Supporting Surveyors With UAVs
Surveyors have long used both airborne photogrammetry and terrestrial LiDAR solutions to help model large or hard to access sites, but this can be prohibitively expensive for some projects. With the advent of drone-based photogrammetry, surveyors are incorporating drones into their projects to perform them faster and more frequently, at higher margins.
The three factors to consider when assessing the viability of a new and promising technology are cost, cycle time and quality. Numerous articles have identified the noteworthy savings in cost and time afforded by drone-based photogrammetry. Comparatively few studies have assessed quality. For the professional land surveyor, one of the most measures of quality is accuracy. The confidence and trust that a client has in the measurements they receive is the foundation of any good customer relationship. Drones and on-demand photogrammetry services are a relatively new service, and as such are sometimes met with skepticism from long-time industry professionals who may be unfamiliar with the technology. Understanding how accurate drone deliverables are and when they can and should be used is paramount.
Accuracy requirements vary depending on the customer and their use case, but typically our customers measure accuracy on two fronts: absolute and relative accuracy. Absolute accuracy tells you how close a point on your drone map is to the same point in the real word, while relative accuracy tells you how accurate a measurement taken between points in your model is. We strive to deliver products that are as accurate as possible on both fronts.
We’ve put together a brief study with the help of a licensed survey team to demonstrate the expected accuracy of these new technologies in an effort to build confidence in these new tools and data processing techniques. Ultimately, our results suggest that the average difference between our points and those of a professional surveyor is close enough for work done on the 1/10th of a foot scale. In general, factors that affect photogrammetric accuracy include flight altitude, the quality of the camera lens and the use of Ground Control Points.
We encourage you to download the white paper below and take a look at the results yourself. Drones are not the only solution, but for sites up to 500 acres, you can cut your field time in half, and substantially reduce costs, saving you–and your client–money, without sacrificing the accuracy of the final work product