3D laser scanning is the process of collecting coordinates of an object’s surface in all three dimensions (x, y and z) using laser measurements, in an automated manner and at a high rate (up to hundreds of thousands of points per second). Line-of-sight to the object’s surface is required and the initial product is similar to a photograph with depth information. In terrestrial laser scanning this process is realized by an instrument – the laser scanner system.
As the accompanying images show, Seis-Scan’s 3D laser scanners are comprised of four main components. The units are light and compact. When used in the field, they are operated from a tripod or specialized mounts/masts on a pickup truck, SUV or UTV.
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Emits the pulsed laser beam in one direction.
Deflecting Rotating Unit
Directs the laser signal in multiple directions over a smooth arc, using a rotating polygon mirror and by rotating the scanner’s body.
Detects the returned signal and processes the information to determine distance, angle and 3D coordinates (i.e., north, east, elevation).
Control Data Recording
Sends scanning orders to the laser unit, and stores the scan data. This component can be separate from the scanner body, in a data collector or notebook computer, or integrated into the scanner system.
The key technical parameters of commercially available laser scanner systems comprise:
A single session of data collection at a particular location (one origin and one orientation) is called a scan. The resulting collection of points with 3D coordinates is called a point cloud. Additional information at each point may also include colour from the digital camera and reflectivity. In most cases multiple scans are necessary to capture the target object’s entire surface.
The next step is registration or alignment and geo-referencing, the process of transforming each point cloud into a common coordinate system. The resulting data set can now be viewed, manipulated, analyzed and modelled to produce and extract digital information, 3D renderings and 2D drawings. These extensive deliverables go far beyond what is produced in a traditional survey, creating numerous applications in many sectors.