Via Sensfly. An Arkansas farm operator sought to test Sensefly UAV survey accuracy to see if data were usable for planning and levee design compared to ground-based RTK surveys. The ground RTK surveys are typically performed by having the RTK unit mounted on a vehicle and driving the site. The terrestrial RTK method is often problematic, since fields may not be readily accessible due to mud from frequent Arkansas rains. After testing, the operator stated, “there’s enough correlation between the two methods to conclude that the eBee Plus, with its RTK/PPK function, provides a viable source of data for elevation surveys to be used for levee line placement and earthwork designs. There were negligible differences between the two survey methods.” (My emphasis.)
We at PLS obtain similar accuracy. Negligible differences. After “ground truthing” data from our projects, our confidence in UAV based topographic surveys only grows. But the conditions must be right. That is, trees and vegetation must be removed from the site, and/or the ground closely cropped by mowing or bush hogging to obtain the desired accuracy. In cases where trees or other vegetation are present on portions of the site, we supplement UAV data with ground-based survey methods. The photo above shows a side-by-side comparison of UAV RTK and ground-based RTK survey methods.