One of the most common questions people ask us are “How accurate are maps and models generated with UAVs?” and “Are drones ready to be deployed at scale on surveying jobs?”.
To answer these questions, we partnered with McKim & Creed, one of the leading surveying companies in the United States. Christian Stallings, head of R&D at McKim & Creed and certified photogrammetrist, took an experimental and systematic approach to determining whether UAVs would be an acceptable technology to complete survey work at the firm. We had the pleasure of hosting him as a guest speaker in our latest webinar. The goals for his project were to:
1. Evaluate the performance of UAVs as it relates to accuracy and deployment cost
2. Evaluate UAV readiness for use on paid client projects
3. Determine potential prices to clients
Christian used three real-world client projects to compare the performance of UAVs with the performance of traditional surveying and LiDAR. With a scientific approach, he came to the conclusion that UAVs have similar accuracy to LiDAR (0.13 ft / 4 cm) and slightly lower accuracy when compared to traditional surveying (reaching 0.07 ft / 2 cm) (min 19:20). He also determined that the camera sensor size and lens distortion does impact absolute accuracy, as the Sony R10C camera has a 70% lower root mean square error (RMSE) compared to GoPro and DJI cameras (min 11:47, and 13:45). This means that a point identified on maps and models captured with the Sony R10C is much closer to the actual point in real world.
When analyzing cost, Christian discovered that he could reduce costs on any given project from 15%-80% compared to LiDAR (min 33:20) and 30%-75% compared to traditional survey methods (min 24:35), depending on the specifics and size of the sites. UAVs could also collect data more quickly than traditional methods and this translates into less time spent on the site by surveyors.
Christian also mentions that some of the projects would be very hard, if even not impossible, to complete with traditional methods. UAVs can survey areas that are difficult to access and often too dangerous for people on the ground. For example, on the Eagle Island project the terrain was very unstable and required the surveyors to step on plywood and move the sheets around not to sink in the dangerous mud (min 26:50).
Overall Christian found that he was able to obtain the same quality output as with traditional methods, but at a fraction of the cost and time, while also keeping people safe.
Given the new Part 107 regulations, which allows individuals to get certified as drone pilots, Christian expects more surveyors will get certified to fly legally for commercial purposes. The final goal for Christian is to have a standardized UAV in every McKim & Creed truck.
McKim & Creed also published two detailed studies comparing the performance of 3DR Site Scan with traditional methods. Here are the links to the papers of the Wrightsville Beach, NC project and Raleigh, NC landfill project.