Along a small slice of the Norwegian coastline southeast of Oslo, two members of the SeaBee team ventured out in the bitter cold to test equipment and kick off the first SeaBee survey of 2021. The drone test flight was planned to capture high-resolution RGB images with a clarity of 1×1 centimetres, gather multispectral data, conduct thermal imaging, and assess high-accuracy and precision-position data. This test marked a milestone for the project, as it was the first time that the versatile flight planning software “UgCS” was tried out and used in the field.
Join an animation “tour” of a 3D model of the beach zone and its surroundings, created by stitching together numerous RGB pictures from the first test flight using the PIX4D software package:
Medyan Ghareeb Antonsen, Senior Engineer at the Norwegian Institute for Water Research (NIVA), and Yalei Li, a PhD student from China, chose Danmarkbukta, in the outer Oslofjord, because it’s a spot where seaweed deposits tend to accumulate.
“Yalei’s project aims to quantify deposits of macroalgae and seagrass in the beach zone using 3D modelling gathered from high-resolution RGB images,” said Antonsen. “So we managed to hit ‘two birds with one drone’ in the field.”
Photo: Beach deposition of various macroalgae species and eelgrass washed up on a beach after a storm. Oslofjorden, exposed beach outside Larvik. Kasper Hancke, NIVA, September 2017.
Photo: Yalei Li setting up for fieldwork at Danmarkbukta. Medyan Antonsen, NIVA 2021.
The UgCS software is a more versatile and less consumer-focused drone flight planner than the built-in DJI route planner. Though Antonsen and Li faced some minor issues with connections and communication in the field, they were well-prepared after dealing with several problems in the lab before the test flight.
“Sometimes the worst thing that can happen is when things go smoothly in the lab,” commented Antonsen.
For the RGB regular photos, they used a SONY RX1RM2 42MP camera with a global shutter, providing very high-quality photographs. This camera operates with a fast mechanical shutter to reduce rolling shutter distortion, similar to a “super compact” single-lens reflex camera. To capture the thermal images, they attached a MicaSense Altum 5band Multispectral camera with thermal capabilities to the drone.
“The MicaSense is a very compact multispectral camera with a good resolution and thermal ability,” noted Antonsen. “We have had a lot of interest in the thermal capabilities for groundwater studies and wanted to test it out, so this proved to be an excellent opportunity.”
Danmarkbukta images captured in 2D, RGB Blue light, and Infra-Red spectrum. Medyan Antonsen, NIVA 2021.
To ensure accurate mapping of the area, they also used a Reach RS2 GnSS base station, enabling for around 3-to-5-centimetre absolute positioning accuracy between ground control points and the base station.
“We learned that our equipment performs as expected, the picture quality from the SONY RX1RM2 is just as good as what we have seen before, and the MicaSense Altum also performed well,” Antonsen remarked. “The UgCS flight planning software is versatile as expected. However, due to the cold, it was good to have the built-in DJI pilot software for when the laptop decides it’s too cold to do anything!”
That day the temperature was not unusual for winter conditions in Norway, but surely an inherent challenge for sophisticated electronics.
Photo: Medyan Antonsen piloting a SeaBee drone for the first test flight of the year at Danmarkbukta. Yalei Li, 2021.
The cold proved to be the greatest challenge during this test run, as batteries will not allow the drone to take-off at temperatures lower than minus 15C. It also provided a valuable learning experience, indicating that the next field campaign at similar temperatures will need to include more heat packs and hot water thermoses.
“I think a big flask of hot chocolate will be the most effective addition next time!” joked Antonsen.
Photo: Medyan Antonsen battles freezing temperatures at minus 15C during the first test flight of the year for the SeaBee project in Danmarkbukta. Yalei Li, 2021.
The team is now playing a waiting game as it plans the next steps for this part of the project, which will use drone images to map and quantify beach depositions of seaweed and seagrass. The researchers are waiting for the snow to melt and a storm to come by, as this will lead to build up of beach deposits of marine vegetation and debris, and facilitate for the method development part of the project. The next time weather allows, the team will also send drones over its areas of interest twice, on overlapping routes, as it discovered that this is necessary for good quality thermal imaging, especially when detecting small differences in temperature on the ground and in water.
Antonsen and Li are looking forward to their next round of fieldwork, and not just because it will (hopefully) be warmer.