“Extending Smartphone LiDAR Range for True-Scale Tree Trunk Height Estimation,” (2026)

W. Xiang, S. Fei, and S. Zhang, “Extending Smartphone LiDAR Range for True-Scale Tree Trunk Height Estimation,” Optics and Lasers in Engineering, 205, 109877, (2026)

Abstract

This paper presents a novel method to extend the effective measurement range of the light detection and ranging (LiDAR) sensor embedded in the iPhone Pro for tree trunk height estimation since a smartphone can be used to measure objects with image-based methods but lack inherent true scale, while LiDAR-based approaches suffer from a short operating range. The proposed approach scans the trunk, adaptively selects key frames, reconstructs unscaled 3D point clouds using a Structure from Motion (SfM) framework with hierarchical reconstruction merging, computes the true scale using LiDAR data within its reliable sensing range, and generates a 2D panorama. Tree height is then estimated by calculating the distance between two user-selected points on the 2D panorama using a ray-casting method. The proposed approach was evaluated on 248 trees in forestry environments. For all evaluated trees, at least part of the stem exceeded the effective sensing range of the smartphone LiDAR sensor (approximately 0.2-5 m). Across all target-height measurements, the method achieved a mean error of ft and an RMSE of 0.72 ft for tree trunks up to 40 ft in height. These results demonstrate that the proposed method provides sufficient accuracy for forestry applications.