In this post in our series on ‘LEGO Architecture meets BIM‘ we look at how laser scanning can be utilised on projects. For this post I have kindly been assisted by Chris Palmer (BIM / CIM Engineer – Northern Europe) and Shane Dover (Product Design Account Manager UK) from FARO Technologies.
Laser scanning has a number of uses for our everyday projects. For us there are probably 3 uses that we would encounter:
- Using a laser scanner to survey an existing building from which a 3D model or Building Information Model (BIM) can then be produced.
- Using the laser scan output to compare against a 3D model or Building Information Model (BIM) we have already received or produced ourselves prior to receiving a scan.
- Using the laser scan output to compare our model against the final as-built situation to allow the 3D Model / Building Information Model (BIM) to be updated to match.
The uses of these technologies will vary depending on the types of projects, who is commissioning/using the technology and what use case is required. For example a contractor may choose to scan the services above a ceiling as a record of what has been installed before completing the ceilings.
The technology can also be combined with other technologies, for example combining scanning with drones to survey a hazardous area meaning health and safety concerns can be minimised.
LEGO Architecture meets BIM scanning
For this project we have 3 models available to us. We have the Building Information Model (BIM), the 3D printed model (see earlier post on this) and the as-built scenario (the actual LEGO set – more on this in another post).
So to start this process we provided a .STL output of our original authored model from Graphisoft ARCHICAD to FARO. This is the same file that was also used by Hobs Studio to produce the 3D print.
Chris and Shane then visited our office with a highly sophisticated laser scanner. Its called the FARO Edge Arm, which apparently has an accuracy below 100 microns, which in layman’s terms is crazy accurate!! (More details on this piece of kit can be found here) This particular scanner of course would not be used for a building project. The scale here is far far smaller than a typical building project, so the scanner used was a specialist piece of kit normally reserved for scanning engine parts!
The process for scanning is pretty straightforward in that the machine simply points at the area it needs to survey and this data is then fed back directly into the machine and visualised on a laptop screen. What we end up with is a version of the model as a series of millions of points.
Below an image of the scanner, the laptop displaying the results and the two physical models (the 3D print and the as-built).
Image: The laser scanner in action (click to enlarge)
Below you can just about make out the line that is being projected onto the model where the scanner is aiming.
Image: A close up of the laser scanner in action (click to enlarge)
Using this scanner in our office did throw up how sensitive this piece of kit is. The arm was fixed to a desk on a timber floor and the tool pictured up any movement on the floor. Normally this measuring device is permanently fixed in a controlled environment with a concrete floor so you wouldn’t get the deviations we encountered.
Movie: Laser scanning of the as-built LEGO model in action
Now of course scanning by itself is only a step towards creating useful outputs. The scanning process in our LEGO example allows us to compare the two physical models (3D print and as-built) against the computer model (STL file). With this information we can assess how accurate the physical model is compared to the computer model.
The guys at FARO used a piece of software called PolyWorks to compare the physical models against the computer model we produced in ARCHICAD. The sensitivity of the results can be fully adjusted depending on how accurate we want to be. So in the image below you will see items in red which are not fully aligned with the original computer model.
The PolyWorks software allowed us to click on various points in the model and see how comparable the scan was to the model.
Image: PolyWorks comparing the laser scan against the physical model (click to enlarge)
The software then allowed the FARO guys to produce a report, in a very short space of time that could be published as a PDF report. An example of which is shown below.
Image: An example of the PDF output from PolyWorks (click to enlarge)
The laser scanning for our LEGO model did not highlight significant issues with the exception of the base of the 3D print which was slightly larger than the original. However on real projects the ability to survey information from sites is an extremely useful medium. Often though people think that the scan is the end process (some even think this is the model) but it should be clear that the scanning process is just a step between key processes. The technology and tools used by laser scanning companies is highly sophisticated but its outputs, whilst impressive, are largely dumb until you actually put the outputs to good use!
It should be noted of course that there are a variety of providers of technology for 3D measurement as well as companies offering to do the scanning itself. FARO have kindly assisted me here with providing both the technology and completing the scanning.
Rob Jackson, Associate Director, Bond Bryan Digital
FARO is the world’s most trusted source for 3D measurement, imaging and realization technology. The Company develops and markets computer-aided measurement and imaging devices and software. Technology from FARO permits high-precision 3D measurement, imaging and comparison of parts and complex structures within production and quality assurance processes. The devices are used for inspecting components and assemblies, rapid prototyping, documenting large volume spaces or structures in 3D, surveying and construction, as well as for investigation and reconstruction of accident sites or crime scenes.
FARO’s global headquarters are located in Lake Mary, Florida. The Company also has a technology center and manufacturing facility consisting of approximately 90,400 square feet located in Exton, Pennsylvania containing research and development, manufacturing and service operations of our FARO Laser Tracker™ and FARO Cobalt Array 3D Imager product lines. The Company’s European regional headquarters is located in Stuttgart, Germany and its Asia Pacific regional headquarters is located in Singapore. FARO has other offices in the United States, Canada, Mexico, Brazil, Germany, the United Kingdom, France, Spain, Italy, Poland, Turkey, the Netherlands, Switzerland, India, China, Malaysia, Thailand, South Korea, Australia and Japan.
More information is available at: www.faro.com
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