Urban planning is a dynamic field, and technological upgrades are necessary to stay ahead of the curve. As the urban topography continues to expand, planning becomes correspondingly more complex. In this context, LiDAR tech is a game-changer, allowing planners to build smart cities that will adapt to and evolve with future challenges.
What is LiDAR Technology?
LiDAR is the short form of “Light Detection and Ranging.” It is a technique used for remote sensing. Now, what is remote sensing? It is about obtaining information on an object’s shape and position without the need for any physical contact.
Definition and Basic Principles
LiDAR is a remote-sensing method that works by precisely measuring movements and distances in an environment using laser beams. The measurements are taken in real-time. The basic working principle is simple. A small laser is first beamed at an object’s surface. Sensors measure the time required by the laser to return to the emitter. This helps calculate the distance of the surface from the sources.
So,
Distance = Speed of light x Time taken for laser to return to source
How LiDAR Works
The working mechanism of LiDAR is not very different from sonars and radars. You may already know that radars and sonars work by emitting energy waves to detect and track objects. LiDAR is no different. Microwaves are emitted in radar technology. Sonars are based on sound waves. Similarly, LiDAR works with reflected light.
Light helps with faster measurement of distance. This is because the speed of light is much higher than that of sound and microwaves. LiDAR is also more precise than sonar and radar. The results you would get from LiDARs will also be of higher resolution.
What is LiDAR Scanning?
LiDAR scanners are devices that can capture clouds of billions of points routinely. Now, what is a point cloud? It is a set of data points in a three-dimensional space.. You can also think of it as XYZ axes. Every single point indicates one spatial measurement on the surface of an object. The entire surface of an object is represented by point clouds.
Understanding LiDAR Scanning
LiDAR scanning works when laser light is emitted from mobile systems like drones or cars. The light can be beamed through air as well as water. It can also be pulsed through vegetation. The light is received back by the LiDAR scanner. This helps measure angles, depth, and distances. How many points and light reflections are measured depends on the scanning speed.
Benefits of LiDAR Scanning
As you already know, the use of light to scan objects makes LiDAR faster and more precise than sonars and radars. Hence, accurate scans of surfaces are one big advantage. The technology also makes 3D mapping more accurate.
You also don’t need an antenna to transmit and receive signals with LiDAR laser scans. Signals are transmitted and received using lasers and optics. With antennas out of the scene, devices become more compact.
The lower wavelength of LiDAR systems is another advantage over radars and sonars. How is low wavelength an advantage? Well, identification of extremely tiny objects or particles becomes possible with lower wavelengths. LiDAR will let you detect and track objects as minute as cloud particles. You cannot do this with sonars. Radars are not as efficient as LiDAR laser scans in measuring small particles and structures. Radars will not produce results as detailed and high-resolution as LiDARs.
Here is an overview of the differences:
| Radar | Sonar | LiDAR | |
|---|---|---|---|
| Wave nature | Radio waves | Sound waves | Light waves |
| Penetrates | Cloud and rain | Water and air | Air |
| Reflected by | Big solid objects | Solid objects | Opaque surfaces |
| Object detection | Large objects at a long distance | Underwater objects | Small structures and fine surface details |
| Main application | Measure the distance of static and moving objects | Mapping the underwater environment | Highly accurate surface mapping |
| Resolution | Moderate | Low on land, High in water | Very high |
| Detail recognition | Large objects only | Moderate details underwater | Fine details on the surface |
| Range | Very long, over 100 kilometers | Varying, depends on the sound wave frequency | Medium range, several kilometers |
| Line of sight | Needed for optimal performance | Not strictly needed | Strictly needed |
| Environment | Works well in all weather conditions | Affected by noise and turbulence in water | Affected by weather interference |
| Cost | Varying, affordable to expensive | Varying, inexpensive to very expensive | Very expensive |
Understanding 3D LiDAR Technology
Now that you know what LiDAR scanning is, let’s understand 3D LiDARs. “LiDAR” is typically a broader term. By “3D LiDAR,” we refer to a type of LiDAR that specifically records three-dimensional information.
How 3D LiDAR Differs from Traditional LiDAR
Traditional LiDAR can also be called 2D LiDAR. The traditional form of LiDAR can only run scans on a single plane. Therefore, it only captures data from the flat area of an object, be it vertical or horizontal. Both 2D and 3D LiDARs measure distance by capturing the time taken for laser light to reflect off surfaces. However, the 3D system repeated the process millions of times to generate a 3D point cloud.
2D LiDARs produce a single laser beam at a fixed angle or plane. But 3D LiDARs emit multiple laser beams at a variety of angles. This is why you can get a multi-dimensional scan of the environment with 3D LiDARs.
Let’s take a quick overview of the differences between 2D and 3D LiDARs.
| 2D LiDAR | 3D LiDAR | |
|---|---|---|
| Accuracy | Accurate obstacle detection | Accurate 3D mapping |
| Application | Obstacle detection and path planning | 3D modeling objects and textures |
| Beaming | Single laser beam | Multiple laser beams |
| Scanning | Single plane (X & Y) | Three-dimensional (X, Y & Z) |
| Localisation | Low (2D point cloud) | High (3D point cloud) |
| View | Bird’s eye | 360-degree |
| Range | ≈40 meters | ≈200 meters |
| Speed | Extremely fast | Very fast |
| Depth sensing | No | Yes |
| Works in darkness | Yes | Yes |
| Affected by weather elements | Yes | Yes |
| Cost | Less costly | More costly |
| Portability | Less bulky | More bulky |
Advantages of 3D LiDAR
Higher accuracy is the main advantage of 3D LiDARs. You will find the accurate 3D measurements essential in high-precision applications. 3D LiDARs also let you capture large volumes of point data at every moment. This can help you bring down project costs.
You will also find this useful when you need to get work done quickly and efficiently. Versatility is another major advantage of 3D LiDARs. You can scan a range of objects as well as textures with it. The collected point clouds will also help you with mapping and modelling later.
Let’s list the specific advantages of 3D LiDARs.
- Precise visualisation: You cannot always document complex structures fully with traditional methods of surveying. 3D LiDAR systems will help you get a precise and detailed model of the built environment.
- Improved surveying: The traditional method of surveying consumes a lot of time and resources. However, 3D LiDARs use laser scanning. So you need less time to record the conditions of the built environment. Recording the condition of hard-to-reach places also becomes efficient.
- Advanced designing: 3D modelling and planning become easy with 3D LiDARs. It becomes possible to get a complete digital model of structures. This will help you identify faults and conflicts related to design. Hence, the chances of costly design modification during the construction stage are minimised.
- Conflict resolution: 3D scanning makes it possible to spot disputes among different building systems. For example, you can identify collisions between electrical and plumbing systems with 3D scans. This helps reduce reworks and unnecessary spending.
- Conservation: You can document the structure of an old building with 3D scans. This can help digitally recreate important sites, thus contributing to heritage restoration.
- Remote collaboration: 3D point clouds captured by LiDARs can be remotely distributed. This makes the decision-making process easy. Project participants can remotely work on a construction project. They no longer have to be physically present at the site all the time.
- As-built assessment: 3D scans will help you digitally capture a building’s structure. This will help you make a comparison between the built and the planned design. Hence, LiDARs allow better quality control than traditional surveying.
- Risk minimisation: 3D scans eliminate the need to visit sites physically to take measurements. This will help you reduce the risks to workers. In traditional surveys, the need to run measurements on-site can expose the workers to hazards.
- Cost and time savings: 3D scanning will help you save time and cost. You will be able to prevent expensive reworks. This will help you avoid delays as well.
- Data-driven maintenance: LiDARs can also help you with easy maintenance of buildings. 3D scanning can help you understand the conditions of structures. The scans can also be used for monitoring changes. Therefore, you will be able to detect the maintenance needs and come up with preventive measures.
LiDAR Laser Scans: Enhancing Accuracy in Surveying
LiDAR is being widely used for 3D property scanning and construction surveying. Surveying is about measuring and mapping the land or topography of a construction site.
How do LiDAR Laser Scans Work?
LiDAR-based surveying can be done in aerial or terrestrial modes. Aerial LiDAR surveying requires mounting scanners on a plane or a helicopter. Drone LiDAR scanning can also be done.
Terrestrial LiDAR surveying involves mounting scanners on a stationary or mobile setup. You can mount the scanner on a tripod or on your car as well.
Comparison with Traditional Surveying Methods
If you want to do surveying, LiDAR scanning is better than traditional approaches. LiDAR laser scans can help you create 3D models and maps of your construction site. You can also work with it in all lighting conditions. LiDAR scanning is also equally effective in measuring different objects. It means you can survey buildings and structures as well as landscapes. This is why it is being widely used in 3D property scanning.
High precision of LiDAR returns more accurate results. The process of data collection is also fast and efficient with LiDAR. You also enjoy versatility as scanning is possible for all environments and in every condition. This makes it ideal for scanning for hazardous structures in terrains with difficult geometry. LiDARs can also penetrate dense objects. This helps get structural and surface information that photos cannot reveal.
You will also be happy to know that LiDAR-based surveying is more cost-effective than the traditional form. Let’s take an overview of the similarities and differences between traditional surveying and LiDAR scanning.
| Parameters | Similarities | Differences | |
|---|---|---|---|
| LiDAR | Traditional Surveying | ||
| Mapping and modelling | Both are used for mapping and modelling physical environments. | Mapping and modeling are done using laser-based scanners. | A central point is set first. The distance and elevation of various points from it is measured manually using tools. |
| Accuracy | Both methods are high in accuracy. | Highly precise, as millions of data points are collected through laser scanning. | Not as precise as LiDAR. Environmental factors and human error can affect accuracy. |
| Time and labour | Both methods help you get measurements quickly and easily. | Extremely fast and convenient. The speed of light is used by computers to calculate distance. | A team of surveyors must spend time and energy setting up tools. Measuring and data entry is also done manually. |
| Data output | Data from both approaches can be used to recreate digital versions of the environment and structures. | LiDAR data is incredibly precise. The smallest structures and finest textures are accurately captured. | The level of detail that can be captured depends on the quality of tools and the skills of operators. You also need to put more effort into capturing the finer details. |
| Versatility | Both methods require you to have objects within the line of sight. | LiDAR scanning can be done from air and ground vehicles. | You need to be present on the site to perform traditional surveying. |
Applications in Mapping, Construction, and Urban Planning
Now that you know the types and advantages of LiDAR technology, let’s check out its use in industries.
Mapping with 3D LiDAR
LiDAR is widely used in building Digital Elevation Models (DEMs). These models represent the bare surface of the Earth in 3D. Natural features are not included in the maps.
LiDAR is also used in building Digital Terrain Models (DTMs). These models augment DEMs with natural features. It means that vegetation and rivers are also mapped in DTMs.
LiDAR is also used in generating Computer-Aided Design (CAD). These are 2D maps based on line and point drawings for showing features and details on a site.
LiDAR also helps generate 3D building models. These geo-located models reveal the layout and dimensions of structures on construction sites. The models also reveal the dimensions of the structures. 3D property scanning processes have become more efficient with LiDAR.
Construction Industry and 3D LiDAR
LiDAR technology is being used in the construction industry to create 3D models of roads, bridges, buildings, and tunnels. The technology is not only making construction planning efficient, but safer as well. The data captured by LiDAR also assists with site documentation and analysis.
Urban Planning with LiDAR
The combination of Artificial Intelligence (AI) and 3D LiDAR technology is revolutionising smart city development and urban planning. If you integrate these two technologies, you will be able to create detailed 3D models of an entire city. Such 3D city models are improving sustainable planning tasks. You can assess how dense a population is. You can also understand and optimize the flow of traffic. The technologies together also help in anticipating infrastructure needs.
Challenges and Future of 3D LiDAR Technology
Every technology has its limitations. Let’s look at the challenges and limitations of 3D LiDAR technology.
Current Limitations and Challenges
The challenges and limitations of LiDAR technology are mostly due to the use of light waves. Let’s understand why these limitations exist.
- Cost and Expertise: One of the challenges with the remote-sensing technology is related to its implementation costs. LiDARs are economical if deployed on a large scale. If you want to collect data on small areas, you will need to make large investments in equipment. You also need people with advanced skills and technology understanding. Otherwise, you will fail to spot inaccurate or inconsistent data.
- Limited Contextual Details: One limitation is that LiDARs return non-colorized data. You might find it difficult to interpret the data if you lack overlaying RGB pictures. You will also notice the sparseness in point clouds. It is less sparse in traditional methods like photogrammetry. Hence, LiDAR will give you a rough sense of an object’s shape but will miss out on contextual details.
- Dense Obstacles: LiDARs are also not very effective in sites with extremely dense vegetation. The laser light beams would fail to touch ground covered by a thick canopy.
- Weather Interferences: Elements of weather, like fog and rain, can also cause interference to LiDARs. Accuracy of scanning is also dependent on the surface of a structure and the sensor’s calibration. The inferences can lead to errors in LiDAR output. The captured data may also be inconsistent if interferences are not fixed.
- Data Format: A cloud point format is generally used for saving LiDAR output data. You will find it challenging to perform visualisation and analysis. Specialised software is needed to read the data. Your workers must also be trained on the use of specialised software.
- Line of Sight: You need to ensure that LiDAR scanners are in a clear line of sight with the structure to be measured. The laser will also face issues with reflective surfaces. Moreover, LiDARs can detect moving objects but are not good at modeling them.
Future Advancements
The future promises to make LiDAR technology even more advanced. Let’s have a look at what the future holds.
- More Compact and Hardy: LiDAR systems were based on mechanical parts in the early days. The systems were bulky. Mechanical parts also made them prone to wear damage. The size and shape of the early systems also made integration difficult. However, solid-state LiDARs soon gained popularity. Optoelectronic devices replaced moving components. Phase control methods made readings more accurate.
- More Accurate and Fast: The future is promising developments in chip-scale LiDAR. You will soon notice LiDAR sensors on photonic integrated circuits. The developments are being made to meet the evolving requirements of the automotive industry.
- Better Registration: Individual laser scans are compiled into a combined point cloud. Point clouds are made from laser scans to further create 3D models. This process is known as registration. Today, targets have to be placed in a zone for registration to happen. Views are manually lined up on a computer. LiDARs of the future are being built for performing real time pre-registration scans.
- Increased Capacity: Future LiDAR systems will have greater data collection capacity. Hundreds and thousands of points are already being collected by the scanners today. However, there have been advancements in this area. You can already find laser scanners capable of collecting more than 2 million points every second.
Conclusion
LiDAR is a reliable technology to collect accurate and detailed terrain data or maps. It simplified tasks like 3D property scanning and terrain mapping. It is also very precise in motion tracking and tiny object detection. LiDAR technology offers precision and versatility that sonars and radars cannot match. LiDAR equipment can be expensive. But it is economical in large-scale applications. Consider replacing your traditional site surveying and 3D mapping systems with LiDAR for maximum accuracy and efficiency.