Skeye was commissioned by Deep BV from Amsterdam to carry out an aerial survey of a beach in the south west of the Netherlands. Aim of the survey was to create a digital terrain model based on aerial photography and to compare this with earlier GPS measurements as carried out by Deep. The Eagle-Eye UAS system flew 50 meters above the beach and collected around 170 images with a ground resolution (GSD) of 12mm. The area surveyed measured around 5 ha. Nine ground control points were used to geo-reference the photography. The heights were derived from the overlaps in the imagery using stereo photogrammetry. The comparison between the GPS measurements yielded stunning results. The average error measured 15mm with a standard deviation of 18mm.
The digital terrain model clearly shows that the quality of measurements from aerial photography is better than the GPS measurements due to the point density. The aerial photography yielded more than 30 points per square meter and showed all detail including tyre tracks and small tidal gullies. As a result the measurements made on the basis of such a terrain model are more accurate.