Using satellite sensors to quantify components of the biosphere and their activity is now well established. A news story last year used ground survey to validate a new estimate of the global tree population, which leads to questions about how changing age distribution and morphology may affect future ecosystem function. Lidar has been much talked about as a way to remotely examine and quantify the architecture of at least tree canopies. Alex looked into how the technology has advanced in ecology and also how it has been used more generally.
Shining a new light on our 3D world
Visualising the earth by harnessing the electromagnetic spectrum we know matter emits, reflects, transmits and absorbs. Remote sensing (RS) technologies bring major advantages over ground-based science: global coverage, single instruments and procedures, continuous measurements, for example. Light detection and ranging (Lidar) is an active RS technology. The RS platform emits light energy in short pulses to measure physical properties of the Earth’s surface and atmosphere based on illumination and reflection. The length of time between the lidar pulse and returning echo is equivalent to distance to the target. This information can provide the building blocks for 3D models of surfaces across the globe to high spatial resolution. The strength of the echo (amount of returning light) can be related to concentration, for example, the concentration of air molecules in a column of atmosphere below. This example can go one step further in its analysis and separate the returning echoes according to the calculated distance from the sensor. Atmospheric density at any given point in the column is therefore attainable. This is only the tip of the iceberg when it comes to current Lidar applications ranging from meteorological measures of cloud cover to mapping geomorphology of entire landscapes.
Novel applications of Lidar that I bet you didn’t know about…
Google’s self-driving car makes use of a Lidar comprising of 64 lasers to position itself within the urban environment. Crash prevention is of key importance and relies entirely on locating surrounding 3D structures.
Radiohead produced the first music video (house of cards) constructed entirely using geometric informatics systems and Lidar scanning systems to map people and environments in 3D.
Lost City in Honduras found! Even archaeologists use it. There is an ongoing race against time in Honduras to seek out buried ruins now threatened by deforestation. “Lidar is able to map the ground even through dense rain forest, delineating any archaeological features that might be present” (National Geographic, 2015). The discovery of the City of the Monkey God has no doubt fuelled further excitement surrounding Lidar!