Digital Terrain Model (4 cm/pixel resolution), NE distal lava flow margin, Holuhraun lava flow-field, Vatnajökull National Park, Iceland

Abstract

azu_geo_holuhraun_hot_springs: Using a Phantom 3 Pro imaging system, aerial images were acquired over short section of the NE Holuhraun lava flow margin, adjacent interior and adjacent river systems. Images were initially geocoded using the device's onboard GPS and a ground control points (GCPs) network. Final products were coregistered to more precise geocoded image data collected later in 2016. Images were processed into geodetically-controlled digital terrain models (DTMs) and orthomosaics using the commercial software package Pix4Dmapper Pro version 2.0.81. In Pix4Dmapper Pro, data products were geocoded by attributing the 3D coordinates of geocoded image coregistration targets to corresponding pixels in a subset of 2D images. The 2016 image data used for coregistration utilized DGPS measurements (See [DOI OF 2016 DATA]). To estimate the localization accuracy, we used a network of N = 7 coregistration points; the resulting mean of the root mean square error (RMSE) of x, y, and z directions (i.e., latitude, longitude, and elevation) is 2.7 cm. Both the DTM and orthomosaic products have a spatial resolution of 4 cm/pixel, but the DTM has an effective resolution of ~16 cm/pixel.

azu_geo_holuhraun_hot_springs_2016: Using the UX5-HP imaging system, aerial images were acquired over the SE and NE Holuhraun lava flow margin, adjacent interior and adjacent river systems. The images were captured in JPEG format using a Sony A7R digital camera with a 36 megapixel high-sensitivity CMOS sensor and a 35 mm focal length lens. Images were geocoded after postprocessing of the device's onboard GNSS GPS receiver and a Trimble R10 Differential Global Positioning System (DGPS) base station. The R10 DGPS is capable of producing survey points with excellent precision (0. 8 cm horizontal and 1.5 cm vertical). This allows calculation of the plane’s exact flight paths. Combined with the exact timing of the camera shutter, the positions of each image acquisition is known during the flight path and are therefore airborne control points. Images were processed into geodetically-controlled digital terrain models (DTMs) and orthomosaics using the commercial software package Trimble Business Center version 3.81. The mean standard deviations (at ±1σ) in the x, y, and z directions (i.e., latitude, longitude, and elevation) of terrain points for 2016 are estimated to be ± 3.0 cm, ± 4.0 cm, and ± 6.4 cm, respectively. The orthomosaic tiles have a spatial resolution of 1 cm/pixel; the DTM has a resolution of ~5 cm/pixel.