LiDAR mapping is a powerful tool for creating detailed, 3D maps of the Earth’s surface. How does it work, what is it used for, and what are its limitations?
Key takeaways:
- LiDAR mapping uses laser scanners to help create a 3D image of the Earth’s surface
- When combined with other geospatial technologies, it can help build incredibly detailed 3D models
- Learn how LiDAR mapping works and what it’s used for
- Find out about limitations of LiDAR maps, and how they can be overcome
There are many ways of collecting data to create maps today – from satellites to aerial photogrammetry to ground surveys. In general, however, these techniques only produce 2D maps. While there are sophisticated techniques available that can transform these maps into 3D models, the source data remains in two dimensions.
However, Light Detection and Ranging (LiDAR) offers us a powerful way of collecting data about the Earth’s surface in 3D. That gives us unparalleled accuracy when we want to create maps of a specific place and analyze what is there.
Since the 1960s, people have used LiDAR systems for mapping purposes. Let’s learn more about LiDAR mapping, why it’s useful, and how it can be combined with other geospatial techniques.
How does LiDAR mapping work?
LiDAR mapping is a form of remote sensing that uses laser technology to build a 3D map of the planet’s surface. Typically, LiDAR surveys are conducted using airplanes, but they can also be done with helicopters, satellites, or even drones.
Here’s how LiDAR mapping works:
- An airplane mounted with LiDAR sensors flies over the area of interest
- A LiDAR laser scanner sweeps over the ground below
- It sends light pulses toward the ground surface and then measures how long it takes for each pulse to reflect back
- By calculating how long it takes for the light to reflect back, a computer can calculate the distance to the surface that the laser reflected off
- This helps to create point cloud data, which helps to produce a 3D model of the Earth’s surface and things on it.
LiDAR mapping offers a major advantage. It creates Digital Terrain Models (DTM) covering the Earth’s surface. It also produces Digital Elevation Models (DEM), known as ‘bare earth’ models.
Learn more: What is a Digital Surface Model?
Each time the laser scanner sends out a pulse, light reflects back multiple times from different surfaces, and this can give us data to create a DTM and a DEM. For example, if the airplane is flying over a tree, the first light to reflect back will bounce off the top of a tree (telling us its height). But, some of the laser pulse will pass through gaps in tree gown to the ground, and bounce back milliseconds later. This second data point tells us about the shape of the ‘bare earth’.
For more information about how LiDAR mapping works, watch this simple but helpful video by the US National Ecological Observatory Network.
Which industries are using LiDAR mapping?
LiDAR maps create highly detailed 3D maps of the Earth’s surface, and professionals in a variety of industries are using them for different reasons.
- Simulations and training
Companies that build simulation platforms may use LiDAR maps to help build out 3D models of real world places. For example, a company that builds virtual military training environments could use LiDAR data to create training scenarios that feel more authentic.
- Telecoms
Accurate distance measurements are very important in the telecoms industry, especially for radio frequency planning where engineers are looking to identify obstacles that could attenuate signals. LiDAR creates a detailed picture of the ground and its contents. It aids in planning cell tower placements and other devices.
- Conservation and forestry
LiDAR mapping is very helpful for the forestry industry and nature conservation. Conducting LiDAR surveys can help monitor the health of forests, estimate the density of trees, and even give an estimate of how much undergrowth is present.
- Engineering and infrastructure
Engineers can benefit from LiDAR surveys in multiple ways, as it can help them better understand the bare earth. For example, when planning the route for a road, LiDAR can help identify faults in the ground that may not be visible from satellite images due to tree cover.
- Insurance
LiDAR maps can be very useful when identifying potential risks for insurers. It can reveal historical landslides, floodplains, and other risks that might not be visible from the ground or space.
- Disaster planning
Emergency services and governments can use LiDAR maps to support emergency planning. The technology can help identify places that would most likely be affected by tsunamis, landslides, floods, and other natural disasters.
- City models
Urban planners can use LiDAR to help build up 3D models of towns and cities, showing both the bare earth plus buildings, vegetation, rivers, and more. This can be used to feed into digital twins too.
- Archaeology
LiDAR has been used by archaeologists to make fascinating discoveries about the past. For example, it has been used to find overgrown ancient settlements that have disappeared into the forest. In the United States, LiDAR was used to identify a prehistoric landslide that occurred after an earthquake around 900 AD. Native American oral history referenced the earthquake, and LiDAR mapping clearly revealed its location, even amidst the dense trees that otherwise hid it.
Limitations of LiDAR mapping
As of 2023, it is believed that only 5% of the planet has been mapped using LiDAR systems. Although LiDAR maps are incredibly useful, collecting the data is time-consuming and expensive. Building a LiDAR map of one region would cost millions of dollars and take several years to complete.
LiDAR mapping is also extremely resource-intensive. It requires pilots, expensive equipment, advanced software, and skilled technicians to capture the information and turn the point cloud data into something useful.
What is more, LiDAR can quickly go out of date. If land use or land cover changes, then the information from the maps quickly becomes irrelevant.
Combining LiDAR maps with other GIS layers
LiDAR maps are a powerful technology that can offer unprecedented detail about our planet. However, it has limitations. It’s best used with other mapping technologies in a GIS. When organizations have access to point cloud data, this can be layered over existing GIS maps, and ‘fuzed’ to give users a 3D model of the environment they’re interested in.
For example, one can combine a satellite image of a village with LiDAR data. The satellite image reveals colors and textures of buildings, walls, trees, and roofs. The LiDAR data offers height and depth insights. Together, they let us create a realistic 3D model of the settlement.
At LuxCarta, our technology incorporates LiDAR data. This enhances our 3D models with more detail and perspective.
Creating 3D models even without LiDAR mapping
LiDAR mapping is helping cartographers and specialists worldwide to create maps of the planet in unprecedented detail. When the data is accessible, it offers a compelling method for investigating what is happening on the ground and building 3D models.
But it’s not the only way of creating 3D models. At Luxcarta, we have developed an accurate and efficient methodology for automatically extracting footprints of buildings and vegetation based purely on satellite imagery, then using shadows to calculate height and depth of objects on the surface. You can use this information to rapidly build 3D models in a very short space of time without needing any additional equipment. Our solution provides the three dimensions provided by LiDAR maps, but at a far lower cost.
To learn how we can combine LiDAR data into our maps – or to find out how we can build 3D models without LiDAR – contact us today.
