Visibility of individual plants in UAV imagery

This dataset was used to evaluate the utility of unoccupied aerial vehicles (UAV) for monitoring tidal marsh restoration at a site in Elkhorn Slough, on the Central Coast of California, USA. To determine the size of plants visible in imagery collected by UAV, we used numbered 12" round bucket lids to mark 60 plants of two common species, <i>Salicornia pacifica</i> (pickleweed) and <i>Spergularia marina.</i> We measured the longest diameter of each individual in the field with a meter stick in order to mark 20 plants in each of three size classes (small, &lt;10 cm; medium, 10-20 cm; and large, 20-50 cm). We viewed each numbered bucket lid in UAV orthomosaics collected at 10, 30, and 60 m altitude and determined whether the plant was visible. We defined "visible" as distinguishable from the background and identifiable as a plant.