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Deliver a new era with 3D point clouds

Dillon Fugate | 23 May 2017 | Comments

There is an iconic scene in the 2002 film “Minority Report” in which Tom Cruise’s police detective protagonist furiously maneuvers content around a wall-sized computer screen by waving his hands. The more images he can view, the more accurate and complete a picture he can build.

The scene encapsulates a similar challenge that we, as designers, come across every day. To accurately model a project site, we need to safely and efficiently collect millions of data points which document a site’s every nook and cranny. The more detailed the data we collect, the more accurate and complete our models will be. The less detail we use, the greater risk of problems arising later-on. Using 3D point clouds to model projects is a popular way to reduce time spent in the field while producing more accurate images.

There are multiple ways to collect high definition surveying (HDS) or 3D point cloud data in the field. Laser Imaging, Detection, and Ranging (LiDAR) uses a pulsed laser to emit a beam and gathers large amount of data points by using the known speed of light and the amount to time for the signal to return. Phase-based scanners emit a constant laser beam into multiple phases and compares the shifts in the returned laser energy. Photogrammetry-based point cloud data utilizes digital photography processed through select software packages to create 3D point cloud data. Each of these technologies have advantages and limitations.

LiDAR data collection is not as fast as the phase-based and photogrammetry, but has better range and is generally more accurate than photogrammetry. Phase-based HDS is quicker than LiDAR and can collect very dense and accurate close range data sets. Photogrammetry-based HDS is more affordable than the other approaches, and due to being lighter in weight, can be more easily utilized with aerial and ground-based equipment.

While these methods have been standard practice in surveying for some time, new technologies are currently being introduced which greatly improve data accuracy, lower costs, and reduce health and safety risks. Unmanned aerial vehicles (UAVs), or drones, are quickly ushering in a new era for surveyors. Cheaper and more versatile than manned aircraft, UAVs can be fitted with off-the-shelf digital cameras that are used to produce overlapping or “stereo images” of a project site. The stereo imagery is then used to produce key outputs for a 3D point cloud.

The benefits of capturing quality data to develop 3D point clouds cannot be overstated. To create an accurate model of a project, such as a building or bridge, thousands of precise measurements need to be made. In the old days, these measurements were collected by hand, a time-consuming and sometimes dangerous process that lacked the accuracy and detail required by today’s architects and planners. Now it is as simple as pointing a 3D laser scanner at a target, which can collect millions of closely spaced measurements in a matter of minutes.

At Atkins, we have been using these tools to safely collect and model accurate as-built data for dozens of projects across the country. The newly constructed Davis Barracks at the historic U.S. Military Academy in West Point, New York, is an example of how we utilized HDS to capture detailed 3D data. The barracks sit at the base of a cliff overlooking the Hudson River, so any attempt to survey the facility using conventional methods would involve repelling down the cliffside to capture accurate measurements. This is obviously a dangerous and inefficient way to do our jobs. Using HDS to capture the necessary datasets, then uploading them into a point cloud to create accurate, 3D models helped reduce our field time while keeping our people safe.

On the UAV front, we have been utilizing UAVs for a wide variety of survey projects, including helping the State of Alabama survey bridges and other structures crossing the Tennessee River. The data will assist the State and the Federal Emergency Management Agency (FEMA) update FEMA’s RiskMAP program that assesses flood risk. We have also been using drone-based technology for construction planning, most recently by coordinating the first commercial drone operation at a major U.S. airport earlier this year.

In the future, as costs go down and demand for mobility increases, the ability to develop a hybrid of ground- and aerial-based technology will present opportunities for even more accurate and efficient data collection. The faster surveyors and designers adapt to these advancements, the better positioned they will be to model and design the projects of the future.