Last updated on November 24th, 2023 at 08:42 am
Remote sensing technologies have uplifted and revolutionized human life and plays an important role in shaping the world around us. There are several technologies used in remote sensing and the most important remote sensing technologies are LiDAR, Radar and Sonar.
In this blog, let’s look at what these three technologies are, how they work and compare these three technologies of remote sensing.
Difference Between LiDAR, Radar And Sonar
| Technology | LiDAR | Radar | Sonar | |
|---|---|---|---|---|
| Definition | Light Detection and Ranging | Radio Detection and Ranging | Sound Navigation and Ranging | |
| Operating Principle | Laser pulses and reflection of light | Radio waves and measurement of reflections | Sound waves and underwater sensing | |
| Applications | – Autonomous vehicles and navigation – Environmental mapping and monitoring – 3D modeling and urban planning – Forestry and agriculture – Archaeology and cultural heritage preservation | – Aviation and air traffic control – Weather forecasting and meteorology – Military and defense applications – Maritime navigation and surveillance – Collision avoidance systems | – Underwater exploration and mapping – Fishery and marine resource management – Submarine navigation and detection – Hydrographic surveying – Offshore oil and gas exploration | |
| Advantages | – High accuracy and precision – Detailed 3D point cloud data – Ability to penetrate vegetation cover | – Ability to operate in various weather conditions – Long-range detection capabilities – Cost-effectiveness for certain applications | – Effective underwater detection and imaging – Wide coverage area – Cost-effectiveness for marine applications | |
| Limitations | – High cost of equipment and data processing – Limited performance in adverse weather conditions – Sensitivity to reflective surfaces | – Lower resolution compared to LiDAR – Difficulty in distinguishing small objects – Vulnerability to interference and clutter | – Lower resolution compared to LiDAR – Limited performance in turbid or shallow waters – Potential impact on marine life |
LiDAR – Light Detection And Ranging
LIDAR stands for Light Detection and Ranging. It is used in generating 2d and 3d maps of the environment primarily by using two measurement techniques, TOF ( Time Of Flight } and Laser Triangulation. Though lidar can be used for many applications, its primary use case is in autonomous vehicles for generating a 2d or 3d map of their environment and using the generated map to Localise ( Finding where the vehicle is by comparing with the generated map ) and navigate to the destined location.
How LiDAR works:
A Light source such as Laser is mounted on top of a rotating plate and the light source sends out a beam of light at a particular frequency and waits for the light to reflect off of a surface. By calculating the time taken for the light to be received, the distance between the source and the object is determined. Since the Light source is placed on top of a rotating platform, the platform can be rotated to every angle and the object at 360° is captured and a 2D map is generated. When multiple light sources are stacked on top of each other and the same process is repeated, we get a 3D mapping of the environment.
Applications of LiDAR
- Robotics: The main place where lidar is used is in the Autonomous vehicles and Autonomous robots. The use of lidar here is for localisation and navigation purposes.
- Aerial Inspection: The lidar is mounted on top of a Drone or a UAV and it is used for industrial inspections, powerline inspections, industrial asset monitoring and so on.
- Agriculture: Lidar along with other sensors is used in Agriculture for identifying location to irrigate instead of irrigating the entire area thus saving water and other resources.
- Lidar in Space: Lidar is used in robots that are mapping the other planets and natural satellites like the moon. But one other peculiar use case that I first hand saw for the use of lidar in space is for docking in space.
Radar – Radio Detection And Ranging
Radar is a short form of radio detection and ranging. Besides, it’s a communication that uses waves to identify and pinpoint objects. Initially, it was used by ship captains to communicate with their agencies’ radio towers. With time, they noticed that objects in towers and the craft caused interruptions hence preventing effective communication. Therefore, what began as an inconvenience progressed to new defense strategies for water and the land and the sky.
How Radar Works
The radar operates by sending out radio waves and waiting for the reply back, just like an echo. The time it takes for the wave to return shows how far away the object is. Besides, sending signals out from distinct points helps determine the position of the object. Usually, the radar system has an antenna, a radio transmitter, and objects for waves to reflect on. The antenna passes the information to the receiver, which intensifies the echo that bounces off the objects and signals displays them to the user in a better typical visual way.
Applications of Radar:
- Aviation and Air Traffic Control: Radars are used in finding the position, altitude and speed of the airplanes in air ports to monitor traffic to ensure safe and efficient flight operations.
- Weather Forecasting and Meteorology: Radar systems are used in detecting clouds, rain and strom data and analyzing it to make accurate weather predictions. This can be used to detect severe weather conditions and act accordingly.
- Military and Defense Applications: Radars are used in the military for detection, tracking and target detections. It is mainly used in air defense, drone and missile detection in the military.
- Maritime Navigation and Surveillance: In marine, the radar is used in assisting ships on identifying other ships and objects in the sea to safely navigate in the ocean.
- Aerospace and Space Exploration: Radar is used in the aerospace and space industry to find the altitude of objects and topography of the planetary surfaces. Synthetic Aperture Radar (SAR) is mounted to satellites and aircraft to create high-resolution images of the Earth’s surface for mapping and monitoring environmental changes.
Sonar – Sound Navigation And Ranging
Sonar Stands for Sound Navigation And Ranging. It is a technique used mostly to explore and map the ocean bed and detect objects under the ocean. There are two types of sonar and each has its own advantages and disadvantages.
The sonar is widely used in ships and submarines to map the ocean bed or to detect objects underwater. The reason why sonar is widely used under water is that radar which uses electromagnetic waves tends to be absorbed and weakened beyond useful range in water medium. Whereas in contrast sound waves tend to travel effectively in water and die off quickly in air.
How Sonar Works
Sonar usually has a transmitter and a receiver. It uses a technique of transmitting sound waves usually in varying frequencies from infrasonic ( very low frequency sound waves ) to ultrasonic ( very low frequency sound waves ) and receiving the wave bouncing off of an object and the time difference is used to calculate the distance between the object.
Applications of Sonar:
- Submarine and ship navigation
- Submarine detection and tracking
- Fisheries and marine research
- Anti-submarine warfare
- Underwater mapping and surveying
- Environmental monitoring
Conclusion
LiDAR, Radar and Sonars are the most important tools in remote sensing and they enable us to gather important data to monitor our environment and make informed decisions in a wide variety of fields. Each technology has their own potential and boundaries. Understanding them helps us in determining the correct tool that fits for the job.
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