When we think of lasers we tend to think of medical uses – like laser eye surgery, laser hair removal and other procedures. We may also immediately visualize that laser pointer we have for business presentations or the last light show we watched at a concert. However, lasers have a plethora of applications that include everything from barcode scanners to space flight, and even construction industry uses. In addition to basic surveying equipment, lasers can assist in all stages of design and construction – from conception to post-build.
3-D laser scanning is a non-invasive, non-destructive technology that captures the shape and appearance of existing physical objects using a line of laser light.It creates a digital point cloud from the gathered data that can be used to create models, schematics, and preserve “images” of existing conditions. The best part is that it’s much simpler than traditional surveying and documentation techniques, as the lasers do not need to physically touch a surface to measure it.
As a digital record, its method of capturing is also very similar to a camera in the sense that the laser cannot see through or behind objects. To map something like the existing features of a building, it can take anywhere from15 to 100 scans, depending on how full the space is of walls, inventory, equipment, and debris. If objects obstruct the laser’s view, then additional scans from new positions must be taken to composite the full view.
“It’s not X-ray vision,” Joshua Cohn, BIM manager at NewSouth Construction in Atlanta, GA told Construction Dive, “Although when you see it at the end of the day, you can see everything.”
Using rangefinders and moving mirrors to position the laser beams, the laser scanning systems can determine the distance of an object and it’s positioning from long distances, although accuracy tends to break down dramatically at distances near two kilometers.
The scanning motion is usually controlled by a software system that also tabulates the measured and collected data. The ability of laser beams to stay narrow and focused even over great distances, known as collimation, enables very detailed and precise measurements that weren’t attainable prior to the advent of this innovative technology.
As a design and construction tool, laser scanning has numerous uses. Most notably, laser scanning creates a three-dimensional blueprint of the existing space and building conditions with ease. Beyond that, it’s especially useful in renovation projects without pre-existing records. By scanning the space, one can create accurate, as-built records to start from before retrofitting and refurbishing can take place.
“You have your existing conditions, which you’re renovating,”Cohn said, “and you want to find out what structure was there, what HVAC was there, all of the existing components that you’re trying to connect or tie into or coordinate with.”
Structures, walls, and other features may have been added or subtracted over time. Digital laser scanning helps construction teams when existing builds and structures do not match the architectural blueprints for a building. Traditionally, as-built were compiled using a combination of blueprints, old drawings, un-scaled PDFs, time consuming field measurements and good old-fashioned guessing. However, as this technology becomes more widespread, the problem of nonexistent or less-than accurate as-built records will quickly become a thing of the past, as laser scanning is especially useful when it comes to documenting the construction process and creating a comprehensive as-built map.
Laser scanning is used to take digital snapshots in order to preserve a record of project milestones that subsequent work will hide – like the amount of rebar a contractor used before a concrete pour or the placement of plumbing and vents. This allows for the collection of valuable information potentially helpful to subsequent designers and builders, provides a higher level of quality control, and ensures
greater understanding of the details within a finished building. 3-D scanning can also aid in spotting early stage costly mistakes – avoiding reconstructions and teardowns if they become permanent and harder to fix.
At all stages of construction, from design to completion, a laser scanner is a powerful tool for analyzing the existing conditions of a potential construction site. Compared to standard survey techniques that produce topography and feature locations alone, scanning provides greater detail, verification and a unique visualization option to help designers get more complete picture of the site.
Existing condition scanning is used to produce a true-to life representation of a project’s starting point. Its existing structure, topography quantification, building tie-in, and remodel or interior projects, are all examples of data that can be scanned and collected at this stage. This stage of scanning helps map existing conditions in high resolution, identify any errors compared to 2-D as-built docs, reduce client risk for renovation and rehab projects, and reduce the need for cumbersome physical site visits and inspections.
Mid-construction scanning is useful at various stages to check progress, verify standards compliance, and obtain valuable information in preparation of future phases of construction. Interior construction projects are scanned at various stages and a virtual 3-D model of the site isprepared. The model can be compared against the design and used to manage mechanical, electrical, and plumbing(MEP) aspects of construction – especially useful when working with prefabricated elements. The mid-constructions can help monitor all structural design and construction aspects of the build.
Other useful aspects of 3-D scanning during construction include various construction verifications of compliance and comparisons between planned and installed work. These include: ensuring Building Information Model scope has been installed as coordinated, verifying excavation volumes, deformation monitoring in structure and facades, plumb wall detection, collision detection, floor flatness monitoring, checks of stub-up/rebar/PT density prior to a slab pour, tracking structural settlement/deflection, and general records of construction progress for clients.
Among lasers’ many construction-related applications,3-D laser scanning is now being used for mobile mapping, surveying, scanning of buildings exteriors, documenting interiors, and archaeology. While the cost of a laser scanner may seem too high for many, it’s proven to be a good investment that ends up saving the owner money in the long run.
“We’ve found that laser scanning has a huge barrier to entry in cost, but if you own it, you find use cases for it you otherwise wouldn’t have considered,” says John Tocci, Jr., director of virtual design and construction at Gilbane.“On one project, 30 minutes of scan time in the field and30 minutes of post-processing and uploading the point cloud into a Revit model saved $30,000.”
As technology progresses, lasers are being calibrated to provide maximum power and maximum efficiency at minimum costs – all improvements that will make this new technology more affordable and mainstream.Watch movie online The Transporter Refueled (2015)
There is no doubt that the benefits afforded firms who adopt 3-D scanning in their practice will move their architect renderings into fully coordinated models. While artistic and architectural renderings are helpful in providing visualization, showing the intent of the design, and providing owner understanding, 3-D scanning offers unprecedented leaps in the way teams can coordinate, avoid conflicts, detect clashes, and gain cohesive understanding of project scope and execution. 3-D object scanning enhances the design process, speeds up data collection, reduces errors, and saves both time and money – all benefits that make it an attractive alternative to traditional data collection techniques.