A Digital Record

Our cover story is about an archaeological application. Well-known geospatial services company Surdex1 was contracted by the Thomas Jefferson Foundation to acquire lidar of the Jefferson plantation in Monticello, Virginia. Not surprisingly, the new data has engendered many discoveries that were simply not possible with previous techniques. We’ve become accustomed to staggering discoveries through lidar’s penetration of vegetation, but it’s worth remembering that this need not be in tropical rainforest—the advantages bear fruit in temperate climes too. The authors mention the Cahokia site near St. Louis– there is a plethora of literature on this, including a useful, short piece on some surveying aspects2. I cite this as a reminder that there’s a lot more to archaeological surveys in the 21st century than photogrammetry and lidar: the Cahokia piece described a geophysical survey of the site, just as our Monticello piece concludes that the lidar data facilitates decision-making on the most promising places to conduct sediment analyses using a range of the latest techniques.

We are fortunate to share an article by Qassim Abdullah that is also running in Photogrammetric Engineering & Remote Sensing. This focuses on an aspect of Edition 2 of the ASPRS Positional Accuracy Standards for Digital Geospatial Data and emphasizes a self-evident truth: the ground control points and independent check points that we use to georeference then QC lidar surveys are themselves not perfect but are subject to errors, i.e. their coordinates in whatever datum is being used are not error-free and this has to be taken into account when estimating and publishing the accuracy of the lidar. Sometimes it’s hard to put numbers on the accuracy of the survey of the control and check points, but Qassim gives guidelines and typical values that can be used.

Crossing the Atlantic, we are pleased to offer an engaging article by Floryne Roche of the French national mapping agency, IGN, on the use of artificial intelligence to help with the processing of lidar data. France is heavily engaged on a nationwide lidar program, called HD Lidar, with similarities to the USGS 3DEP program, so the requirement for reliable, automated techniques to facilitate the massive data-processing task is an urgent one. IGN’s approach is both leading-edge and practical.

Contributing writer Al Karlin has provided yet another significant article. Lidar is being used all over the world to extract hydrographic and hydrologic features—stream geometries, hierarchies and so on. Al has looked at data sets of parts of Pinellas Country, Florida, to see how the results from QL1 and QL2 linear-mode lidar collections and a Geiger-mode collection compare. This is extremely valuable as it gives an idea of what it is reasonable to expect from the different modalities and sensors.

Brian Stevens’s piece describes the use of 3DEP and 3DHP by Woolpert to create the Ohio Surface Water Model, a new approach to elevation-derived hydrography. The testimonials from county engineers are heartfelt and encouraging.

Al Karlin has also played a role in the latest installment of Amar Nayegandhi’s “Full Coverage” column. These two experts argue the pros and cons of including total propagated uncertainty as lidar metadata. We should reflect on this as LAS, LAZ and other standards advance.

We end with a return to the rainforest—in Costa Rica! Andrew Kerr, from Hexagon’s R-evolution—crudely, the green part of the conglomerate—has been working on reforestation using tremendously informative forest data formed by merging airborne lidar from a Leica CountryMapper with ground-based lidar from the handheld BLK2GO. The images in this article are arresting in their intricacy and beauty.

You can learn more about Leica CountryMapper, both its capabilities and the intriguing history behind it, in one of our podcasts. The LIDAR Magazine Podcasts are growing as new episodes are added every couple of weeks3. Each is interesting in its own way, but the conversation with Ron Roth of Leica Geosystems, whom I’ve known for more than 25 years, is poignant.

I like to close editorials with snippets from something I’ve read. The National Trust is a UK non-profit that protects and manages coastline, woodlands, countryside and hundreds of historic buildings, gardens and precious collections, many of which were donated by families no longer able to maintain them. Reading a short article in the organization’s journal about an initiative to rejuvenate chalk grassland in the South Downs, part of southern England4, I learned that the Trust is working with Historic England on mapping the area’s many ancient monuments using aerial photography and lidar. Meanwhile, matters are more urgent in Scotland. At Knowe of Swandro, on the island of Rousay, which is in the Orkney archipelago to the north of the Scottish mainland, there are remains of important Iron Age and Norse settlements. Sadly, the sediments on which they are located are being washed away by rising sea level and more frequent storms, both occasioned by climate change5. The solution—use lidar and imagery to create a digital record for future generations, just in case the race against the elements is lost.

Reading and editing authors’ manuscripts and the resulting proofs is enjoyable yet challenging. But sometimes, while buried in docs/pdfs, one’s mind wanders. Almost two years ago, I became treasurer of the International Society for Photogrammetry and Remote Sensing (ISPRS6) at its XXIV Congress in Nice, France. I traveled west, on the fast TGV railroad, to Montpellier, to attend the YellowScan “LiDAR for Drone 2022” event. I reported this for readers7 and continued by train to Austria, for a morning in beautiful Graz at the facility of Vexcel Imaging. At that time, we knew Vexcel Imaging as a supplier of top-notch aerial cameras for crewed aircraft, but times have changed. Last year, Vexcel Imaging announced a new product, UltraCam Dragon 4.1, which is based on an integration of its UltraCam Osprey camera with RIEGL’s VQ-680 OEM lidar module8. Thus this firm is now fully in the lidar world—as opposed to supplying its big cameras to fly in the same aircraft as other suppliers’ lidar sensors—so I’m writing up the visit for an article to be published later this year.

I continued eastwards and spent one of the most perfect days of my professional life. Thanks to Johannes Riegl, Jr., of RIEGL USA in Winter Park, Florida, where I attended the opening of the new facility9, the folks at RIEGL’s headquarters in Horn, north of Vienna, rolled out the red carpet and gave me a day of intense, high-quality presentations intertwined with tours of the various buildings on the campus, and the new instrument test range, where I was honored to have Dr. Andreas Ullrich to accompany me!

I’m currently writing up travels that have taken place since Geo Week in Denver in February 2024—look out for them on the website soon. I believe it’s time, as one shivers in the winter of one’s career, to thank the people who helped me fashion my career, the magazine for supporting me, the conference organizers, and the magazine’s customers for their warm welcomes and unselfish sharing of technologies and ideas. Thanks for the memories.

1 Now part of Bowman Consulting Group: businesswire.com/news/home/20240402970569/en/Bowman-Enters-into-Definitive-Agreement-to-Acquire-Surdex-Corporation-Adding-High-Altitude-Digital-Imagery-Digital-Mapping-and-Advanced-Geospatial-Services
2 Thoresen, J., 2023. The Cahokia mounds, xyHt, 10(4): 10-14, April 2023.
3 lidarmag.com/podcast/
4 Beer, H., 2023. Changing Chalk, National Trust Magazine, 160: 32-27, autumn 2023.
5 Anon, 2024. In ruins: climate change is unearthing and erasing history all at once, The Economist, 450(9386): 74, 16 March 2024.
6 isprs.org
7 lidarmag.com/2022/06/24/nice-is-nice/
8 vexcel-imaging.com/the-new-ultracam-dragon-4-1-game-changing-hybrid-oblique-imaging-and-lidar-system/
9 lidarmag.com/2021/11/24/riegl-ribbon-cutting

About the Author

Dr. A. Stewart Walker

Stewart is the Managing Editor of the magazine. He holds MA, MScE and PhD degrees in geography and geomatics from the universities of Glasgow, New Brunswick and Bristol, and an MBA from Heriot-Watt. He is an ASPRS-certified photogrammetrist. More articles...