What is the Laser Scanner
In the innovation process that La Sia has undertaken for some years by embracing the BIM methodology throughout the architecture sector, the updating of building survey techniques could not be missing. The company is equipped with a latest generation 3D Laser Scanner station for digital surveying of civil and industrial works using non-invasive techniques.
What is the Laser Scanner
The Laser Scanner is a very high precision direct measurement instrument for the three-dimensional detection of objects. The instrument is able to measure hundreds of thousands of points with very high speed to define the surface of the detected object. The result obtained is a very dense set of spatial coordinates that form the so-called “point cloud”.
The basic principle of the “measurement” of each single point is the difference between the light signal (laser) emitted and the signal received by the machine. Almost all modern laser scanners can be divided into two macro categories depending on the technique used: phase shift based and time of flight (TFT). The first ones use the phase difference between the two signals to locate the distance of the point while the second category uses the time difference between sending and receiving the laser signal.
From the “cloud” to the 3D model
Each time a laser scan (station) is performed, the instrument generates a “point cloud”. At the end of the survey, all the clouds generated using special software will have to be merged. Depending on the complexity of the survey and the degree of detail desired, the number of stations to be performed increases; it goes from 4 or 5 to survey an apartment to over 100 for the external survey of an Outlet as shown below.
Modern laser scanners also mount an HDR digital camera to acquire images of the previously surveyed space. This allows you to “color” each detected point, obtaining a sort of 360° panoramic photo from the scanning point.
The potential of these surveys lies in the fact that each point, being inserted in a precise geometric space characterized by Cartesian coordinates x, y, z, is measurable and with the addition of a georeferenced point the whole model assumes a precise location in the real physical space.
There are many software that can work directly on point clouds to create surfaces, solids, planes, make comparisons between different clouds or with other solid objects (interferences) and create navigable models. The point cloud therefore lends itself as an excellent starting point for the creation of the three-dimensional model. In modern projects for the restoration or expansion of buildings, especially historic ones, the acquisition of the existing building via point cloud cannot be ignored, not so much for the speed of execution of the survey as, above all, for the precision of the model obtained.
Therefore, passing from the point cloud to a 3D model is a linear passage that La Sia has decided to adopt in all projects that envisage a survey of the existing structure. Within the company, the combination of “point cloud” and BIM BIM has become a “must”. With a view to research and development, experiments are also being carried out for the BIM survey and rendering of unconventional “objects” in collaboration with the University of Cagliari.
In addition to surveying in architecture, the laser scanner is also very effective in the field of piping, both in small thermal power plants and in large petrochemical plants; in some cases it is the only tool able to identify changes and modifications undergone by the system.
Conclusions
Also in this sector, the company’s desire for continuous evolution in working methodologies and in instrumentation (hardware and software) has led to huge investments both in economic terms and, above all, in terms of human resources. The company has acquired and trained its personnel, specializing them to use and make the most of these technologies.
