Since the late 1990's, laser scanning also known as laser-surveying has simplified the high capacity gathering and expression of spatial data. Laser scanners measure three-dimensional coordinates across an objects surface automatically, in a systematic manner, at high speed and in near-real time using laser range finding.
Scanning is usually used to measure surfaces and record spatial relationships, but discrete lines, facets and other geometric features can also be extracted from the data using appropriate software. Scanners rely on having line of sight from the instrument to the object, but scans can be performed from multiple positions and combined to record a subject more comprehensively.
How Does Laser Scanning Work?
The first and most vital part of any site capture is the setup of the control network. Whereby, the capturing equipment can be relocated in and around the plant easily and accurately.
The registration markers are placed around the area of interest and surveyed to allow accurate registration of the scanner in 3D space.
The standard markers can be rotated to allow multi directional capture.
The scanner will then be positioned, levelled and set to scan at the required level of detail and quality.
Scans usually take from 3 minutes to 6 minutes depending on the area being captured.
Once the area has been scanned, the point clouds that are created need to be tied together, also known as registration. Each cloud will be geospatially referenced to all of the corresponding clouds using the survey markers and their coordinates. The registration process is carefully monitored for quality and consistency; any in-accuracies are rectified at this point.
Once all of the clouds have been registered, the overlapping data requires consolidating. Where two adjoining scans are used, there will be a degree of repetition resulting in unwanted data. This duplicated data is then removed. Erroneous or out of area information is also removed.