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.