Written by Will Gunn

LiDAR (Light Detection and Ranging) is a technology from the 1960s, which can create detailed 3-dimensional maps of surfaces and objects. A LiDAR device emits thousands of laser pulses per second towards a surface or object from a singular source. The laser pulses hit the surface and reflect back to the LiDAR sensor. The system calculates the distance between the sensor and the surface at thousands of points. As the laser sweeps across the surface, the system collects millions of distance measurements. These are compiled into a 3-dimensional map that represents the surface in high detail. Initially the US military and NASA developed the technology to help with the moon landings. Currently this technology has a plethora of uses, but I will be focusing on laser cliff mapping and its potential benefits.

LiDAR has several advantages over more traditional methods of cliff mapping. LiDAR can produce replicas of a surface with an extreme precision – down to millimetres. Obstacles that earlier technologies (such as optical sensors) would have fallen short at, such as thick vegetation or limited light, are not an issue for LiDAR technology. I would argue that the main advancement made by LiDAR technology is the speed of data collection, the fastest being able to capture 976,000 data point a second. These highly accurate replicas of cliff surfaces can by analysed and used to predict potential rockfalls or mass movements. When a potential hazard is detected nearby a large population centre, local authorities can be informed. They can then use this information to employ a variety of mitigation strategies, for example nets to catch loose debris or large pins into the rock surface to provide internal stability.

La Jolla is a densely populated population centre, with significant tourism infrastructure at the base of several cliffs. These cliffs are constantly being chemically weathered due to the high moisture content in coastal air. This elevated risk of rockfall means the infrastructure is in imminent danger. LiDAR technology has tracked the evolution of the cliff face over several previous collapses, allowing for areas of future concern to be isolated. With this information several footpaths have been closed and netting installed to protect buildings and public areas, potentially saving lives. The island of Capri is an Italian tourist destination and another example of lots of restaurants, hotels and homes located near steep cliffs. LiDAR technology was used to detect cracks in the rock face and suggest the most impactful location for netting is.

Aside from cliff measuring and recording, LiDAR has many other modern-day uses. LiDAR is used in self-driving cars to detect obstacles, map the surroundings, and help the vehicle navigate safely by creating real-time 3D maps. LiDAR helps archaeologists detect and map hidden structures, such as ancient ruins or landscapes, under dense vegetation or soil without disturbing the site. LiDAR can be used to measure particles, clouds, and pollution levels in the atmosphere, helping scientists better understand weather patterns.

One drawback of this exciting technology is the attached price tag. While it is ‘only’ around £1,000 for the LiDAR technology found in automated vehicles, the models used to map cliff surfaces with sufficient detail cost between £30,000 – £150,000. This of-course represents a significant drawback, and it remains as the only thing preventing the technology from being used globally to drastically reduce death figures from natural slope-based hazards,