LiDAR and RADAR remote sensing are some of the most common remote sensing techniques in use today. LiDAR uses light rays or lasers to send and receive signals while RADAR uses radio signals to send and receive signals to and from an object. But what are the differences between these two remote sensing techniques?
LiDAR Remote Sensing:
1. Uses laser beams:
LiDAR technology uses light pulses or laser beams to determine the distance between the sensor and the object. The laser travels to the object and is reflected back to the source and the time taken for the laser to be reflected back is then used to calculate the distance.
2. Measures precise distance measurements:
Because of the nature of the laser pulses, LiDAR is mostly used to measure the exact distances of an object. The laser pulses travel at the speed of light which increases the accuracy of the measurements.
3. Measures atmospheric densities and atmospheric currents:
LiDAR technology can be used to measure atmospheric densities of various components such as aerosols and other atmospheric gases. This is because the pulses are more accurate and have a shorter wavelength that can be used to acquire accurate data.
4. Used in obtaining 3D images with high resolution:
LiDAR technology is capable of creating high resolution images of an object at any surface and this is why it is popularly used in mapping and other topographical uses. Based on the speed of the laser pulses from LiDAR sensors, the data is returned fast and with accurate results.
5. It is adversely affected by smoke, rain and fog:
Unlike RADAR technology, LiDAR pulses are adversely affected by atmospheric weather conditions such as dense fogs, smoke and even rain. The light pulses will be distorted during flight and this will affect the accuracy of the data collected.
6. It has a higher measurement accuracy:
Unlike RADAR, LiDAR data has a higher accuracy of measurement because of its speed and short wavelength. Also, LiDAR targets specific objects which contribute to the accuracy of the data relayed.
7. LiDAR is cheaper when used in different applications:
LiDAR technology is cheaper when used in large scale applications. This is because it is fast and saves a lot of time and it is also not very labor-intensive unlike other methods of data collection.
8. Data can be collected quickly:
Because of its speed and accuracy of the laser pulses from LiDAR sensors, the data can be collected fast and with utmost accuracy. This is why LiDAR sensors are used in high capacity and data intensive applications.
9. It does not have geometric distortions:
LiDAR sensors are highly accurate and are therefore not affected by geometric distortions. The data collected will be precise and accurate and will map the exact location of the object in the image.
10. It can be integrated with other data sources:
LiDAR data can easily be integrated with other data sources such as GPS and used in mapping and calculation of distances. This can also be applied in forest mapping and other remote sensing technologies.
11. It allows for data collection at night and during the day:
LiDAR technology, unlike other remote sensing technologies, allows for data collection both during the day and during the night. This is because the laser pulses are not affected by light rays.
12. LiDAR can collect accurate elevation data in dense forests:
Unlike RADAR, LiDAR sensors are capable of obtaining accurate elevation data from dense forests with distorted canopies because of their high penetration abilities.
13. It allows for detection of small objects due to the shorter wavelength:
LiDAR sensors can detect even the smallest of objects from the surfaces because of the short wavelength. The data returned will be independent of each object on the surface.
14. LiDAR can build an exact replica of 3D image of the object:
LiDAR technology is used to recreate an exact replica of the object being detected and measured in 3D images. This is because of their high accuracy.
15. It has an operating altitude of between 500m – 2000m
Lidar has an operating altitude of about 500m-2000m because of its short wavelength. This means it will not be effective beyond these altitudes.
16. Determines distance to objects:
LiDAR technology is mostly used to determine the distance to the objects only and no other geometrical characteristics of the object.
17. It can cover large areas quickly:
Laser pulses are fast and accurate and can return data within a very short time. For this reason, they are capable of covering large areas within the shortest time.
18. LiDAR gives very large datasets:
LiDAR sensors are capable of giving very large datasets because of their ability to cover large areas within a short period of time.
19. Not guided by any international protocols:
There are no international protocols that govern the use and operation of LiDAR sensors and data and how to manipulate that data.
LiDAR has a variety of applications including transport, forestry, agriculture, military, and security but its most common applications can be found in agriculture and transport.
RADAR Remote Sensing:
1. Uses Electromagnetic waves:
RADAR technology uses electromagnetic waves or radio signals to determine the distance and angle of inclination of objects on the surface.
2. It can operate in cloudy weather conditions and during the night:
Unlike LiDAR, RADAR technology is not affected by adverse weather conditions such as clouds, rainfall or fogs.
3. It has a longer operating distance:
RADAR technology has a longer operating distance although it takes a longer time to return data regarding the distance of the object.
4. Cannot detect smaller objects
It does not allow the detection of smaller objects due to longer wavelength. This means that data regarding very tiny objects on the surface may be distorted or insufficient.
5. No 3D replica of the object
It cannot provide an exact 3D image of the object due to the longer wavelength. This means that the image will be a representation of the object but not an exact replica of the object characteristics.
6. Determines distance from objects and their angular positions
Apart from the distance from object, RADAR technology can also provide the angular positions of objects from the surface, a characteristic that cannot be measured by LiDAR.
7. RADAR measures estimated distance measurements:
RADAR technology does not give the exact accurate measurements of distance and other characteristics of the object because of the distortions.
8. Radar beam can incorporate many targets:
A RADAR beam can have several targets at the same time and return data on several objects at the same time. However, this may exclude smaller objects within the target field.
9. Radar may not distinguish multiple targets that are close together
RADAR technology cannot distinguish multiple targets within a surface that are closely entangled together. The data may therefore not be accurate.
10. RADAR takes more time to lock on an object:
RADAR, unlike LiDAR pulses, travels at a lower speed which means more time is needed to lock onto an object and return data regarding the object.
11. Radar has a wide beam that targets multiple objects:
RADAR beams are wide and have the capability of targeting multiple objects at the same time. The downside of this is that the data collected may not be as accurate as it should be.
12. Radar is largely affected by external interference:
RADAR beams are affected by other external interference such as the forest canopies and dense forest which may limit the quantity and quality of data returned.
13. Data collection takes a bit more time:
The collection of data using radar signals take more time than when using LiDAR because radar signals take longer to reach the surface.
14. Requires an antenna for transmission:
Radar signals require the radar transmitter to have an antenna for sending and receiving signals from the object.
15. RADAR is less accurate than LiDAR:
RADAR data is less accurate than LiDAR data because of the incomplete data returned from radar systems regarding objects. For instance, small objects may not be captured by radar.
16. RADAR is distorted by noise
RADAR data may also be distorted based on the noises encountered during the signal transmission. As a result, the data collected may be incomplete or inaccurate.
17. RADAR is used to find range, velocity and position of the object
The data returned by RADAR signals include the range, of the object, position and even the velocity of the object as opposed to LiDAR which calculates the distance and position of the object.
18. Cannot penetrate dense forests
Unlike LiDAR, radar signals cannot collect accurate elevation data from dense forests due to their incapacity to penetrate the dense canopies.
19. Radar images are of lower resolution than LiDAR images:
Because of the low speed of transmission and reduced accuracy of the data recorded by radar signals, the resolution of images returned by radar may be of lower quality as compared to that returned by LiDAR.
RADAR has a variety of applications including military, security and transport but its main usage is in aviation industry and military weaponry.
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