“Tree diameter at breast height measurement with smartphone sensors,“ (2026)

Z. Yin, S. Fei and S. Zhang, “Tree diameter at breast height measurement with smartphone sensors,“ Optics and Lasers in Engineering, 201, 109684 (2026)

Abstract:

Diameter at breast height (DBH) is a key structural parameter in forestry, widely used in forest inventory, biomass estimation, and ecological modeling. This paper presents an automated DBH measurement method using a single snapshot from an iPhone’s LiDAR and red, green, blue (RGB) sensors. The proposed method integrates automatic breast height localization from a user-tapped base point, edge-guided segmentation of the trunk, and tree diameter estimation. The method was first validated on a light pole, achieving a mean absolute error (MAE) of 1.3 cm and a root-mean-square error (RMSE) of 1.6 cm across 75 samples with different distances and viewing angles. It was further evaluated on 202 planted trees, yielding a coefficient of determination R2 of 0.966, a MAE of 1.1 cm, a RMSE of 1.5 cm, MAE percentage of 3.2%, and RMSE percentage of 4.3%, which are sufficient for tree inventory. Additionally, the method was evaluated on 287 trees in a complex natural forest environment, where it initially yielded a coefficient of determination (R2) of -0.949 due to occlusions from branches or foliage. However, after excluding the six segmentation-induced outliers, it yields a coefficient of determination R2 of 0.841, with MAE and MAE% 2.1cm and 5.7%, indicating that once the segmentation failures are excluded, the geometric measurement model remains stable and accurate even in complex natural forest settings.