Tomography is a technique increasingly used in tree inspections. This technique can be performed in two stages: field testing and postimage processing. To feed the tomographic image construction ...software, it is necessary to adopt a measurement grid composed of points positioned on the perimeter of the stem. The images are generated through spatial interpolation algorithms. From a theoretical point of view, more measurement points taken in the perimeter of the stem result in better interpolation results. However, an increase in the number of mesh points causes a substantial increase in field work and image processing time. The general objective of this study was to verify the influence of the number of measurement points of the diffraction mesh on the ultrasound tomography results. For this purpose, ten simulated discs were used, all 500 mm in diameter and with different defects in terms of size, position, and geometry. In each of the discs, diffraction grids were simulated with 6, 8, 10, 12, and 14 measurement points in the contour. The results showed that a favorable combination of accuracy and a minimization of effort can be achieved with diffraction mesh with number of measurement points calculated as five times the perimeter of the trunk in meters.
The intrinsic benefits of the urban greenery are undeniable, but the lack of planning of the urban forestry has created a great liability for its population. To guarantee environmental preservation ...with risk reduction, one must invest in research that evaluates the accuracy of technological tools that have been used in tree inspection, the results of which are used for the decision-making on urban tree management. One of these tools is ultrasonic tomography, frequently used to infer the internal condition of the stem. This research aimed to evaluate, using metrics (accuracy, precision, and sensitivity) of the confusion matrix, the quality of the image generated by tomography using conventional ultrasound equipment. For the study, disks of the species
Cenostigma pluviosum
(Sibipiruna) were used. They were analyzed considering different regions (heartwood and sapwood) and conditions (deterioration and cavities). Masks representative of these different regions and conditions of the wood were compared to tomographic images. In addition, average values of density and stiffness obtained in each region and condition were also used to validate the representation indicated in the tomographic image. Although ultrasonic tomography does not represent exactly the position and size of the internal regions of the trunk (cavities, deteriorations, heartwood, and sapwood), the accuracy (greater than 85%) and coherence with density and stiffness were sufficient to indicate its suitability as support for tree risk assessment.
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