what is lidar?
A guide to Light Detection and Ranging.
LiDAR is a remote sensing technology that uses rapid laser pulses to map out the shape of the earth and its surface characteristics.
These precise measurements can then be used to create 3D models and maps of objects and environments.
Pairing a LiDAR scanner with a drone makes LiDAR more accessible, and allows surveyors and other iprofessionals to collect precise data, quickly, efficiently, and safely.
As a result, LiDAR sensors are being deployed across a range of industries, such as construction, infrastrucutre, mining, public safety, urban planning, archaeology, forestry, and agriculture.
How Does LiDAR Work?
LiDAR is similar to radar and sonar, but it uses light waves from a laser fired from a sensor or scanner, instead of radio or sound waves.
A LiDAR system calculates how long it takes for the light to hit an object or surface and then reflect back to the scanner.
The distance is then calculated using the velocity of light (299,792,458 metres per second). These are known as Time of Flight measurements.
This gives an accurate positioning point of where the laser hit. Depending on the sensor used, LiDAR units can blast hundreds of thousands of pulses per second, helping to build up a detailed visualisation of what the sensor is focusing on.
Each of these measurements, or returns, can then be processed into a 3D visualisation known as a point cloud.
Precise Data - Quickly
Here are some of the advantages of using LiDAR.
- LiDAR is an active system that uses ultraviolet, near-infrared light to image objects requiring no external light for effective mapping. This means it can be used in the dark.
- LiDAR surveying is extremely precise. It is particularly useful for mapping small features, such as high-voltage power lines.
- Not only is LiDAR data accurate, it can also collect dense geo-referenced point cloud data.
- When integrated with a drone, LiDAR sensing is a fast and efficient aerial surveying solution - covering large areas quickly and improving safety.
- LiDAR point clouds can be used to create 3D Digital Elevation Models of terrains, 3D Digital Surface Models, and 3D Models of buildings or industrial objects - benefiting a range of industrial and commercial applications.
- LiDAR has the ability to penetrate through multiple layers, such as a tree canopy, to see all the way to the ground. In traditional photogrammetry, vegetation can stop you from acquiring an accurate representation of what the ground topography looks like.
what can lidar be used for?
Range of industries benefiting from LiDAR.
Create A Digital Twin For Actionable Insights
LiDAR is a particularly popular tool for capturing the built environment, (such as buildings, road networks and railways).
It can also create digital terrain (DTM) and elevation models (DEMs) of specific landscapes.
- Digital Elevation Models (DEM): B are earth (topographic) models of the Earth’s surface. DEM allows you to generate slop (rise and fall in degrees or percent), aspect (slope direction), and hillshade (grayscale 3D representation of the surface, with the sun's relative position taken into account for shading the image).
- Digital Terrain Models (DTM): A 3D representation of a terrain surface. DTMs include contours, as well as features such as rivers, ridge lines, etc.
- Digital Surface Models (DSM): Incorporates elevations from natural and built surfaces, such as buildings, tree canopy, and powerlines. Essentially, a DSM represents the earth's surface and all objects on it.
LiDAR By Industry
How LiDAR is used across different industries.
LiDAR can benefit a range of missions, but it is typically used for surveying, as it can capture quick and accurate data which can be converted into detailed 3D models.
LiDAR can be used to benefit construction and infrastructure projects, creating 3D models and producing digital twins ideal for BIM applications.
These digital models can be used throughout the lifecycle of a project, allowing teams to scan for quality assurance, cross-check models and spot errors before they become a problem, conduct stockpile volumes, and monitor the progress of a development.
All of this information can then be shared quickly and easily with stakeholders and team members to improve communication.
This helps to drive efficiency, reduce costs, improve safety, and allow architectural design to be pushed to its limit.
Public Safety/Disaster Response
LiDAR has fast become a useful tool for public safety crews.
It is particularly useful for producing collision mapping and providing 3D forensic data - especially when an incident occurs at night.
Using LiDAR enables quick evidence collection; particularly useful after an RTC to help with a quick clear-up - freeing up commuters, and saving money on accident personnel. Evidence gathered can also be used in court.
LiDAR can also be used for disaster response/risk assessment. Visualisation of a LiDAR point cloud allows emergency responders to easily identify areas most affected by a disaster and understand terrain mobility. In some cases, this 3D view of a situation can provide unique information.
Agriculture and Forestry
LiDAR has a lot of use cases for environmental applications, including agriculture and forestry.
LiDAR can measure canopy heights, tree density, and location/heights of individual trees.
One of the key advantages of LiDAR is that it can be used in densely vegetated areas. While it can not penetrate vegetation, it can peer through the gaps in the leaves and collect multiple hits/returns.
LiDAR can also be used to highlight changes, such as surface degradation and vegetation growth.
In agriculture, LiDAR can be used to map out slope variations and provide increased yields through detailed monitoring.
LiDAR provides many benefits for mining, yielding precise inventory information, and accurate pit models and contour maps.
The advantage of LiDAR is that it can reveal the diverse variations in elevation, and provide geospatial information of the natural surface, mine infrastructure, and production volumes.
Covering areas quickly, a drone with LiDAR improves the efficiency of mining operations, and, as it can reach dangerous areas, it vastly improves safety.
For these reasons, LiDAR can be utilised for an entire lifecycle of a mining venture, from evaluating a pre-mine site, through to operating a mine, and the post-mine process.
LiDAR has revolutionised archaeology, making it possible to measure and map objects and structures that might otherwise remain hidden.
Another project saw researchers deploy LiDAR to spot more than 20,000 archaeological features in Mexico, which had been home to an ancient city.
LiDAR can also be used by archaeologists and conservationists to map structures that have already been found, such as Notre Dame Cathedral.
Thanks to its accuracy, LiDAR is an effective method for urban planners, helping to create 3D city models to help examine and identify issues in current urban areas and build cities for the future.
LiDAR point clouds can be used for mapping entire cities, helping to pinpoint structures or areas of interest in precise detail, while features such as road networks, bridges, and street furniture can be classified and extracted.
3D models can be useful for a range of purposes, such as mapping buildings and their heights, simulating new buildings, updating map data, emergency response planning, monitoring traffic, flood modelling, and detecting urban environment changes.
LiDAR mapping uses a laser scanning system with an integrated Inertial Measurement Unit (IMU) and GNSS receiver. This allows each measurement, or point in the resulting point cloud, to be georeferenced. Each ‘point’ combines to create a 3D representation of the target object or area.
LiDAR maps can be used to give positional accuracy – both absolute and relative, to allow viewers of the data to know where in the world the data was collected and how each point relates to objects terms of distance.
A Guide To LiDAR Sensors
Capture precise data with LiDAR.
Traditionally, LiDAR technology was large and expensive. For all of its benefits, the steep price tag and bulky modules made entry into the LiDAR market difficult. But this is changing.
More compact and affordable solutions are now available, empowering more professionals to take advantage of the technology.
And when paired with a drone, a LiDAR sensor can help surveyors and other users capture data extremely efficiently and safely.
Below are some of the options available.
DJI L1 Drone LiDAR Sensor
The DJI L1 integrates a LiDAR module and 20MP RGB camera, along with a high-accuracy IMU.
Engineered exclusively for the DJI M300 RTK drone, the L1 is a robust and efficient LiDAR solution, able to cover up to 2km² in a single flight and capable of achieving accuracies of 5cm (vertical) and 10cm (horizontal) at 50m flight altitude.
With a point rate of 240,000 points per second, which can be increased thanks to the L1's ability to support up to 3 returns, the L1 can be used to create highly detailed and dense point clouds.
Use Point Cloud LiveView to obtain real-time point clouds, while the RGB camera helps to give colour to your data. The RGB camera can also be used for photogrammetry missions.
The L1 is a rugged LiDAR solution, thanks to its IP44 rating, ensuring a reliable performance in difficult weather conditions and enabling more opportunities to capture data.
The L1 can be used in conjunction with drone survey software package, DJI Terra, for an end-to-end surveying solution within the DJI ecosystem.
GeoSLAM Zeb Drone LiDAR Sensor
HELIGUY.com™ has partnered with geospatial technology expert GeoSLAM to provide drone LiDAR solutions, adding the ZEB Horizon 3D scanner to our product portfolio.
The ZEB Horizon can be integrated with a DJI M600 via a UAV mount and can collect highly-detailed LiDAR point clouds.
This lightweight and compact aerial mapping technology has a range of 100m and can capture 300,000 points per second with an accuracy of 1-3cm.
It can be used in remote areas with poor GPS and enables operators to capture data for 3D modelling, conduct material volume and tonnage calculations, and collect floorplan and building measurements.
The ZEB Horizon can be utilised for a range of missions, including forestry, power lines, railways, farming, mining, and construction sites.
Data collected from ZEB Horizon can be processed using GeoSlam Hub and Draw, turning your 3D data into actionable information and valuable deliverables in minutes.
Livox LiDAR Solutions
Livox Technology Company Limited is an independent company founded in 2016 through DJI’s Open Innovation Program.
Committed to helping customers incorporate LiDAR sensors into efficient commercialisation of their projects, Livox has released a number of LiDAR sensors, including the industrial-grade Mid series.
The Livox Mid is a compact and high-performance LiDAR sensor, with a 260-metre detection range. It can achieve 2cm precision, and a vertical and horizontal accuracy right down to 0.1°. It is suitable for a range of applications, including mapping and robotics.
At AirWorks 2020, Livox announced the imminent release of the Livox Avia, which will be compatible with the DJI M300 RTK and M200 Series of drones.
This compact solution, designed for easy integration, will be sub 500 grams, have a wide 70-degree FOV, and a detection range of up to 500 metres. It will be able to create high-density point clouds and support up to three returns.
best lidar drones
Harness the DJI drone ecosystem.
What Options Are Available For A LiDAR Drone Survey?
DJI is the world's leading drone manufacturer, and there are a number of UAS in its ecosystem which can be deployed for drone LiDAR missions.
The most suitable DJI drones for LiDAR are the M300 RTK, M210 Series V2 (including the M210 RTK), and the M600 Pro.
These industrial-grade drones can utilise Payload SDK to carry third-party LiDAR scanners.
LiDAR v Photogrammetry
Pick The Solution For Your Needs
In drone survey missions, the choice between photogrammetry (right image) and LiDAR (bottom image) depends heavily on your mission and your budget.
Drone photogrammetry is when a drone captures a large number of high-resolution images over a specific area. You can use these images to reconstruct the terrain in 3D using image overlap and sufficient ground control.
Photogrammetry is best for mapping, surveys, mining, broad-coverage combined with high horizontal and vertical accuracy.
In contrast, LiDAR (which stands for light detection and ranging) is a remote sensing technology that uses rapid laser pulses to map out the surface of the earth.
LiDAR is useful when used to create high-resolution digital surfaces, terrain and elevation models used for various business applications.
Both photogrammetry and LIDAR can provide remarkable levels of 3D model accuracy, especially compared with terrestrial sampling methods.
A big advantage of photogrammetry is that this technique not only generates accurate 3D models, but also full-colour, high-resolution information for every point on that model, giving clear visual context.
This makes interpretation and analysis of the results much easier compared to a pure LiDAR point cloud.
However, when it comes to surveying land with dense vegetation, where the light pulses can still penetrate between branches and leaves, LiDAR gets highly-detailed information.
This is a big advantage over photogrammetry, as photogrammetry can only produce accurate surveys when there is sparse vegetation on site. While LiDAR does have similar limitations, under good conditions it can penetrate areas with up to 90% vegetation. (Photogrammetry sits closer to the 60% mark).
LiDAR is also a better option for mapping narrow structures, such as power lines and railway tracks, and it can capture data in poor lighting conditions.
LiDAR gives you a point cloud, but because photogrammetry is stitching photos together to create your model, you get the visual details of every feature on your site. It means that photogrammetry is better suited for surveys which require visual data.
One of the biggest differences between photogrammetry and LiDAR is the price.
Thanks to innovation, LiDAR has become a much more accessible solution than it used to be. That said, it still comes at a price, and can be a more costly solution than photogrammetry.
In truth, both LiDAR and photogrammetry and powerful tools for aerial surveying and mapping. Both have their strengths and weaknesses. More often than not, it depends on which is best suited for the specific job in-hand.