Fig. 7
Process of measuring trunk diameters directly from point clouds via the χ2-filtering method. (a) Changes in the PDF curve of the 2-distribution during the iteration process. Specifically, the red point marks the location of the maximum probability density on this curve. The corresponding x-coordinate (9.11) signifies the radius of the tree trunk. (b) Distribution of rejected and retained point clouds on the trunk’s cross-section during iterations. The notation I- 1–1–5 refers to the point clouds rejected during iterations 1 through 5, while I- 0 represents the retained point clouds. Additionally, the red circle depicts the circle drawn using the radius of the trunk, and the blue one is the circle drawn using the field-measured diameter