The QUAKES‐I Stereoimaging Instrument for Measuring Surface Topography and Land Surface Processes

Abstract QUAKES‐I is a stereoimaging instrument for recovering surface topography to study land surface properties and processes. The instrument consists of an 8‐camera array with four cameras pointing forward and four pointing aft. Overlapped imaging during a flight‐line enables reconstruction of topography. The instrument has flown on a NASA Gulfstream V aircraft at 12.5 km (41K feet) above sea level and can cover 5,400 km (3,400 mi) linear distance in a 6‐hr flight. For this altitude, the image swath is 12 km wide with a separation of 5 km between the forward and aft swath (22°). The instrument is accommodated on a King Air aircraft for flying at lower elevation providing higher resolution data. We focused our engineering test flights over the Grand Canyon, Lake Mead, and a variety of terrain including coasts, faults, forests, lakes, desert, and steep mountains. Data products for the 12 km wide swaths are 15–30 km long with sub‐meter ground sample distance. We describe here the instrument and projected accuracy. We used commercial Structure from Motion software packages Pix4D, Metashape, and RealityCapture to process QUAKES‐I data. The accuracy of QUAKES‐I data products is typically <2 m for trees and steep terrain. This paper focuses on the instrument implementation.