Urban Trees Inventory Data with Tape and iPad Pro 2020 Laser Scanner

Our objective was to test the possibility of using the laser scanner in iPad Pro 2020 to estimate trunk DBH (Diameter at the Breast Height) in an urban forest. We used 3D Scanner APP 1.9.1 (Laan Consulting Corp, 2021) installed in iPad Pro 2020, as an APP for scanning. We compared 3 different resolutions (10 mm, 15 mm, 20 mm), 2 different confidence (Low, High) as well as 2 different scanning modes (Multiple-tree mode, Single-tree mode), which combined into 12 methods for DBH estimation on urban trees (n = 101, area = 6423 m2) in Zvolen, Slovakia. The position of all trees was measured by Coordinates - GPS Formatter APP 7.1 (Mapnitude Company Limited, 2021) installed in iPad Pro 2020 at 1.3 m height. The reference data were collected by one person. It took 132 minutes with a tape. Only 3 trees were missed during the cross-section step.