archaeologists-using-lidar-technology-amidst-lockdown

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 Technology:

  • 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.

Source: 

https://www.thehindu.com/sci-tech/science/how-archaeologists-continued-digging-from-home-during-lockdown/article31760027.ece

Image Source: The Hindu