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According to the National BIM Standard Project Committee in the United States, "BIM is a digital representation of the physical and functional characteristics of a facility. It is a shared knowledge resource of information about a structure, forming a reliable basis for decision making. BIM is in other words defined as existing from earliest design to demolition." This definition and BIM practices are critical to understanding and achieving Scan To BIM.
Scan To BIM is an as-built survey process using lasergrammetry or photogrammetry that captures information about the scanned environment. The surveying device digitizes the 3D information and data into millions of points which, when assembled, form point clouds. The point clouds are processed, exploited and analyzed to support the BIM (Building Information Modeling) process, which consists of creating a 3D digital model from the capture of reality and the point clouds. In addition to the modeling of the existing physical space, 3D models can be added in order to anticipate and simulate the modifications to be made to the building as built.
The Scan To BIM workflow
The use of 3D laser scanners
3D scanners are advanced technologies that are designed to improve, facilitate and accelerate the survey phase in the field. This is how the term 3D surveying came about, as traditional methods of measuring information were too inaccurate and labor intensive both in the field and at the computer. The scanners project a laser in all directions around its axis, while rotating on itself to be able to take all the information of the environment present around it. It takes into account all the more or less complex structure of its environment to be able to deliver them in the form of clouds of points exploitable for the 3D modeling and the BIM approach.
During the 3D survey, the scanners digitize the "as-built" information which is then delivered to scanning software such as ReCAP in order to assemble the scans and obtain a complete point cloud. This assembly phase is called registration(click here to read the article on scan assembly).
Point cloud to BIM
The point cloud is an information dissemination system that maps a physical space and represents the modelable digital twin of an object or environment that the 3D laser scanner has surveyed. It gives visibility on the project in progress even before bringing details thanks to the 3D modeling. It is a gain of time, efficiency and speed that facilitates the coordination and the realization of the project, while reducing the margin of error that a surveyor or an architect can perceive by taking his measurements on site. Point clouds serve as a solid foundation for the creation of 3D BIM models and digital mock-ups. After their assembly, the point clouds can be processed, exploited and analyzed thanks to software or platforms such as ATIS.cloud which will allow the users to visualize the information captured from the 3D survey, to process the 3D data and to share them using advanced tools in order to work on the point cloud. This step is essential to accelerate the 3D modeling, the measurements, annotations and project information being referenced and centralized on a secure online platform.
Subsequently, the point clouds (or part of the point clouds that need to be modeled), are exported to design software (CAD software such as ArchiCAD, AutoCAD, Revit) in order to be able to, with the help of the information provided by the point cloud, create a 3D model. The BIM is now in most advanced countries a standardized planning method that complies with the standards of construction, design, renovation and is in some cases imposed to AEC companies or strongly recommended. All the steps of Scan To BIM promote collaboration between the stakeholders of a project and everyone can modify, update and extract information from the BIM model.
Finally, a BIM model is an assembly of geometric objects from a database established as a 3D model is created. It is therefore necessary to be able to define the level of detail of the components of the structure in order to establish a common reference system between the actors of the construction. These levels of details (Level Of Details LOD) are included on a scale ranging from 100 to 500 depending on the accuracy of the structure of a 3D model. LOD 100 is a level of detail that represents little or nothing of the object as built (a cube to represent a house or the slope of the roof may not be modeled. LOD 500 is on the contrary a level of precise details where we will model the presence of all the bolts on a network of pipes or steel in reinforced concrete.
Scan To BIM issues
The problems that Scan To BIM can solve
Collecting data from a structure or environment is very complicated and requires a lot of time, precision and organization. Getting to an environment is not always an easy task. Indeed, the access to the site is sometimes laborious and the taking of measurements of the structure is a long process and the presence of natural or artificial obstacles can slow down the collection of information or even prevent it. All these conditions must be taken into account and are issues that affect time, budget and human or technological resources. The Scan To BIM technology is a new working method that, through the 3D survey phase, allows to capture a maximum of extremely precise information, quickly and to deliver the data collection in the form of point clouds, visualizable on a computer.
The documentation of the building as built is often obsolete or fragmented or both. Moreover, it is regularly updated by processing and exploiting data in point clouds or 3D models. The Scan To BIM approach facilitates the follow-up of modifications and simulations in order to create a coherent and relevant BIM model. These updates and modifications can be viewed and interpreted by all users of the BIM model who collaborate on a project as a team.
The benefits of the Scan To BIM approach
The most notable advantage is that modeling and project planning errors are reduced. These potential errors are avoided thanks to an optimal and precise collection of information and data from the environment, but also thanks to the superposition of the 3D model and the point cloud, in order to increase the quality level of the modeling.
Secondly, Scan To BIM provides a much-needed quality of work for AEC, as every step of the modeling and progress of a project is shared with stakeholders. Site inspectors reduce their travel without losing visibility and understanding of the project. Access to construction or renovation sites is easier because the manpower employed is reduced and measurement is facilitated, especially if the environment reveals obstacles that hinder information collection and make it difficult to see the structure's components.
Finally, property managers can anticipate the implementation of development work more easily. The 3D digitization and processing of point clouds makes it possible to visualize the entire structure of a building and the electrical and mechanical systems that make it up. It is then easier to plan insulation work to reduce their carbon footprint, to organize and simulate the layout of furniture according to the electrical and mechanical systems.
Scan To BIM is becoming an easier-to-access standard for AEC firms thanks to technological developments regarding point clouds. The Scan To BIM approach is also a major factor in the progression of the BIM process which is increasing its use in construction projects. Cost reduction, time saving, easy access to site data and stakeholder collaboration are significant benefits of Scan To BIM which are essential to stand out in a competitive market.
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