The flagship project for GMAP is the Regional Geospatial Modeling project, a cooperative effort across the Gulf states with a number of universities and institutions. We began collecting data for this project in 2019, and our first flight was in Cedar Key, Florida, to support an oyster habitat restoration project by the Wildlife Ecology & Conservation program at the University of Florida.
As sea levels rise, do the elevations of oyster reefs keep pace? Healthy reefs are expected accrete to stay in a healthy intertidal range, and less healthy reefs, more vulnerable to erosion, should subside. Oysters need to spend just the right amount of time above and under water to remain healthy, and minor changes in sea level or reef elevation can make a big difference.
Before GMAP joined the effort, UF WEC was collecting elevation data with RTK GNSS surveys. We hoped to demonstrate the usefulness of UAS lidar for monitoring elevation changes over time while covering more area to gain a finer-scale understanding of the reefs’ elevation changes.
As I mentioned before, this was our first flight. We were delayed in receiving our UAS mapping system, and once we had the system in hand, we had to wait a number of weeks before we could receive training on the system and the software. We decided we couldn’t wait that long before collecting our first dataset, so we took a ride to Deer Island to make our inaugural flight.
Take a closer look at the cover image. If you are familiar with Phoenix LiDAR Systems’ SCOUT systems, you see that we put the payload on backwards. That would explain why our data came out so badly when we first tried to process it. But we made the needed adjustment to the lever arm and rotation matrix (both of which are defined in the aircraft’s body frame, so everything needed to be rotated around the airframe’s Z-axis) and we were able to salvage the flight. We weren’t sure what other mistakes we could be making, so to play it safe, we decided not to try our hand at more flights until after our training in August.
After receiving thorough instructions on how to properly attach the payload to the bottom of the drone, we set out for Cedar Key once more to map oyster habitat at Little Trout Creek and Big Trout Creek, as well as revisiting the Deer Island site to finish what we started in July.