Global Marine Scanning

Obtaining data with 3D laser scanner

Laser scanning is a widely applicable technology for a number of industries, adoption in the shipbuilding sector is fully exploiting the potential benefits during project execution and for operations and maintenance of existing assets.

The 3D laser scanner allows us to measure any complex construction, regardless of the stage in which the project is located and allows us to considerably improve the quality inspection and the acceptance levels of a product.

Distance measurement

Scanning systems or LIDAR (Laser Imaging Detection and Ranging) mainly capture the physical position of a target object, represented as a series of points (forming a "point cloud"), generally in Cartesian coordinates (XYZ). This is accomplished by comparing the emitted and returned pulse of light, and determining the value of the target object t in relation to the position of the scanning instrument.

The scanner calculates position by measuring the angle of the scanner assembly (scanner head and reflector) and the travel time of light (measured directly as in time-of-flight scanners, or indirectly, as in light-based scanners and in phase).

Color and intensity

The scanner also records a measure of the return energy (represented as an intensity value) from the surface, which is a function of the characteristics of the target surface and ambient light conditions. Most scanners have the ability to determine the color of each dot by using a camera (can be built-in or separate), which is represented by the commonly used RGB (red, green, blue) scale of values. Because scanners are optical systems, only what the scanner can "see" is captured, so the scanners cannot pass through walls or other obstacles (these create "shadows" in the point cloud where no data is captured) . In fact, data integrity is dependent on environmental conditions during acquisition, as is intensity and color data, which vary with light conditions.

Point clouds

Measurement values ​​are represented in a file format that expresses the position, intensity and color of each individual point in the point cloud. Ultimately, the data can be encoded in a variety of point cloud file formats (ASCII, PTS, LAS, E57, etc.), using some variation in the XYZ / RGB position intensity color scheme . Various hardware and software vendors have a proprietary point cloud that can be easily converted based on customer needs. It is often prudent for clients to specify the deliverable file formats based on the end use of the data in negotiation with service providers, especially when the data will be integrated with existing information management systems. Customers may consider using a non-proprietary standard file format such as the ASTM E57 file format for 3D image data exchange to ensure conformance to project needs. Being able to be used by the most common modeling software such as Faro Scene, Autocad, Revit, Archicad, Solidworks, Tekla, Inventor and others.

Measurement accuracy

Several factors affect the accuracy of the point cloud data, including instrument capabilities and calibration, and quality control measures. Environmental conditions that affect data integrity include surface reflectivity, the angle between the scanner and the target (angle of incidence), and the range to the target object (the laser beam diverges with distance, so the measurements further away from the instrument are less accurate). 3D scanning service providers are adept at controlling these sources of error, so it is crucial to establish functional performance requirements prior to field acquisition so that the optimal instrument, scan position (s), and Acquisition times can be negotiated with the service provider to achieve the highest quality deliverables. However, there are a number of general rules that customers should be aware of to ensure proper development of functional performance requirements.