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Caserta Document Center: BIM model restitution through laser scanner survey
Torrita di Siena church: mapping deterioration through laser scanner survey
Historic Palace in Rome: BIM model restitution through laser scanner survey
Efficient management of real estate assets (even small ones) today requires the use of relational databases that coordinate, in addition to normal economic management, all technical (especially predictive) property maintenance. Documentation production, economic management, and facility management of each building can be encapsulated in a single BIM model (oH-BIM) that allows for complete management control and a consequent improvement in workflow efficiency.
The creation of an accurate and effective BIM model requires an equally accurate and effective survey; the Laser Scanner survey provides an extremely accurate three-dimensional model of the property very quickly. This model (point cloud) will implement and integrate the BIM flow allowing to work on a certain and accurate basis of reality.
The first fundamental step in the preventive diagnostic process of a building structure is the observation of its geometry (internal and external) through the use of tools that also allow precise point survey through digital images (laserscanners).
This is done to define at time 0 (T0) the geometry to be analyzed and will be the basic reference for the control over time of the structural organism.
Especially for Cultural Heritage, the importance of monitoring is well highlighted in the D.M.14 January2008: “Guidelines for the evaluation and reduction of seismic risk of cultural heritage aligned with the new Technical Standards for Construction”,in paragraph 4.1.9: “The periodic monitoring of the building is the main tool for a conscious conservation,as it allows to plan maintenance and implement in time, when really necessary, repair work, in case of structural damage, and consolidation, aimed at prevention.
Geometric control of the construction can be performed by topographic,photogrammetric surveying procedures,or by using innovative techniques,such as point cloud generated by laser scanner
By means of the first mapping of the building, it is possible to identify both the overall geometry of the organism and that of the building elements, also taking into account the state of preservation of the materials. In thisfirst phase of survey, taking into account the high degree of detail that the Laser Scanner can have even at great heights (the range of the scans is 120 mt and the maximum resolution is 0.8mm@10mt), it may be possible to identify and map the instabilities (inactive or stabilized), through the identification of the cracking frameworks and damage mechanisms.
In fact, with laser scanner survey technology, it is possible to locate major lesions on all investigated elements, and report them on the elements using laser orthophotos. Surveying with laser scanner technology is also particularly suitable for archaeological sites for checking the variation of the geometric arrangement of architectural and structural elements: deviations from the vertical(out of plumb), distortions. This technique effectively prevents dangerous subsidence or collapse.
The Laser Scanner is a very high-precision direct measurement tool for three-dimensional object detection.
The instrument can measure hundreds of thousands of points with a 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 principle behind the “measurement” of each individual 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 i mplanted technique: phase shift-based (Phase shift) and time-of-flight (TFT). The former use the phase difference between the two signals to find the distance to the point while the latter category uses the time difference between sending and receiving the laser signal
