A. LiDAR, which stands for Light Detection and Ranging, is a remote sensing technology that uses laser light to measure distances to the Earth''s surface. A LiDAR system, which is often mounted on an aircraft or a drone, fires rapid pulses of laser light at the ground. A sensor then measures the time it takes for each pulse to bounce back. By combining this data with precise GPS and inertial measurement unit (IMU) data, the system can generate an extremely detailed and accurate three-dimensional map of the landscape.
B. One of LiDAR''s key advantages is its ability to "see" through vegetation. While some laser pulses are reflected by the forest canopy, others penetrate through gaps in the leaves and branches to reach the forest floor. By analysing the different return signals, scientists can digitally remove the vegetation, revealing the true shape of the ground surface underneath. This capability has made LiDAR an invaluable tool in a wide range of fields.
C. In archaeology, LiDAR has been revolutionary, leading to the discovery of ancient cities, roads, and agricultural systems that have been hidden for centuries beneath dense jungle canopies, such as those of the Maya in Central America. In forestry, it is used to measure forest height, density, and biomass with incredible precision, which is crucial for managing timber resources and monitoring deforestation. It is also used in geology to map fault lines, in urban planning to create detailed city models, and in the development of autonomous vehicles to help them perceive their surroundings.
D. As LiDAR technology becomes more accessible and affordable, its applications continue to expand. It is a powerful tool for monitoring environmental change, from coastal erosion to the melting of glaciers. By providing highly accurate, high-resolution topographical data, LiDAR is transforming our ability to map, understand, and manage the world around us.
IELTS Practice Tests Practice Test / Part 1 #172
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