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Forteresse d’Oppede le Vieux

Elias Logan, BLK360, and Scanning 15,000 Years of History: Prehistoric Caves, Roman Ruins, and Medieval Chateaux in France

By Elias Logan


When we left off, the BLK360 and I had surveyed our way from the northern tip of Scotland to the southern shores of Great Britain. Now we invite you to follow us across the channel and onto the European mainland! In this post, we will return to the right side of the road (at the expense of my native tongue) as we explore France in pursuit of more scanning sites.  

Like its longtime royal rival, England, France’s architectural history extends back millennia, making for an extensive selection of stone structures in a state of ruin upon which the BLK360 could work its point cloud magic. So lace up your hiking boots and join me and my broken Francais on a ‘voyage touristique de recherche’ in the French countryside!  

BLK360 Takes On Dolmens and Romans; Chateaux too!  

With a landholding the size of Texas and just a month to take it in, I confined my roaming research to the country’s western and southern regions where I perceived the pithiest of France’s plentiful scan-worthy(1) sites to be. This whirlwind tour yielded enough scans and stories to fill up another half dozen blog posts, but I will restrain myself to the main sites and highlights:  

Both chronologically and geographically well-situated, the massive (both in size and scope) megalithic monuments of Brittany served as a starting point. Most renowned for its lengthy alignments of stone uprights, or menhirs, the megalithic concentration around Carnac also includes numerous dolmens – prehistoric compositions of uprights + capstones – and tumuli – similar constructs topped by mounds of earth or smaller stones.  

While the BLK360 and I scanned and sketched several of these monuments, perhaps most fascinating were those referred to as the Dolmens Mane Kerioned. This grouping of structures dating to around 3500 B.C. holds two apparent gallery-grave type dolmens some 20’ (6m) and a 90o turn from one another in a forest clearing bordering a highway. Ambulating – or scanning – about the clearing, one discovers a narrow staircase plunging into a third, subterranean stone chamber almost within the highway embankment! Inside are stone uprights similar to those above, but bearing unique rectangular and snaking line engravings decipherable with the aid of a flashlight as well as within the laser scan.  

Dolmens Mane Kerioned


From Carnac, I traced the Loire Valley - where the BLK360 captured still more dolmens situated in backyards (Dolmen de Bagneux) and vineyards (Dolmen de Curton) - before shifting south to the watershed of the Dordogne River. My initial – and most fruitful – stop was Périgueux, whose prominent 19th century Roman-esque cathedral is perhaps an homage to the city’s former life as the Gallo-Roman settlement of Vesunna. More direct evidence of this past remains in the form of an antique amphitheater, cylindrical temple, and domicile – several of which were the focus of BLK360 scans.  

Dolmen de Bagneux


The most ambitious scanning project to date, however, was a layered construct of Roman wall and gate ‘Porte Normande’ underpinning a medieval municipal building and fortress (aptly named ‘Chateau Barrière’ given its interior was barricaded to public entry). Over the course of a day, its 750’+ (230m) masonry circumference was captured in 75 setups by the BLK360.  

Chateau Barriere


Past Périgueux, I traced the Dordogne to the Vézère River where more medieval ruins mingle with some of the oldest known evidence of human settlement – painted cave and rock shelters dating to the Magdalenian period of over 15,000 years ago. While pre-dating by far the provenance of my study – in fact the idea of architecture altogether – these artistically augmented natural environments were nonetheless impactful in understanding the incredibly vast timescales of human and geologic history. So old, in fact, as to make my next grouping of scan sites appear relatively recent.

Continuing south, the scanner and I sought out the spectacularly sited, so-called Cathar Castles of the Languedoc. Perched atop precipices in the shadow of the Pyrenees mountains, from the valleys far below there was often little discerning where rocky cliffs ended and the stonework of these scattered strongholds began. Having climbed to these heights with the (fortunately compact) BLK360, however, joints and seams, vaults and beams gained resolution. At sites like Les Quatre Châteaux de Lastours where four individual castles dot the highpoints of a ridgeline, the BLK displayed its range by capturing a smattering of points belong to the neighboring keep separated by 160’ (50m) of sloping topography.  

Les Quatre Chateaux Lastours

Representation amid Reconstruction at Forteresse d'Odeppe le Vieux  

Just across the eastern border of the Languedoc in Provence, similarly dramatic slopes support the crumbling castle of Forteresse d'Odeppe le Vieux. Presiding over the medieval village of the same name, the former fortress is the focus of preservation and reconstruction efforts by a volunteer team led by Jean-Jacques Lohier. For a day in October that group extended to include myself, partner Emily Kruse, and the BLK360.  

After a tour of the site including some intimidating scaffold scrambling and ladder climbing, we set about scanning the exposed interior of the rectangular keep. The Forteresse team was also extremely hospitable in ensuring we partook in the customary lunch break of delicious breads, cheeses, cakes, and spirits! All not only necessary to fuel the team’s labor in stabilizing the castle’s towers and vaults but occasion for discussing – to the extent our broken versions of each other’s languages would allow – the work of partial reconstruction and significance of representation in that process.  

Forteresse d’Oppede le Vieux


Attesting to this fact, a set of floor plans drafted by another Harvard student some twenty years before that had guided work at the site in recent history. The scans produced on site now add to this representational continuum; augmenting, enhancing, even amending these resources for reconstruction.  

Forteresse d ‘Oppede le Vieux GIF and Plan

Elias Logan’s “3D” Scan Processing Practices  

To this end, it is worth sharing some of the ‘post-processing’ practices I utilized in creating representations of the rocks – in various forms – that composed the research.(2)  

  1. Define: My initial step in accessing and operating upon a compiled setup scan file in Leica’s Cyclone Register 360 PLUS software is determining and defining an exterior boundary of consideration. I prefer to allow the “natural” scope of the scanner’s range to suggest this shape, using the density of points to infer an area outside of which to exclude all others. Register 360 PLUS’s polygonal trim tool makes it easy to draw this bound and select ‘delete outside’ to remove extraneous data points.
  2. Delete: The trim tool in Register 360 PLUS also allows for easy ‘deleting inside’, a function that I subsequently use to remove traces of point-clouded humans (oftentimes myself caught in the scan) and objects from individual setups or the compiled scan. While arguably useful to show scale, occupation, or cultural context, because human figures are frequently in motion, they are usually only captured partially; making for more of a distracting than deliberate presence.  
  3. ‘Draw’: Where 3D scanning, and Register 360 PLUS in particular, is most revolutionary is in the creation of drawings based upon the captured data. A basic method of creating images is simply panning and zooming about the scan to settle upon views for export as image files. More compelling, particularly for professionals versed in orthographic projection (i.e. plan, section, and elevation drawings), is using the software’s TruSlicer view to cut vertically or horizontally through the captured information.  

Like the perspectival views described earlier, these images can be exported and, if desired, further processed into presentation imagery in programs like those of the Adobe Creative Suite. I have also been creating short stop motion videos using still images compiled into GIFs and more smooth flowing animations using screen recording programs (assisted by Leica’s Andy Fontana). The opportunities for output truly extend to the limits of the imagination and experimentation!  

While I continue to explore these computational paths, so will we continue to explore the European continent with the BLK360. As the temperatures drop, so too will our latitude; extending the field season thanks to the mild Mediterranean climate. The next post will see the BLK360’s laser focus shift to the unique architectural remains of two distinct prehistoric island cultures; the Nuraghic civilization(s) of Sardinia and temple-builders of Malta. Beyond the structures themselves, accompanying artifacts referring to these fortresses and temples expand the dialogue about the role of representation in my native field, that of architectural design. Surely fascinating finds and conversations lie ahead. Until my next post, ci vediamo!    

1 See my ‘4-C scanning criteria’ in an earlier post on Scotland: https://shop.leica-geosystems.com/blog/scanning-scottish-cairns-and-castles-elias-logan-and-blk360-round-2

2 For a more complete instructional-type survey of the software tools, particularly Leica’s Cyclone Register 360 PLUS, I would refer readers to Leica’s video tutorials here: https://leica-geosystems.com/en-us/products/laser-scanners/software/lei…