SCAN to BIM: OFFICE BUILDING DIGITALIZATION
SCAN to BIM: OFFICE BUILDING DIGITALIZATION IN THE CENTER OF BARCELONA
The object of project was to use 3D laser scanning technology to build an accurate BIM model from the point cloud of the building. Laser scanning for BIM modelling is the fastest and most accurate method for delivering As-Built models. It is widely used for refurbishment, renovation and/or rehabilitation projects and for the maintenance phase of the building.
CONRENTRAMWAY acquired the building that had been inactive for six years on this plot in the centre of Barcelona. They decided to carry out a renovation project and they needed to have the current state of the building. The rise of new technologies and the increase in projects with BIM methodology made the property decide to create a digital survey of the building. CiTD was the company in charge of the construction of this
digital model in BIM. The renovation project is being carried out by Batlle i Roig Arquitectes, a renowned architecture studio in Barcelona.
The digitization of the building was planned in four phases: initial project study, scanning, processing and generation of point cloud and modelling.
Initial project study
The building is located between Avenida del Paralelo and calle de Vila i Vilà, a block named Jardines de las Tres Chimeneas, very close to the Plaza de las Dársenas.
The building is formed by two differentiated volumes, tower building and lake building, joined by a footbridge in its first and second floors. The tower building, in turn, has two heights, S+B+4 on the façade facing the street Vila i Vilà and S+B+11 on the façade facing the Avenida del Paralelo. The lake building has S+B+4. Both buildings share a basement floor. The total surface area of the building is 30,164 m².
Once the characteristics of the site and the architecture, both exterior and interior were studied, a planning was made of what equipment and how many scan points were necessary to complete the entire surface of the building. The better the point cloud is defined, the higher the quality of the model is. It must keep in mind that this model is the starting point for the renovation project that will be carried out by Batlle i Roig. Therefore, it had to be as precise as possible to the current state.
TOPCON provided the laser scanning equipment. In order to do the job, two TOPCON laser scan were chosen, model GLS-2000, with extendable tripods on wheels and targets.
Point cloud generation and processing
Two members of CiTD were in charge of going through the building to perform the scans while a third person was in charge of the point clouds generation. The rest stops were used to dump the data recorded by the laser scanner to the computer. In this way, scan points could be discarded and/or added depending on the results seen as the point cloud was generated. A lot of time is optimized and planned points are corrected in the office.
The software used for data processing was JRC 3DReconstructor provided by TOPCON and Autodesk Recap to facilitate subsequent modelling in Autodesk Revit. It is recommended that the scan points are correctly recorded in a drawing so that the subsequent processing work is fast and error-free.
Once we had the point cloud processed in Autodesk Recap .rcp format, we inserted it into our Revit model according to the UTM coordinates of the plan in CAD .dwg format provided by the architecture studio. It also gave us a list of information requirements that the model should have, such as classification parameters of elements, nomenclature of Revit types and families, name of subprojects (worksets), etc.
The elements represented in the point cloud (generally the finishes, such as technical floors, false ceilings, wall coverings, etc.) were modelled with the actual material and colour built, while the hidden elements (such as partition walls, slabs and other structural elements not seen) were modelled with default material and colour.
A plan-by-plan of the theoretical location of the laser scanners was made to calculate how much time was needed to get the job done.
The TOPCON specialist trained the CiTD team on the operation of the equipment, especially in the information processing software for each scanning point. Besides the scans, other supporting data was taken that a point cloud cannot collect, such as distances and thicknesses hidden in false ceilings, technical floors, forged, among others.
Autodesk Navisworks was used to review modelling and perform quality checks.