Remote sensing coastal recovery using drones

Over the last summer our drone survey team was busy optimising methods for measuring change in the coastal environment change. We now have a comprehensive set of 3D models and imagery from 30+ field sites. Advantages of drone technologies include the ability to cover more ground and a greater range of habitats than we can manage in ground-based surveys alone, yet the resolution of these methods is impressive. Each model covers several hundred metres of coast and the size of each pixel is < 1 cm on the ground! We are using the drone data to assess intertidal area changes which are potentially some of the most important and long-lasting earthquake impacts e.g. where the area of characteristic zones has been reduced from their pre-quake size. Within these areas we are using photogrammetric methods to follow seaweed recovery, building on earlier trials of options for this type of analysis (see Recover issue 3).

Two views of a remote-sensed scene near Waipapa Bay. (a) ortho-rectified image with a pixel size of 0.7 cm. (b) digital elevation model produced from the same dataset. Note that the usable data can include shallow submerged areas (if the water is clear!). Picture by Shane Orchard.

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