Technology Spotlight: LiDAR Scanning in Displacement Monitoring
Over the past couple of decades, there has been an increasing focus on the productivity gap within the global AEC (Architectural, Engineering, Construction) industry. This has prompted an influx of new systems, technologies, and companies that have touted innovative new approaches to traditional problems.
One such system is LiDAR scanning technology. In this article, we sit down with Noah Lambert, Designer, and Blaine Jansen, Senior Associate, to examine key use cases for LiDAR, discuss some of the challenges that hinder mass adoption, and offer insight into why we see such promise in the future of reality capture.
LiDAR Use Case: Construction Monitoring
Let’s examine a familiar scene for many of us urban dwellers – the construction of a new building in a congested downtown core. I spoke with Blaine about a unique opportunity to leverage innovative technology to manage construction risk in this setting.
“We are often retained to support our clients during the construction process,” Blaine says. “In some cases, that support is geared towards the construction activities themselves, whereas in other cases, it’s to support the adjacent building owners.”
The first step on these projects is to excavate the future foundation of the new building, and this is often done directly beside other buildings. The excavation contractor must install tiebacks and support systems to maintain the stability of the adjacent earth, and then rigorously monitor any deflections in that support system that might indicate ground movement.
Traditionally, this monitoring and inspection process would be performed using a total station. This is a high-precision device that locates individual points. By comparing the location of those points over time, you can assess whether the object you’re monitoring is moving. In the case of the excavation support system, you would find a handful of key points along the wall and use the total station to monitor those points over time. To evaluate deviation across time, you can picture a spreadsheet with numbers indicating the position of each point.
But with LiDAR scanning, explains Blaine, you can scan the entirety of the wall surface rather than individual spot measurements. After taking multiple scans across time, teams can then process the data using advanced software systems to provide detailed visual information showing where the subsequent scans deviate. To evaluate deviation across time, picture a heat map that shows the full wall and uses colours to identify where the wall positions have deviated.
“In this case, you can clearly see the changing behavior of the surface over time, rather than static numbers,” Blaine continues. “And this same process can be used on the monitoring scopes we undertake on pre-construction surveys of the adjacent buildings themselves.”
What Are the Benefits of LiDAR Scanning in This Scenario?
One could argue that LiDAR scanning accomplishes the same thing as using the total station – and they’d technically be right. In both scenarios, you’re monitoring the displacement of a retaining wall or adjacent building. However, the use of LiDAR scanning provides exponentially more information than the total station method.
This opens the door to more robust monitoring. In the case of the excavation support wall, you get a holistic view of the entire surface and its behaviour, rather than taking a handful of spot measurements. In the act of safety monitoring, having more information provides a competitive edge to quickly assess and address potential risks.
This approach can also yield greater efficiencies for the monitoring teams. You can take scans from up to 75m away using advanced scanning devices. This allows monitoring teams to capture a greater percentage of the wall from fewer access points, which means fewer scan setups. Effectively, LiDAR allows you to collect data faster and more efficiently relative to the traditional methods of data collection.
Looking past this immediate use case, we also see large-scale shifts in how LiDAR will enhance reality capture processes across the industry and replace typical construction and engineering workflows.
How Will This Technology Impact our Industry Moving Forward?
To understand the next steps for this technology, I spoke with Noah Lambert in Entuitive’s Restoration group to learn more about where he sees this technology moving.
Impact #1: Opening Doors to Automation
LiDAR scanning can be foundational to bringing automation into reality capture processes, especially when it comes to existing buildings. Noah explains this concept further.
“Automating the data capture of an existing building gives everyone a competitive edge because you can deliver an engineering model for existing conditions for a competitive fee. At the end of the day, the client could walk away with two 3D models – one containing the point cloud data set, and the other being the Revit model of the existing building, which the client can then use for other purposes in the future. This is really a game changer as we enter a period where existing buildings construction is becoming more critical.”
Noah also explains that the software programs supporting LiDAR scans are becoming more advanced. Some software uses the LiDAR scan data to autodetect elements in the field and automatically create those elements into a BIM model. For example, you could scan a W310x39 steel section, and the program will detect the dimensions, correctly identify that it is a W310x39 element, and then streamline the creation of the identified element into a Revit model. This is a new level of intelligence for the building industry.
Impact #2: Mobile Access to Scanning Creates More Robust Quality Control
This technology also opens the door to performing more robust quality control on projects. Consider the example of a restaurant project that Noah was recently involved with. They had their patio set in place, and the patio had to be closed down and modified during the construction period. Following construction, the restaurant owner will want to verify that they have exactly as much space as they did prior to construction. Noah describes how the team used light-duty LiDAR scanning to support this client.
“To perform this verification, I was able to use my iPad – many of which are equipped with LiDAR scanners these days – to scan the full patio before construction. Once the project is completed, I can go back and scan the patio again. From this, I can overlay the two scans and identify any discrepancies between the pre- and post-construction conditions. Through this method, our team can confirm to the owner that their patio space remained the same during the construction effort.”
It happens a lot during projects that you need to modify a structure that underlies or houses architectural elements. For example, when performing the waterproofing of a suspended slab, you need to remove the topping slab, which often has guardrails, planters, and other elements secured into it. In these cases, teams can perform a LiDAR scan before and after the project to ensure the as-built conditions meet specifications.
Impact #3: New Opportunities for Asset Management
As Noah alluded above, we’re entering an era when existing building retrofits are gaining popularity relative to fully tearing down and rebuilding assets. In this environment, asset managers will need more effective ways of identifying deficiencies in their current assets and understanding where to allocate funds.
This task of identifying high-priority remediation becomes drastically easier using LiDAR scanning. By scanning an existing building, you can obtain a digital copy of your existing assets – including the exterior façade / roof as well as interior components. The asset managers can then use that scan to see their property with a fresh perspective and see which components require urgent reparation.
Asset managers can also use these scans – or portions thereof – to prepare their scope documents to contractors and engineering firms. They can offer the engineer access to the scan for their review, and they can walk the contractor through the scope of work using the scans. This provides transparency into future work and reduces the risk of missed scopes or rework.
The Challenges to Widespread Adoption
While the LiDAR technology itself is developed, some of the supplemental technologies are hindering mass adoption of these techniques. In the final section of this article, we examine how data storage / transfer, proprietary file types, and a lack of education hinder wider adoption.
LiDAR scanning generates multiple terabytes (TB) of data. To understand that scale, recognize that one terabyte could hold approximately 500 hours of high-definition video. One terabyte is also the equivalent to the combined storage of about 16 entry-level smartphones. So, if a project scan generates 2TB of data, it becomes easy to understand why it’s difficult to store and transfer 32 smartphones worth of data in an efficient way. Noah describe his challenges on a recent project:
“We obtained LiDAR scanning services on a transit station recently, and the full scan comprised 2.5 TB of data. To address this, I needed to have a hard drive couriered to my house. This isn’t a scalable system. 4-TB Solid State Drives (SSDs) are expensive, so if you’re expected to circulate the scan to the full design team, are you copying that 2.5TB file onto multiple hard drives? This is the biggest obstacle limiting the more widespread use of LiDAR technologies.”
Another challenge is that the AEC industry has an affinity to using proprietary file types that only work with their specific software programs. Autodesk – the maker of beloved programs like Revit and AutoCAD – follows this model and has done so for years. The challenge is that this can create siloed applications that don’t speak with one another. If these programs used standard file types, then users would obtain additive benefits from using multiple software programs.
A final issue is the awareness of the full suite of programs across these workflows. When you’re watching a software vendor go through these steps, they’ve often done it hundreds of times before so they can make it look easy. But there’s still a lot of work required to get those capabilities into the hands of the field practitioners where the process efficiencies will really start to bear fruit. This applies to most new processes and tools.
Overall, LiDAR scanning technology holds immense promise to gain more granular and accurate information from existing buildings and construction projects. We look forward to seeing the industry address some of the key pain points in coming years and unlocking the true value of this reality capture technology.