What are the different types of laser scanner used by PEGS?

PEGS primarily uses two types of laser scanner, they are Time of Flight & Phase Based laser scanners. Phase based scanners are used for short distance scanning whereas Time of Flight scanners are used for long distance scanning, mainly for Civil & other infrastructure applications.

What is a Phase Based Scanner?

The principle of a phase based scanner involves the emission of a laser rays at a specific frequency, and the recording of the reflection of this wave, which will be “shifted” or “displaced” by its impact on a reflective surface. The displacement of the reflected wave allows the precise calculation of the distance between the point of impact and the scanner. Phase-shift scanners are faster and more accurate than time-of-flight scanners.

What is a Time of Flight Scanner?

The principle of a time-of-flight scanner involves the emission of a light pulse and the recording of the reflection time of this light pulse. As the speed of light in air is known, the micro program of the device calculates the distance between the scanned surface and the scanner. Time-of-flight scanners allow scanning over longer distances (up to 2 km) than phase-shift scanners (up to 80 meters).

How are the scans colored?

PEGS uses a Leica Nodal Ninja Kit to capture 360° panorama images and later the images are linked to individual scan worlds to generate colored point cloud data.

Is laser used by Laser Scanners are eye-safe?

Although a laser will always pose a potential hazard to the retina, the use of scanners in practice and their speed of measurement are such that this risk is virtually non-existent. Standards are used for the classification of lasers by numerous factors, including their power. The lasers (Class 2 or 3R) used in 3D scanners are of the low power type, and do not require the use of any specific protective equipment. However, it is inadvisable to stare at the laser with eyes wide open for a period of several minutes... given the speed of movement of the beam, this would be difficult in any case!

What are the different stages of a laser scanning project?

The first step to perform a laser scanner is to perform laser scanning survey in the field, a dimension control survey is also performed along with this to maintain registration accuracy. Once the scanning in the field is finished the scans are registered using the points of dimension control survey.

The registered point cloud data is then processed using various software’s depending upon the client’s requirement for deliverables.

What kind accuracy can be expected from a laser scanning project?

PFor laser scanning in the plant engineering environment +/- 2mm accuracy can be achieved easily where as for civil applications the accuracy ranges between +/-8mm to +/-12mm.

What are the usages of Point cloud data?

A point cloud can be used for the following:

  • Measure dimensions between two items of equipment (clearance, ceiling clearance) or on the equipment itself (pipe diameter, door width, corner angles)
  • The remote visualization of a site or structure (in case of a remote installation, intermittent opening, a site in service or which is difficult to access).
  • Detection of non-conformities in a theoretical model (project) in relation to the actual situation represented by the point cloud (on an old site or a new site immediately prior to turnkey delivery)
  • Simulation of the installation of new hardware (equipment, piping, extension) in an existing environment.
  • The conduct of certain analyses associated with risk management (radioactivity, noise, explosion, run-off, retention capacity, etc.)

How big are the files?

A raw scan file can be as big as several gigabytes but these points are processed and the scans are registered together. The raw data from a laser scanning project with 30-35 scans will be in a range of 4-5 GB.