Low-cost mobile laser scanning for urban tree assessment: accuracy evaluation and application potential

Recent advances in mobile laser scanning (MLS) have enabled rapid three-dimensional data acquisition for urban tree monitoring, providing an alternative to traditional terrestrial laser scanning (TLS) and photogrammetric approaches. However, the high cost of commercial handheld mobile laser scanning (HMLS) systems limits their routine use in urban green-space inventories. This study evaluates the performance of a low-cost wearable MLS prototype based on a Livox MID-360 sensor and compares it with two commercial HMLS systems (Stonex X120GO and Stonex X200GO) for urban tree assessment. The analysis was conducted in an urban park environment and included 80 individual trees. Tree detection rate (TDR), diameter at breast height (DBH), tree height (TH), crown projection, and point cloud quality were evaluated using commonly applied processing workflows (RayCloud with ITSMe, FSCT, and 3DFin). Using the best-performing workflow, the prototype achieved a DBH RMSE of 2.47 cm and a TH RMSE of 0.43 m, compared to 1.25–2.08 cm (DBH RMSE) and 0.31–0.40 m (TH RMSE) for the commercial systems. Mean cross-section quality metrics further supported data reliability, with Cross Section Quality Index (CSQI) values of 0.78 for the prototype and up to 0.83 for the high-end system, and corresponding Standard Deviation of Radial Distances (SDRD) values of 0.034 m and 0.018 m, respectively. Despite lower point density and increased noise, the low-cost wearable MLS prototype provided comparable TDR, DBH, and TH estimates. Differences in processing time were mainly driven by the selected workflow rather than by the scanning device. Overall, the results demonstrate that low-cost wearable MLS systems can deliver reliable urban tree metrics when combined with suitable processing methods, offering a cost-effective alternative for urban tree inventories and operational monitoring.