Better accuracy, speed in on-site data acquisition for Building Information Modeling

By Niraj M Wanikar, Chief Editor, CNCTimes.com, 2016-09-29 15:43:00

Building Information modelling (BIM), as a concept, first came about in the 1970s, but its methods have been refined considerably since then. Widely used by city planners, architects, and civil engineers today, BIM enables stakeholders to better make high-impact decisions by providing timely, relevant information.

According to the National BIM Standard-United States 1, BIM is a digital representation of physical and functional characteristics of a facility, shared as a knowledge resource to form a reliable basis for decisions during its life-cycle, which is defined as existing from earliest conception to demolition.
BIM facilitates the collaborative process of designing a building, putting varied types of information all on one coherent system of computer models, as opposed to separate sets of drawings. More than just geometry, BIM covers spatial relationships, light analysis, geographic information, and quantities or properties of building components. Today, a typical BIM file contains data that extends all the way to the ‘seventh dimension’.

This includes the basic, traditional two-dimensional technical design drawings of buildings; three-dimensional (width, height, and depth) spatial drawings; ‘fourth dimension’ of time (4D BIM); ‘fifth dimension’ of cost (5D BIM); ‘sixth dimension’ of sustainability (6D BIM); and ‘seventh dimension’ of facilities management (7D BIM).

Apart from its ability to collate discrete sets of information, BIM allows data to be updated in real-time, which means various stakeholders will have instant and common access to the latest information. Simply by being on the same page, companies have avoided costly mistakes of error and rework, and also enjoyed enormous benefits of time-savings and greater levels of accuracy in estimation.

Laser Scanning Technology in BIM
As the usage of BIM evolved over the last two decades, the user community has found laser scanning technology to be useful in numerous applications.
The capabilities of a modern day laser scanner have contributed much richness and texture to the information included in BIM files for architects, contractors, facility managers, and owners.

Laser scanning solutions from 3D measurement device manufacturers such as FARO have shaped the way teams work together, making it easier for them to communicate, collaborate, and solve problems that may crop up in the course of a project. Overall, such BIM solutions have resulted in high-quality projects and enabled teams to complete them in a shorter time, and at a lower cost.

In practice, FARO’s laser scanning solutions are used by BIM specialists for site documentation purposes, right from a facility’s structural design phase to its post-construction architectural phase. Laser scanning technology captures existing conditions in 3D within minutes, at the touch of a button. With the data, users can create 2D drawings, conduct inspections, create 3D building modelling, and even generate site plans that are registered to global positioning coordinates. Practitioners are preferring laser scanners over traditional tools such as total stations, because laser scanners provide them with much more detail and data points, which have proven useful when generating final deliverables of a project.

With laser scanning technology, architects can now work off real-time 3D data on their computers with much less effort – conjuring designs, manipulating drawings, or adding elevations – and all without compromising on measurement accuracies.

Sample Scan Result
A quick comparison of the conventional surveying equipment and the laser scanning technology reveal that the modern laser scanner provides several advantages over traditional tools. Whether in terms of speed, scan detail, or flexibility of data output, the FARO Laser Scanner as an example surpasses the conventional equipment choice of a total station. With laser scanning technology, BIM specialists complete surveying tasks much more quickly and obtain reports with more information (e.g. resolution, position, and color).

In fact, with FARO’s complete laser scanning solution, practitioners can achieve better efficiency and effectiveness with an improved workflow for 3D documentation in three simple steps – Scan, Process, and Deliver.

BIM Applications of Laser Scanning Technology
Many of today’s building and infrastructure projects lack in as-built documentation of the existing facility, and 2D plans or existing drawings are rarely available for old buildings. The presence of this issue has made it challenging for planning and redesigning works to take place. In addition, the conventional total station is inadequate for capturing physical structures efficiently, since it can only capture a few points at a time. Not only is the method time- and labor-intensive, the data obtained would be incompatible with a point cloud processing software, limiting the possibilities of its usage.

3D documentation solutions like the FARO ® Focus 3D X Series and FARO ® Scanner Freestyle 3D would, however, be capable of addressing the need of digitization for BIM practitioners. This proven workflow has enabled users to digitize physical structures easily, save costs by eliminating rework, and keep projects on schedule.
FARO’s selection of software (e.g. VirtuSurv, PointSense, and SCENE), further simplify and streamline the process for users.
2D drawings can be created with line fitting and building specific tools in the PointSense Building software.

Structural Inspection
Structural damage to buildings can cause substantial economic losses to property owners, and can also reduce a property’s current and future value. Structural inspections enable owners to take preventative measures or to make necessary rectifications.

With traditional surveying tools, data capture for structural inspection is slow and inflexible. Moreover, the extent of damage cannot be monitored with certainty, and the evidence is documented only in 2D images. On the other hand, FARO Focus 3D can provide the information required for an effective assessment. For instance, an analysis of concrete floors for slab flatness will indicate if any area needs to be adjusted, after which the BIM specialist can determine the volume of material needed for that job –resulting in less wastage and a better cost management process overall.

In addition, laser scanning technology can also be used to verify that components of a building have been installed according to its original design, which is helpful for cost management, insurance claims, or legal disputes. The FARO Focus 3D can perform as-built documentation with millimeter-accuracy (±2mm), capturing details such as pipes, HVAC systems, structural steel, floors, and even rebar in concrete slabs throughout a building. If any discrepancies are observed when compared against a design, property owners can either make alterations or rectifications as necessary.

3D Building Information Modelling
Contractors of building and infrastructure projects often do not keep a record of current construction or maintenance documents of the existing facility. Yet, to acquire digital survey data of a large space by utilizing conventional methods would be too time-consuming and laborious. In any case, the incompatibility of the data acquired would have made it difficult for the team to import the information into any of the popular CAD programs available in the market.

In a similar fashion to which 2D drawings can be generated from the scans obtained by FARO Focus 3D, producing 3D building information modelling is also a breeze with FARO 3D documentation solutions. The FARO VirtuSurv software acts as a flexible interface to allow users to import and export scan data for use on various platforms. The FARO PointSense Building software, an AutoCAD plug-in, then efficiently processes the 3D scan data with a range of available tools, which allows a user to manipulate the information for specific project deliverables.
Laser scanning technology enables a reduction in design man hours with automated tools (e.g. wall alignment and wall fitting tool) when creating building models.
An example of a 3D building model created with PointSense Revit through post-processing of the point cloud data.

Success Stories of FARO Customers

On-site 3D Building Model Creation Made Easy
Third Building Construction Company of China Construction Eighth Engineering Division (CSCEC83) is one of the biggest building contractors in China. The company has been involved in building projects for a variety of uses, including aviation and aerospace, sports venues, super high-rise buildings, municipal mass transit, environmental protection and water resources, urban complexes, commercial and office buildings, industrial factories, as well as medical and health facilities.

In 2014, CSCEC83 embarked on a new project to construct the Jiangsu Grand Theatre and to complete the handover by June 2016. Given the large scope of the project (a total net land area of 196,633 m 2, and total construction area of 271,386 m 2), to say that the team was hard pressed for time was an understatement. The unique design of the theatre further added to the complexity of the project in terms of quality control.

Previously, the team was using the Electronic Total Station (ETS) to test the accuracy of abnormally shaped structures by comparing structural key points. Due to the limited numbers of data points collected, the test results were inherently incomplete and unreliable. Coupled with the complex double curved surfaces on the water droplet structures, it was practically impossible for the team to achieve proper, accurate results using the ETS.

To overcome this immense challenge, the team decided to use the FARO Focus 3D X 330. FARO Focus 3D X 330 could effortlessly scan the entire curved surface and provide the team with the necessary data, thus resolving the quality control issue.
In conducting the structural testing of curved surfaces of the water droplets, the Focus 3D X 330 was first used to collect the point cloud data. Next, the FARO SCENE software was used to integrate the scan data, followed by a comparison with the architectural design model on the Geomagic ® software to check that the various design requirements were met.

This entire process was not only fast, it was also highly accurate. A job that used to take an entire week or more was instead accomplished in just two days with the Focus 3D X 330, which brought vast improvement to CSCEC83’s productivity.

Simplifying Structural Deformation Monitoring
Beijing Urban Construction Exploration & Surveying Design Research Institute (Beijing Urban) undertakes projects involving railway construction and detection (or monitoring) of tunnel deformation, providing independent appraisals that contribute to the safety of civil engineering projects.
There were several limitations with Beijing Urban’s older methods of data acquisition. For one, performing measurements was dreadfully time-consuming, requiring up to 8 hours for just data collection (excluding processing and analysis).

In addition, data collected with total stations was inaccurate as they were only able to register a limited number of points. The team had to rely on software to extrapolate extensively and to connect the dots so as to form any shape. For this reason, crucial data points that would indicate instability or deformation often went undetected.
With the Focus 3D, Beijing Urban managed to improve on both its productivity and accuracy. The team is now also able to generate better reports for its customers, including tunnel cross-sections, histograms, and 3D model outputs. For a job that used to take 8 man hours, Beijing Urban now requires just 3 to 4 hours to complete. Additionally, Beijing Urban also benefited from the portability offered by the Focus 3D.

With a size of only 24 x 20 x 10 cm and weighing just 5.0 kg, the Focus 3D was an enabler of convenience that the team welcomed. As a standalone solution, the device did not require external devices to operate, eliminating the need to transport any extra equipment to the scanning location.
Evidently, the investment increased the company’s productivity by leaps and bounds, and added much more detail and richness to the data acquisition process.

Acquiring Accurate Measurements of Harsh Mechanical Rooms Safely, Quickly
Air conditioning equipment (including boiler, chiller, air handling unit, and heat exchanger) for a building is usually located in a dedicated space known as the mechanical room. The interior of a mechanical room can get rather hot and noisy while the equipment is in operation. In such a harsh environment, a person can only work at full concentration levels for about an hour. Consequently, workers who are deployed to the mechanical room – to take measurements of dimensions and existing equipment required for construction drawings – need frequent breaks in order to work effectively.

Hibiya Engineering Ltd is a company that provides engineering services – including air conditioning, water supply, drainage and sanitation, electricity, as well as information and communication technology services – to building owners. At the end of 2011, Hibiya Engineering invested in a FARO Laser Scanner Focus 3D to facilitate the measurement of existing facilities. Using this new device, it takes the team only an hour to measure existing facilities that are due for renovation, with a measurement process that is significantly simpler.

For Hibiya Engineering, the critical factor in choosing the FARO Focus 3D was its economical price point. Apart from that, the accompanying point cloud data processing software, FARO SCENE, and the device’s portability stood out to the team. The FARO Focus 3D’s small form and weight made it extremely suitable for taking multiple measurements in a narrow space, requiring minimal manpower.
Since introducing the FARO Focus 3D, Hibiya Engineering has enjoyed several improvements to the renovation process of air conditioning facilities. Using the new device, the company requires only a handful of workers to obtain high-quality measurements safely and within a short time period. Working at heights has also become a thing of the past, because Hibiya Engineering no longer has to rely on manual methods to take measurements, which would have required scaffolding for workers to access hard-to- reach areas. The FARO Focus 3D eliminated such needs almost completely, making working conditions much safer for the engineers.

Moreover, the device also reduced the need for any rework, saving Hibiya Engineering precious time on projects. In the past, when the team relied on hand tools and paper records, it was common for engineers to revisit a site to repeat measurements because figures did not match up at times. However, with the FARO Focus 3D, engineers can ‘revisit’ the point cloud data on the computer as often as required, without having to physically return to the equipment room.

As Hibiya Engineering adopted FARO Focus 3D into its workflow, Building Information Modeling (BIM) replaced traditional drawings, enabling the team to virtually design and build a 3D model of any given facility on the computer.
Using point cloud data collected by the FARO Focus 3D, the engineers create a BIM model of the current set-up of the mechanical room with CADWe’ll

Based on the 3D model, the team prepared the plan and design for the renovation accordingly.
With the walkthrough feature, the team can view the space as though renovation had been completed, even before the work begins. In fact, the BIM model allows all parties involved in the renovation (e.g. client, subcontractors) to better understand the work plan, facilitating the entire process from start to finish.

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