3D Laser Scanning for Accurate Existing Conditions

By Garrett Maldoon, Kelar Pacific

As-built drawings, if available, are only as good as the point in time of their construction. Rarely updated with intermediate modifications, you are left to estimate projects based on incomplete data. You win the bid. The only problem is the location of your pipe or duct connection is not accurate to the drawings you bid on. Now it’s time to dive into producing your own set of as-builts.

How you gather as-built details may depend on variables such as the size or complexity of a project. Tape and laser measuring still prevail as popular options. However, the new kid on the block, 3D laser scanning or LiDAR, presents meaningful benefits over the traditional methods in many cases. It is worth comparing your as-built budget with laser scanning services. Here’s why.
Considerations for 3D Laser Scanning

  • Time – LiDAR (LIght Detection And Ranging) sends out a laser beam and measures the length of time it takes for the beam to return. It is the same process your laser tape uses to measure, except laser tape is limited to capturing three points per second, whereas most laser scanners capture over 100,000 points per second.
  • Cost – How many people are sent to the job site to take measurements? One person to measure and another to take notes is common. And, for how many days? Sizable projects tend to take a several weeks or more. Laser scanning can be done by one person although a team of two people can tackle any size project in 1/10 the time of traditional methods.
  • Accuracy – When accuracy is important, there’s no substitute for 3D laser scanning. You receive down to +/- 2mm accuracy in the collected point cloud for indoor or outdoor distances of up to 330 meters. You can even read equipment labels in the photography layer.
  • Safety – You reduce the risk of injury by limiting the construction site time needed to gather information. And, laser scanning can capture details above the ceiling where accessibility is a challenge and insurance requirements increase.
  • Site Revisits – With a digital twin of the project site available on your office computer, you can eliminate additional site visits required for missed measurements. The travel time savings alone can be significant.
  • Phase Progress Reports – A point cloud and picture are worth more than 1,000 words. Laser scans can easily track project changes, deviations, and critical progress points to backup regular phase reporting.

The Point Cloud

The laser scan produces a complete picture of the existing conditions known as the point cloud. Pictures can accompany the point cloud to provide additional context. Let’s look at three ways you can harness the point cloud information.

  1. Measurements –

Imagine doing site verification from the comfort of your office. Most laser scanners enable you to view the point cloud and associated pictures using a Web browser. Now any project stake holder can take exact measurements and exchange ideas in the real context of the project site.

  1. Background –

View the point cloud as a CAD or BIM background in place of architectural drawings. The point cloud enables you to design your detailed shop drawings with accurate context of the space. Not only is the point cloud a better method, but it also provides realistic information compared to measurements alone.

3. Convert the Point Cloud into Geometry –
The point cloud delivers enough data to create a complete model, if necessary. Your designer or detailer can interpret the point cloud as they create the CAD drawings or BIM model. If you work with piping, AI software exists that can identify cylinders and planes to help with the task. Creating models with a point cloud delivers accurate as-builts thus eliminating field issues experienced on renovation projects.

Outsource 3D Laser Scanning

The next bid you win presenting a monumental as-built effort is the perfect project for 3D laser scanning. Start with an AEC services firm who can deliver the collective point cloud if you prefer to create the CAD / BIM models yourself. Otherwise, look for a firm that can deliver both the point cloud and the model according to your required Level of Detail (LOD). You might even find “scanning to BIM” is the solution for participating in BIM required projects when you don’t have a BIM team.

With 3D laser scanning, you can greatly reduce those shrugs of uncertainty and interrupted sleep wondering when the next major issue will appear. Working with the real existing conditions from the start contributes to successful project delivery throughout the construction phase.

 

Garrett Maldoon is an AEC Specialist and Revit Certified Professional at Kelar Pacific, LLC. Kelar Pacific provides technology services, software, and training for the architecture, engineering, and construction (AEC) industry. Specialties include 3D laser scanning, drone photogrammetry, robotic station point layout, BIM modeling and coordination and 4D pursuit videos. Kelar Pacific is a Gold Partner for Autodesk and Bluebeam products. Additional products and consulting include Primavera, Sage, Procore, BIMTrackStrucsoft, and Fuzor (VR). For more information visit www.kelarpacific.com or call 800-578-2457.

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