LiDAR, Radar and Sonar are the modern remote sensing techniques used by various professionals to collect and analyze data. They use different mediums to transmit various types of signals to and from the objects and then analyze the time taken to measure the distance between the transmitter and the objects. Below are some of the differences between the three remote sensing technologies.
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.
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.
SONAR Remote Sensing
1. Uses sound waves:
Sonar stands for Sound Navigation and ranging. It transmits sound waves that are then returned in form of echoes which are used to analyze various qualities or attributes of the target or object.
2. Used to detect under water objects:
Sonar is mainly used to detect under water objects because the sound waves can penetrate the water depths to the bottom of the sea.
3. It is affected by variations in sound speed:
Sound travels slowly in fresh water than in sea water. This means that the variations in the speed of sound may affect the return echoes which may also have an impact on the data or attribute of the target.
4. Mostly used to find actual sea depth:
Because of its unique capabilities of penetrating sea water, sonar is mainly used to calculate the depth of the sea because it is fast and accurate.
5. Is not affected by surface factors:
The sound waves are not affected by the calmness or the roughness of the water surface. They can penetrate even tides and still get the necessary data required.
6. It has adverse effects on marine life:
Sound waves from sonar have adverse effects on marine life such as whales that also depend on sound waves.
7. Sonar generates a lot of noise:
The sound waves from the transmitters usually generate a lot of noise that also have an effect on the marine life that live deep sea.
8. Passive sonar does not require a transmitter and a receiver:
Unlike active sonar that transmits with the help of a transmitter and also relies on a receiver, passive sonar does not transmit. It listens without transmitting
Active sonar may lead to scattering from small objects as well as the sea bottom and surface which may cause interference.
10. Causes decompression sickness:
SONAR may cause decompression sickness that may be fatal.
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