Geo-referenced orthophotos of the Tanana River, Alaska, acquired July 24, 2019

This data release consists of an orthophoto of the Tanana River in Alaska acquired on July 24, 2019. The orthophoto was produced from images obtained using a Hasselblad A6D-100C 100 megapixel digital mapping camera deployed within a pod mounted on the landing gear of a Robinson R44 helicopter. Images were acquired as the helicopter transited a series of flight lines designed to provide complete coverage, with ample overlap, of the study area along the Tanana River. Also within the pod was an ATLANS GPS/Inertial Motion Unit (IMU) that recorded the position and orientation of the platform during the flight. This information was used to geo-reference the images by performing aerial triangulation and bundle adjustment within the TerraSolid software suite, which was also used to produce a LiDAR DEM that was incorporated into the orthophoto production process. The resulting orthorectified image had a spatial resolution (pixel size) of 0.1 m. The image is saved as a GeoTIFF file with an embedded header that contains the spatial referencing information for the image; the projected coordinate system is UTM Zone 6N, NAD83. The main purpose of this orthophoto was to serve as a base for geo-referencing the video described in a related data release accessible from the parent landing page cited above.