Lidar

Definition

Lidar, an acronym for Light Detection And Ranging, is an active remote sensing method that uses light in the form of a pulsed laser to measure distances to the Earth. These light pulses, combined with other data recorded by the airborne system, generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.

What is Lidar?

Lidar technology has the ability to capture high-resolution geospatial data and has applications in various fields such as meteorology, geology, seismology, and environmental study. In distinguishing between objects, lidar uses ultraviolet, visible, or near infrared light from lasers. The technology works day and night, regardless of whether the Sun is present, as it relies on an active illumination source - a significant advantage over relying solely on sunlight.

A typical lidar system includes a laser, a scanner, and a specialized GPS receiver. Airplanes and helicopters are the most commonly used platforms for acquiring lidar data over broad areas. Two forms of lidar are commonly used: Topographic, which predominantly uses near-infrared light to detect the Earth’s land, and Bathymetric, which uses water-penetrating green light to also measure seafloor and riverbed elevations.

FAQs

What is the primary use of lidar technology?

The primary use of lidar is to create high-resolution maps, with applications in geodesy, geomatics, archaeology, geography, geology, geomorphology, seismology, forestry, atmospheric physics, laser guidance, and airborne laser swath mapping. It is also used in control and navigation for some autonomous vehicles.

How accurate is lidar?

Lidar system accuracy is highly dependent on factors like flight height and speed, atmospheric conditions, and the quality of the ground control points used. However, lidar data is generally considered to be highly accurate, often yielding positional accuracy of several centimeters both horizontally and vertically.

Why is lidar a preferred method of data acquisition compared to traditional methods?

Lidar is often preferred over traditional methods of surveying due to its ability to penetrate dense vegetation and capture surface information beneath, production of high-resolution maps of topography, vegetation structure, and buildings. It also captures massive amounts of data points quickly and accurately, saving time and resources.

Does lidar work under all weather conditions?

Weather conditions can impact the efficiency and accuracy of lidar data acquisition. Rain, fog, and high winds can scatter light beams and reduce the accuracy and quality of data. However, lidar mapping can be done at night and during cloudy conditions, a key difference from photogrammetry which is reliant on daylight.