Research on dynamic three-dimensional terrain correction methods of quantitative inversion for airborne gamma-ray spectrometer

Addressing Terrain Effects in Airborne Gamma-Ray Surveys
Led by Professor Hexi Wu and Dr. Weicheng Li, the research team achieved high-accuracy inversion of ground radioelement distributions by integrating a novel sourceless efficiency calibration method with a dynamic terrain measurement model. This combined strategy addresses two major sources of uncertainty in airborne gamma-ray surveys—spectrometer response and rapidly changing topography—both of which can introduce systematic bias in quantitative interpretation.

A Sourceless Efficiency Calibration Method Developed for Deep-Penetration Challenges
Deep-penetration effects present a critical challenge in airborne gamma-ray spectrometry, where the long-distance transport of gamma rays and varying incidence angles can lead to significant changes in detector response. To overcome this limitation, the authors developed a fast and high-precision sourceless efficiency calibration algorithm based on Geant4-based ray deposition modeling and Boolean operations. By accurately capturing intrinsic efficiency variations with incident direction, the method provides a more realistic detector response characterization, improving the reliability of quantitative inversion under complex survey geometries.

From Static Approximation to Dynamic Three-Dimensional Modeling
Unlike conventional correction approaches that apply uniform or two-dimensional adjustments, the newly proposed method dynamically constructs a three-dimensional terrain correction model along the flight path. This allows the inversion process to adapt to real-time changes in terrain height and surface geometry.The study demonstrates that incorporating dynamic terrain effects into the response matrix construction leads to more stable inversion results and reduces systematic bias. Comparative experiments show that the method outperforms traditional correction techniques, particularly in mountainous and undulating regions.

Implications for Airborne Surveys of Natural Radionuclides
Accurate mapping of natural radionuclide distributions is essential for geological mapping, mineral exploration, and environmental investigations. The improved quantitative reliability achieved by this approach supports clearer anomaly delineation and more robust interpretation of airborne gamma-ray data, especially in areas with complex topography and variable flight geometry.

Driving Progress in Airborne Gamma-Ray Measurements
The team is now working to further refine the theoretical models of airborne gamma-ray measurements and radiation field inversion methods. Future research will focus on improving the adaptability of airborne gamma-ray spectrometry under increasingly complex radiation environments.

Professor Hexi Wu noted that "This study further enhances the practical applicability of airborne gamma-ray measurements and represents a key step toward accurate quantitative analysis."

The complete study is via by DOI: https://doi.org/10.1007/s41365-026-01897-3