Context: The coronavirus pandemic has stopped archaeologists from going to dig at sites, but that did not stop a U.K.-based team from continuing their research.
More on News:
- Equipped with airborne survey data, a team of volunteers, locked down in their homes, sat and analysed thousands of images derived from Light Detection and Ranging (LiDAR) data.
- In this method laser light was used to survey a site and its reflection is measured with a sensor.
- The method is commonly used by geologists and surveyors to make high-resolution maps.
LiDAR in India:
- As per experts the technology had immense potential for India.
- Though LiDAR has been used for agriculture and geology-related applications, our country has still not used it in archaeology.
- The problem is that the data needs to be bought and processed by experts which sometimes is very expensive.
- LiDAR will also help in understanding domestic architecture, and defensive architecture like moats and fortifications in the area.
- Using this we can even look at the hydrology and water management systems in greater detail, all of which is probably under dense vegetation.
- LiDAR stands for light detection and ranging.
- It was first used on a spacecraft during the Apollo 15 mission in 1971, when astronauts mapped the surface of the moon.
- It is basically a remote sensing method that uses light in the form of a pulsed laser to measure distances to the subject.
- A LiDAR sensor fires off beams of laser light and then measures how long it takes for the light to return to the sensor.
- The basic mechanism is known as “time of flight” measurement in which a laser beam is emitted towards an object, reflected off of the object and then collected in a sensor located within the LiDAR module.
- These light pulses – when combined with other data, generate accurate, high-resolution three-dimensional information of the object.
Application of LIDAR technology:
- LiDAR is used to collect high-density data in order to produce high-resolution maps.
- Ground based surveys and aerial surveys: LiDAR sensors are being fitted under drones to create readings of the terrain, transmission lines, buildings, and trees.
- LiDAR is currently being used to provide 3D maps of the ground beneath.
Disadvantage of LiDAR:
- It can’t perform well in fog, rain, snow and dusty weather.
- Need secondary cameras: LiDAR also struggles to detect a glass wall or door, which is why smartphone manufacturers and self-driving cars makers use LiDAR along with secondary cameras and sensors.
SONAR, RADAR and LIDAR:
- Sonar and Radar too can reveal information about an object’s shape, size, direction and height.
- SONAR : Sonar (short for sound navigation and ranging) relies on sound waves to detect objects and hence is usually used to detect objects underwater.
- Radio waves: Radar (short for radio detection and ranging) uses radio waves to determine an object’s distance or range.
- Radio waves can work over a long distance and perform better in dusty conditions, in this sense it is better than SONAR.
- Lidar is better as:
- Radar can plot the location of a vehicle from miles away, the location can only be known as a featureless “blip”.
- The laser precision of LiDAR can visually map individual features of a vehicle or an environment in what is known as a “point cloud,”.
- The LiDAR sensor provides continuous 360 degrees of visibility and accurate in depth information.
Image Source: The Hindu