CPD: Reality capture
Image: Lev Kropotov
As reality capture technology becomes more accessible, Lee Mullin explains how its use in an intelligent BIM environment can streamline building refurbishment.
Reality capture is the process of producing a digital 3D model representation of a building or site created by scanning it using static, mobile and aerial laser scanning and/or photogrammetry. Millions of surface points are measured and mapped to develop a textured, high-resolution, geometrically precise 3D model.
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Recent changes in hardware capabilities, portability and costs, along with improvements in the software’s ability to manage and process data, have improved access to reality capture solutions. And, as the adoption of building information modelling (BIM) has spread, the need to merge the physical site with 3D BIM content has fuelled demand for 3D capturing.
Moreover, with ever-tighter schedules, reality capture can save time and money as well as improve safety before work begins on site.
While reality capture is used in a wide range of projects, refurbishment of existing buildings is one of the most natural fits for immediate benefits. This CPD will teach the benefits of how reality capture can be used for existing buildings and refurbishment and how companies can begin to use the technology.
Current surveying practice
The current practice for capturing existing field conditions is a tedious, manual, often analog and inaccurate process that can often lead to costly rework. On a building renovation, the process looks something like this:
- Start with an image or PDF of an existing floorplan and trace it into a CAD format so that it becomes editable.
- Visit the site to verify that existing conditions on the ground match the floorplans. Measure with a distance meter or tape measure to capture any changes or inconsistencies.
- Find a way to capture complex, hard-to-measure details like exposed piping that cannot be accurately captured in a simple, efficient way.
This is a time-consuming process, and at the end of the day you may be left with sections of the site that you were not able to measure accurately, and only limited measurements available for further use.
Complex existing infrastructure can be difficult to survey by traditional methods
Older floorplans may be inaccurate and may not include changes to services and layouts. It’s therefore no surprise that projects often run into delays, design and construction rework, and costly change orders.
Problems continue as you move into design; in a 2D environment, many essential measurements can be missing, and if you’re looking to see the benefits of BIM workflows there is no easy onramp into a 3D environment.
As BIM adoption continues to grow, firms in the architecture, engineering and construction (AEC) industry not already deploying it will be impacted by increasing demand and expectation for standardised process, technological improvements and mandates.
Reality capture: the basics
Reality capture lets you create a highly accurate, full-coverage, actionable set of data that can be connected into 2D and 3D design processes. The process itself can be defined by three key steps:
- Capture: Using hardware such as a laser scanner or camera-mounted unmanned aerial vehicle (UAV), a site can be scanned capturing a detailed set of data or “points” .
- Compute: Using reality computing software tools, scan data can be automatically registered, stitched together, placed on to a co-ordinate system, cleaned up and analysed. The ultimate product is a point cloud or mesh prepared for import into CAD and BIM authoring tools.
- Create: By passing these highly accurate point clouds or mesh models into design authoring tools, designers can proceed with confidence that their base information is up to date – whether for a building renovation or large-scale infrastructure project.
Screenshots show how Revit models can be created from reality capture data
Reality capture tools, many of them cloud-connected, make data collection an interactive and collaborative process – onsite operators and project managers can measure existing site conditions, take notes, capture stakeholder feedback and more, all in real time.
Designers, engineers and site surveyors no longer need to take multiple trips to the job site to verify existing conditions. Teams can design with confidence knowing that the conditions data they are designing within is accurate, detailed and actionable.
Scan data contains complete coverage of “every point”, compared to single survey points from a manual process. Having a comprehensive scan of the entire site can help detect issues earlier than traditional methods, often giving an insight into potential problems. Once scan data is aligned to a 3D model, all stakeholders can leverage the digital model to make better decisions, such as designing an optimum layout or using materials that reduce energy costs.
Benefits during the design process
Designers gain a clear understanding of site restrictions and challenges, allowing for more creative workarounds and better preparation for handling problems at an earlier stage of the project. Reality capture jumpstarts project delivery by starting with a 3D site representation as soon as the scan begins.
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By allowing designers to design against reality rather than a model or drawing, non-perfect surfaces or other discrepancies – such as buried or hidden infrastructure – can be easily identified, preventing unnecessary revisions down the line.
Scan data can be exported into an actionable, digitised 3D model in the software of your choice – allowing designers to create models faster and adapt them throughout the project delivery as updated survey data comes through.
Current figures show that creating as-built 3D drawings in BIM reduces design schedules by as much as 40% and construction schedules by 30% – and these figures are only set to rise as adoption becomes more widespread.
Benefits during construction
Construction managers are able to make frequent, ad-hoc measurements such as a comparison analysis from the office or on site from a single, comprehensive dataset – greatly reducing labour costs. By using handheld mobile devices such as iPads, onsite operatives can view, mark up and share point cloud data from the field in real time, allowing questions, clarifications and potential clashes to be resolved as and when they arise.
Reality capture also minimises liability, schedule, risk and safety concerns by offering better construction verification through real-time monitoring and documentation.
What is driving adoption?
Significant advancements in laser scanning hardware and accompanying software technologies mean that the reality capture process is no longer reserved for specialists. Hardware and software partners have launched lightweight scanners – weighing as little as 1kg – and software packages that offer increased functionality at a fraction of the price.
These devices are so small that anyone can slip them in a backpack, go to a site, start scanning and begin processing scan data using mobile software.
Similarly, the cost of scanning a site with UAVs has dramatically reduced. Where it once took £25,000 to do a one-time scan of a site from a professional service company or LiDAR-equipped plane, you can now own a commercial drone starting at £1,000 and start flying a site on demand.
What’s more, industry professionals with no previous experience can now navigate the workflow because it is user-friendly and intuitive.
The software integrates directly with key CAD and BIM design creation tools so designers can bring reality data into the data creation tool of choice, including Autodesk AutoCAD, Autodesk Revit LT, Autodesk Navisworks, Autodesk InfraWorks. Bring these elements together, and a true scan-to-BIM workflow will get teams from push-button scan to deployable BIM model in a few hours.
Reality capture’s democratisation is leading to widespread adoption of scan-to-BIM. As the bridge between existing site conditions and an intelligent BIM environment, the reality capture process is helping designers, construction managers and surveyors worldwide deliver building renovation and retrofit projects more efficiently from start to finish.
Lee Mullin is digital construction specialist with Autodesk
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Capturing real gains in productivity
Graham Construction is leveraging reality capture technologies for competitive advantage
As the first Tier 1 contractor in Northern Ireland to achieve BIM Level 2 verification, Graham Construction is already a pioneer in leveraging cutting-edge digital tools to streamline operations within the construction industry.
The company delivers building, civil engineering and interior fit-out schemes across a diverse range of sectors, from highways and energy to education and healthcare. Its projects include the new award-winning £85m Inpatient Ward Block at the Ulster Hospital in Belfast, and the refurbishment of the Grade II listed Palace House and Stables in Newmarket, Suffolk.
Graham’s most recent BIM development has been the introduction of real-time reality capture in the field using Autodesk ReCap and Autodesk Navisworks, both part of the AEC Collection.
The firm has access to the full range of tools in the Autodesk Architecture, Engineering and Construction (AEC) Collection – all built for BIM – combined with a subscription to BIM 360. This enables it to boost operational efficiency from data capture through to client presentations.
Onsite operatives use laser scanners which create files in the ReCap app in real time, allowing them to see what they’ve scanned straightaway on an iPad. They then export this reality capture data from ReCap into Navisworks, where they can cross-reference against their models for any discrepancies.
Leveraging reality capture in this way offers a broad spectrum of benefits – from real-time onsite considerations such as uncovering hidden walls or pipes and checking that the evenness of a floor meets safety standards, to offsite considerations such as client communication and the monitoring of project progress.
Graham has already recorded a 10% productivity gain from its introduction of the Autodesk software.
This CPD has been sponsored by Autodesk