt How is it going?
Matthew Luke: Its going pretty good. Ben Donnan: If you would please tell us about what kinds of projects you have been involved with at the trust and what are your current projects?
Matthew Luke: Currently we are working on recording Civil War earthwork fortifications and Revolutionary War fortifications using 3D ground-based LiDAR scanners and also developing augmented reality apps to interpret the data we are collecting to the public.
Augmented Reality & Preservation
Ben Donnan: Cool. So what is augmented reality and how is it used to preserve a site?
Matthew Luke: Well augmented reality is basically adding three dimensional or 2D objects such as 3D models of forts or 2D images, maybe historic sketch of the fort or engineering drawings and video content and audio content to the real world.
Matthew Luke: So basically when you are on a site and you watch the app and move around with your smart phone you actually be able to see the content related to that site. So as far is it being used as a preservation method I would say it has more of an impact on preservation as in getting the public back involved with preservation and interested in preservation there for supporting the preservation as far as the public side of it.
Ben Donnan: So you guys are heavily focused on encouraging the public to be involved with these sites, now you mentioned ground-based laser scanning and LiDAR, how do you guys use that in terms of geospatial datasets and the process where you would go through collecting the data and then processing it? How does that work?
Matthew Luke: So basically we have Leica C10 Laser scanner that we are using from Georgia Southern University and what we are doing is going out and recording 3D topographic data these fortifications these earthwork fortifications. And how that works is that sensor sits on a tripod and fires a beam of light and measures the time it takes for the light to reflect back to get the distance therefore recording a survey similar to a total station but without the reflector.
Matthew Luke: So this machine actually collects thousands of these points these measurements per second and this data can be used then to generate 3d models of the ground surface with all the vegetation removed giving us a better overview of the site and how the different features of the fort relate to each to one another.
Matthew Luke: And as far as public interpretation we use these models and augmented reality but the data can also be used for monitor sites and managing the site as far as erosion that may occur over the years we can scan the sites and go back in a year and scan them again and measure erosion as far as road beds that have been cut through or any kind modern features that are impacting the sites or concerns as far as erosion. It also preserves the site digitally as it appeared on the day of the scan. So there is always high resolution three dimensional survey of the site digitally preserved so in the future we can go back and if anything happens to the site we can go back and see how it looked on that day.
Ben Donnan: So do feel using this data and inputting it into AR so people could see it, do you think this is one of those methods that should be added to a modern toolkit for preservationist or person involved in historic preservation?
Accessible Reporting
Matthew Luke: Yes, and I think that we have had a somewhat of a disconnect with how we interpret our data and findings to the general public. We may find site reports and technical reports interesting and journal articles interesting but the general public as far as that type of information being consumed by the general public it usually does not go over to well.
Matthew Luke: And also we have been interpreting sites primarily with text based signage or text and image based signage which as I have been scanning sites I watch visitors come to site look at the sign they don’t really read any of it look around kind of wonder what happened here and walk off. So with the increase use of smart phones and tablet pc, you know a device that essentially everyone has now.
Ben Donnan: A mobile device?
Matthew Luke: A mobile device yeah. We have decide that, that will be a way to reach the general public on a device that they are familiar with, familiar using would be with the augmented reality.
Ben Donnan: So a lot of this work is stemming from your master’s thesis work. Can you tell me a little bit about it? A little bit more specific detail about it.
Matthew Luke: Well we have been collecting data for the last four years now, on various earthwork fortifications related to the Civil War on James Island in SC. We have compared the number of known sites with the number of sites visible using freely available aerial LiDAR data and the size of the features to kind of gage how well freely available data performs for prospecting and locating sites.
Matthew Luke: We have been using the ground-based laser scanner to assess the erosion that has occur on the sites since their construction to the present day to get a general estimate on erosion rates into the far future and to better manage the sites. And we are taking the LiDAR data and actually comparing profile slices of the parapets and other features related to the fortifications to contemporary engineering drawings of the fortifications.
Aerial & Terrestrial LiDAR
Ben Donnan: Now I know from working with you before I know that you have been working on trying to integrate the aerial LiDAR with terrestrial LiDAR and how would that work and has it been effective has it been good for use in augmented reality?
Matthew Luke: Well we have been trying integrate and we have successfully integrated several datasets that we have collected from James Island with the freely available aerial LiDAR that was shot for flood plain mapping and as far as the results we have gotten pretty good accuracy and that has occurred by picking out landmarks, such as street corners drive ways etc. houses, and conducting high resolution scans in those areas and then overlapping that data and georeferencing it to the aerial based data.
Matthew Luke: And what this does is the aerial based data actually gives a much better picture of the landscape and how the sites relate to the landscape and the area as a whole while the ground base data gives the high definition and detail of the actual features still presence at the site so it kind of gives a micro and macro view of the site.
Interpretation & Visitor Technology
Ben Donnan: Before concluding is there anything else you can think of or would like to add to anything we have discussed?
Matthew Luke: I would just like to say that you know I believe getting the public involved in and interested in these sites is key to preservation and I think that we often over look. Without public interest and public involvement with these sites there’s no funding there’s regulation to preserve these sites. So you know anything, I think we need to step up our interpretive sides of historic preservation.
Ben Donnan: And additionally, do you feel augmented reality could be one of those solution?
Matthew Luke: Yeah and augmented reality is definitely one of those solutions. You know it is format that devices format that everyone is familiar with that is widely used every day. If you walk on a college campus or you are walking down the street, you will see numerous people texting checking their email surfing the web.
Matthew Luke: So it is a device that the public is very familiar with and that they use every day and if we can present or if we can reach them through this device I believe it will be a very effective means of interpreting a site and getting our interpretations of sites up to par.
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