The altitude hold mode was used to fly at approximately 50m above ground level (AGL). A live radio link allowed visualisation of real-time position information on a map, which helped the UAV pilot to follow over- lapping flight paths that covered the study area. Each 18 megapixel photograph covered approximately 64 m by 43 m on the ground at 1 cm resolution. Around 200 photographs were captured for the site covering the core area of the moss beds, however, the ridge was too large to cover the whole watershed. The photographs were visu- ally assessed on the basis of quality, viewing angle, and overlap, in order to remove blurred and under- or over-exposed images from further processing and analyses. For more detail on the UAV setup also see Turner et al. (2012).