STUDY ON CREATING CROSS SECTION OF THE OLD GIANT OLD TREE’S TRUNK FOR ACQUISITION OF SONIC TOMOGRAPHY

Abstract. This study aimed to improve the usefulness of 3D scanning as an alternative to the biased measurement method for getting tree trunk geometry using a calliper in sonic tomography for tree health diagnosis. To this end, this study constructed geometry information using PiCUS Calliper and a 3D scanner on an old giant tree located in Buyeo-gun and compared the results with sonic measurements.

Of the two instruments, the 3D scanner has the advantage of realizing the geometry of the object more closely than the calliper, which uses the principle of three-point surveying. Provided that Section A produced through the 3D scanning is more similar to the actual geometry, and the error range of the data acquired by the 3D scanner is within 1–3cm, the deviation of −0.2 to +0.9% in the perimeter of the two geometries is insignificant, and the section based on 3D scanning is more similar to the actual tree trunk than the calliper. However, while the calliper-based section was not significantly different from the 3D scanning-based section geometry, the problem of exaggeration and distortion in the bumpy parts of the tree was identified. This confirms that 3D scan data can be used as a tool to accurately realize the section geometry of the tree trunk. On the other hand, the sonic tomography results obtained based on the two geometries also showed a difference in the total area and the area where the symptom appeared. However, to accurately calculate the extent of the symptom, a quantitative comparative analysis of the actual sonic velocity value in addition to the area is required, which is a limitation that was not covered in this study.