Lidars come into play. How laser scanning saves monuments from war, the elements and time

It is not necessary to count on the fact that Russia will stop destroying historical objects. If the enemy army does not aim at residential buildings, then it aims at cathedrals and museums. How to protect them from disappearing without a trace and reproduce them in their original form, if necessary? Opinion.

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What is laser scanning and how it saves history

A decade ago, laser scanning technology might have seemed like something out of a sci-fi movie. Previously, researchers had to remove plaster casts from monuments or make papier-mâché to get a life-size model. But today there is already a tool that allows you to study objects of any size without touching the original at all. To do this, three main types of scanners are used: high-precision metrological scanners (hand-held scanning), scanners on tripods (ground-based scanning) or aircraft: drones, helicopters, aircraft (airborne scanning) equipped with lasers – lidars. All of them provide scanning of the internal and external elements of the structure with a level of accuracy that was previously impossible or time consuming.

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Briefly about this technology can be described as follows: a laser directs a beam of light into a wall, measures the time it takes for it to reflect from the surface, and creates a point in space. During operation, the laser produces millions of such “shots”, each of which provides information. This forms a point cloud that visually resembles a 3D digital model. In the future, it is used to design and create drawings and realistic three-dimensional models. The image can be stored in digital space and used by both scientists and architects during restoration work.
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Recently, developers of smartphones and mobile applications have started talking about 3D scanning technology. The latest iPhone models have lidar sensors. Currently, they are used to create better photos and apply AR effects, but later the company may take a step further and start using the technology for other purposes. However, the scanners in phones do not have the accuracy needed for design.

The war prompted ordinary Ukrainians to look for solutions that contribute to victory. This is how the Don’t Home project appeared, which helps to record crimes and shows how Ukrainian cities look like as a result of shelling and airstrikes. But the project doesn’t let you see the full scale of the destruction, as it offers panoramic photos instead of detailed digital models. Such photographs are almost impossible to use for reconstruction.

World Experience: From Notre Dame to Babylon

When the flames engulfed the roof of the famous Parisian cathedral, the whole world watched in horror as the destruction of the pearl of French Gothic architecture. But there were those who knew that Notre Dame would be restored thanks to a 3D model created on the basis of laser scanning. It was held for future restorations half a decade ago by art historian Andrew Tellon. To obtain a point cloud, more than 50 scans were performed in different places of the cathedral, as a result of which a detailed digital model was created. Perhaps it is this scan that will play a decisive role in the revival of Notre Dame.

Tellon is not the only one who has contributed to saving ancient objects. Hundreds of companies and non-profit organizations are trying to preserve the attractions at least in digital form. Among them is the CyArk organization, which has captured more than 200 cultural heritage sites on all continents in almost 20 years of work. Countries and international communities are asking organizations such as CyArk to preserve their historic buildings and landmarks. So, in 2009, the World Monuments Fund (WMF) offered to scan the Ishtar Gate and Nabu Sha Hari Temple in Babylon to document their condition.
How laser scanning will help preserve Ukrainian history

Saving sights from the elements and the passage of time is one thing, and saving them from war is quite another. Almost every day in Ukraine, its cultural and historical heritage is destroyed. The Ministry of Culture and Information Policy has created a special resource where you can send photos and videos of destroyed sights. These pictures can be evidence in court, but will do little to help with recovery. The method of reconstruction from old photos and sketches was relevant until the advent of the latest technology. Now lidars come into play.
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Laser scanning is the fastest and safest way to preserve World Heritage sites for future generations. Lidars read objects in a matter of minutes, and thanks to drones, it is possible to scan those areas where mine clearance is still ongoing. These digital copies will exist for a long time after the disappearance of the originals, and for architects they will become an important information basis for restoration.

First of all, you should scan the sights that are not yet damaged. They can be studied both from the inside and outside. By studying the object, lidars receive millions of data, in particular, about the exact size and texture, which will allow the structure to be reproduced in all details if it is damaged. The second stage is the scanning of partially damaged sights. It will help determine which elements can be saved and which are completely destroyed. In addition, scanners make it possible to study objects from a distance, without having to go into destroyed rooms, as this can be dangerous, and drones can scan from the air.

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