Integrated photogrammetry and photoclinometry for enhanced 3D surface reconstruction of asteroids

¹ Research Centre for Deep Space Explorations | Department of Land Surveying & Geo-Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
² Beijing Institute of Spacecraft System Engineering, China Academy of Space Technology, Beijing, China

^★ Corresponding authors: This email address is being protected from spambots. You need JavaScript enabled to view it. ; This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 4 October 2025
Accepted: 17 February 2026

Abstract

Stereo photogrammetry (SPG) and stereo photoclinometry (SPC) are the main techniques used in the 3D surface reconstruction of asteroids. The SPG approach retrieves accurate 3D geometry with limited spatial resolution, while SPC extracts fine-scale topography from image intensity but suffers from uncertainties in albedo and other factors. Integrating SPG and SPC therefore mitigates the limitations of each method when used alone. However, surface occlusions, illumination variations, and insufficient spatial coverage in asteroid observations pose challenges to integrated SPG–SPC. This paper presents an integrated photogrammetry and photoclinometry approach that leverages a pixel-weighted maplet (PWM) strategy specifically designed to address these challenges to obtain enhanced detailed 3D surface reconstruction of asteroids. The approach comprises four key steps: (1) reconstructing a sparse-resolution asteroid surface model using SPG, (2) generating PWMs by incorporating GPU-accelerated occlusion detection and an embedded optimal weighting strategy for image pixels to enable enhanced SPC refinement, (3) iteratively refining the surface of PWMs using SPC, and (4) assembling high-resolution PWMs into a complete global 3D model of the asteroid. We tested the developed method for 3D surface reconstruction of asteroids using actual images of the asteroid Bennu and images of a 3D-printed model of Bennu in a test field with controlled illumination and imaging settings. The results demonstrate that the proposed method achieves superior geometric accuracy and captures finer topographic details compared with state-of-the-art approaches. This development represents a notable advancement in high-fidelity asteroid modeling, offering critical support for future asteroid exploration missions and scientific research.