D800 camera

The image acquisition system was composed of a DJI rotocopter Matrice 600 UAV (DJI, Shenzhen, China) and a Nikon D800 camera (Nikon, Japan) in this study. The UAV could hover for 35 min without a payload. In this study, each mission took about 13 min with a payload of 2 kg. A GPS module was integrated into the UAV, which was tested with a horizontal accuracy of 0.5 m and a vertical accuracy of 1.5 m. The Nikon D800 camera fitted with a Nikon 50.0 mm f/1.4D lens was mounted on the UAV to collect nadir RGB images of the rapeseed field during flights. The complementary metal oxide semiconductor (CMOS) sensor of the camera had a size of 35.9 mm × 24.0 mm, capturing images with 7,360 × 4,912 pixels. The camera was also integrated with a GPS device to geotag the images and a wireless control to trigger the camera capturing imagery every 1.0 s automatically. An SD memory card was used to store JPEG images with a 24-bit format.
Each flight mission followed the same camera configuration during the whole rapeseed leaf growth stage. The frontal and side overlaps of the flight path were 80.0 and 70.0%, respectively. Two perpendicular flight paths were conducted to cover and image the rapeseed canopy. In this study, the UAV was flown at a ground speed of 3 m/s and at a height of approximately 30 m above ground level, and spatial resolution of image was about 0.18 cm.

Cells were grown in LB from a single colony isolated over LB plates to a mid-logarithmic phase (4 h at 37°C with shaking). For floating biofilm assays, the inoculum ratio was 1:1,000. Pellicle phenotypes in cultures grown at 23°C were observed. Photos of floating biofilms were acquired with a NikonD800 camera (Nikon, Tokyo, Japan) or a stereomicroscope (Zeiss, Oberkochenm, Germany) and images were optimized for contrast and brightness, with adjustments kept consistent. For evaluation of the effect of the surface area on pellicle formation, cells were re-diluted 1:1,000 in liquid MSgg medium in cell-culture multiwell plates (Thermo Scientific, Waltham, Massachusetts, USA) of 48, 24, 12, or 6 wells, containing a total volume of 0.85, 1.58, 2.95, or 8.6 ml of medium per-well, respectively, in order to reach comparable height without shaking. Plates were incubated at room temperature.