Updating of a method for measuring tree trunk diameter based on robust design

The issues of developing urbanized territories in terms of managing the city's green fund are examined. The effectiveness of green fund management depends on the reliability of measurement data on dendrometric tree parameters, including tree trunk diameter. Municipal regulatory legal acts on the establishment, maintenance, and protection of green spaces set requirements for the accuracy of tree trunk diameter measurements. Modern methods and instruments for measuring tree trunk diameter, used in monitoring and inventorying urban green spaces, are analyzed. Current methods for measuring are inefficient due to the wide variety of tree species (including unique ones) and the need to account for numerous factors affecting the growth of each tree. The advantages of using a mobile laser scanner for measuring tree trunk diameter based on its three-dimensional measurement model are discussed. The main sources of measurement error in determining tree trunk diameter in urban green spaces using the Zeb-Horizon laser scanner are described. To update the method for measuring tree trunk diameter with the Zeb-Horizon mobile laser scanner during green space inventories, robust design is proposed. An Ishikawa diagram was constructed to summarize and visually interpret the cause-and-effect relationships among error sources. Using the Ishikawa diagram, key sources influencing measurement error that need to be evaluated experimentally were identified: “Track type”, “Distance between adjacent passes”, “Convergence”, and “Rigidity”. The results of robust design were presented in the context of updating the method for measuring tree trunk diameter using the Zeb-Horizon laser scanner. Optimal conditions for geodetic survey of urban green spaces were formulated: the track type should align with “Road and trail network” or “Converging spiral”, the distance between two adjacent passes should be 4–20 m; the maximum value of the “Convergence” parameter when processing primary data using specialized software 4–5 units; the value of the “Rigidity” parameter based on information about the presence of undergrowth and shrub vegetation in the area 0–5 units. The draft of method for measuring formulates procedures for preparing and conducting tree trunk diameter measurements during green space inventory.