Motion Sensitivity Analysis and Terrain Correction for UAV‐Borne Gamma‐Ray Spectrometry

ABSTRACT Uncrewed aerial vehicles (UAVs) equipped with gamma‐ray spectrometry sensors enable high‐resolution surveys but face challenges in rugged terrain. Conventional airborne gamma‐ray processing commonly approximates the source–detector geometry using a single height‐above‐ground parameter. This approximation is often unsuitable for low‐altitude UAV surveys, where rapid topographic changes, variable flight altitude, and platform motion can influence the measured response. This study first evaluates platform motion using a moving point‐spread function sensitivity analysis to quantify footprint elongation associated with survey speed, integration time, and flight altitude. A three‐dimensional, grid‐based terrain‐response model is then developed to account for variations in source–detector distance, terrain geometry, and line‐of‐sight visibility. Controlled synthetic simulations are used to evaluate the model under known terrain and source configurations. The motion analysis shows that footprint elongation is small under typical survey conditions but increases with higher survey speed, longer integration time, and lower flight altitude. The synthetic simulations further show how terrain geometry changes the measured response and demonstrate that the terrain‐response model recovers the known source distribution. When applied to UAV radiometric data collected over a rugged porphyry copper–molybdenum deposit in Arizona, USA, terrain‐correction magnitudes reached approximately 15% in areas of pronounced topographic relief. The largest adjustments occurred on slopes, ridges, and in topographic depressions, indicating that terrain effects were the primary source of geometric variation under the conditions examined. The proposed workflow provides a practical approach for identifying and correcting geometric effects in low‐altitude UAV gamma‐ray surveys over complex terrain.