How to Leverage Drone-Generated Point Clouds in BIM Software

High-resolution site models assist with planning, quality control, and more for design and construction.

Drone mapping adds value to all phases of a construction project, including initial site survey and design, volume and elevation measurements and comparisons, and quality assurance, as virtual design and construction teams are quickly learning. A drone can automatically fly over a project site and collect pictures that can be turned into highly accurate point clouds compatible with Building Information Modeling (BIM) software in a fraction of the time it takes to do a ground-based survey.

Setting the bar for drone mapping in construction is the VDC team at Brasfield & Gorrie, one of the biggest privately held construction companies in the United States. Each of the regional offices of Brasfield & Gorrie is outfitted with DJI Inspire series drones, and the 24-person VDC team has integrated drone mapping into regular business operations.

Models for Surveys produced in a shorter amount of time

A 60-acre plot may easily take two or even three weeks to survey using conventional ground methods. Drone mapping shortens the time it takes for Brasfield & Gorrie's VDC team to load the point cloud into BIM software from the time of the initial request to four days or less. The data collection process is where some of the biggest time savings are made. Flying and collecting mapping imagery often takes less than an hour for construction sites. Then, without burdening your own servers, just submit the flight images to the cloud-based DroneDeploy platform and wait for them to be converted into a map and 3D model.

Project managers also don't have to give up accuracy. Customers using DroneDeploy are able to attain centimeter-level accuracy by using ground control points (GCPs). DroneDeploy enables VDC teams to export point clouds into regional coordinate systems after the 3D model is complete by by supplying a 4-digit EPSG code. In comparison to conventional ground survey methods, the outcome is survey-grade data in a far shorter amount of time.

"We watched as a 2-3 week process that cost several tens of thousands of dollars to complete was reduced to a 1-4 day process with only a few thousand dollars invested in hardware and software," adds Cole. "It's incredibly powerful when you're looking at a huge 75% or larger cost and time improvement."

The Work of VDC Teams Is Revolutionized by High-Resolution 3D Models

Drone-based surveys are not only more quickly carried out than ground-based surveys, but they also provide far more detailed data. A typical survey might only produce a few hundred resolution points, whereas point clouds created by drones can have millions of points. The outcome is a high-resolution 3D model that has completely changed how VDC teams and the project and site managers they collaborate with do their work. When Cole examined a 3D model of one of Brasfield & Gorrie's locations, he realised how extensive this was.

Large-scale point cloud

He could see every electricity wire over the construction site and every individual stud in the multifamily housing complex that was being built thanks to the 3D point cloud's extreme detail. In fact, when he recently exhibited one of the point clouds his team creates to a colleague, it was mistaken for a film due to how precise it was.

"I said no, no, this is truly a 3D modeling services, and I can obtain the amount of any material stockpile on that site, I can make any linear measurement—so this is a pretty detailed point cloud that illustrates the level of data you can acquire," the person responding stated. [Hunter Cole]

BIM Integration of Drone Point Clouds Enables Effective Analysis

The process doesn't end with a finished point cloud produced by a drone. Once the model is incorporated into BIM software, the actual power emerges. The Brasfield & Gorrie team creates point clouds in DroneDeploy, imports data into Autodesk Revit, and then superimposes it with 3D site plan models and other data to enhance processes including initial site survey and design and quality assurance by comparing actual construction to plans

• Tracking and evaluating alterations over time

The DroneDeploy interface's Autodesk app makes it simple to send point clouds right to your Autodesk Forge account.

Here are a few instances of how Brasfield & Gorrie uses point cloud information from BIM software to inform its judgements.

Planning the site

In order to confirm and optimise where to position the cranes during the construction process for this tower, the VDC team superimposed the architect's design for the project as well as crane clearances onto a 3D point cloud of the existing site.

Combined point cloud fly-through, design monitoring earthwork

Heat map comparing the site plans to the earthwork. Green indicates that elevations follow design plans; blue, too-low altitudes; and red, too-high elevations

The Brasfield & Gorrie team used a drone-generated 3D point cloud to enable a site manager verify a subcontractor's early earthwork with site plans while building a 61-acre hospital site in Florida.

Accuracy and promptness were essential since the site management was worried that the subcontractor had not exported enough soil.

The site manager was able to draw the conclusion that the subcontractor did need to export more soils to reach the proper altitudes from the heat map that represented the external contractor's earthwork progress in comparison to the original plans.

Concrete and pipe work verification

VDC teams can even superimpose current design models atop point clouds created by drones that show the site's conditions.

In this case, Brasfield & Gorrie used a 3D model of the site conditions to overlay the design model for this processing plant on top of it to ensure that concrete footings and pipelines were installed correctly.

Hunter Cole, the VDC Coordinator, explains, "I can overlay a point cloud over that 3D model, line it up precisely, and see, for the first time, what's been created versus the original purpose."

Where to Find Out More

Watch our webinar, A Drone on Every Job Site, to learn more about how virtual design and construction teams are utilising point clouds produced by drones.

Check out the following links in our support area for more information on supported export formats and how to transfer data from drones into BIM software:

Guidelines for creating 3D models

Supported export formats

How to examine and export point cloud data

Start using DroneDeploy to map

Do you want to know how Drone Deploy can benefit your company? Visit begin your free trial or schedule a meeting with a member of our team, go to www.dronedeploy.com. For both iOS and Android smartphones, a free download of the Drone Deploy mobile app is available.