Lidar

 Lidar instruments shoot millions of laser pulses per second, which bounce off a surface or object to measure distances and directions to the object. 

You would think that this affects humans on the specified area?

Using the known speed of light, we can figure out how far away any object is by measuring how long it took for the laser to leave our instrument, hit the object, and bounce back to the instrument. We can also tell something about the composition of objects or the surface that the laser bounced off because different types of materials absorb different amounts of laser light energy. By looking at the strength, or intensity of the light that bounces back, we can distinguish pavement from grass, and sand from water.

By shining lasers at targets from different angles, lidar can create detail-rich, 3-dimensional collections of data points. These “point clouds” can then be processed to create digital elevation models (DEMs) of the Earth’s surface that are accurate enough to determine which way water flows and can be used by researchers and decision makers to understand and predict environmental changes such as stream levels or flooding.

With a camera added to the system, imagery can be combined with the lidar data to create immersive, 3D, photo-realistic, digital environments that can be explored, measured, and interacted with on a browser, on a laptop or cell phone, or using a virtual reality headset.

This system works well when the instrument stays in one place, but it gets more complex when you want to move the instrument to collect data across larger areas. This is where GPS, or the Global Positioning System comes in. By pairing a GPS receiver with a lidar unit, we can compute precise coordinates for where the instrument was when a particular laser pulse was sent, and where the instrument was when it received the same pulse after it bounced back from the target. This makes it possible for lidar units to be mounted on vehicles in the air, on the ground, or on the water, and collect important data in many different environments and for many different purposes.

Surveying and mapping professionals use lidar and GPS every day to digitally capture geospatial data. At construction sites, surveyors use aerial and ground-based lidar and GPS before, during, and after construction. They collect high-precision data to inform each building phase of a project and provide “as-built” information to manage a site once construction is complete. Lidar units mounted on cars and trucks map roads, highways, signs, hydrants, phone and light poles, and other transportation infrastructure