###### Abstract  
A field-integrated methodology using 3D ultrasonic tomography supported by close range photogrammetry (CRP) has been developed and evaluated as a tool to detect the presence and patterns of decay forms in a living adult holm oak (_Quercus_ _lix_ L.) in an urban green area of the city of Cagliari, Sardinia, Italy. Close range photogrammetry was used to compute a high resolution 3D model of the studied tree, texturized with natural colors. Moreover, following the implemented workflow process it was possible to evaluate the deformation pattern of the studied tree over time. In a second step of our integrated approach, and in order to diagnose the state of health of the inner part of the studied tree in a non-invasive way, laboratory and in situ non-invasive ultrasonic techniques were applied. The results of the close range photogrammetry analysis supported the optimal design of the 3D ultrasonic tomography of the living adult holm oak. Ultrasonic tomography is one of the most powerful non-destructive testing techniques for the full-volume inspection of a structure. It produced physical information on the inner structure of the stem of the investigated tree. The results of the study show that the integrated application of close range photogrammetry and 3D ultrasonic tomography is a powerful tool for a highly accurate and objective evaluation of the external and internal decay of trees and for monitoring their conservation states. With the fully integrated approach, the diagnostic process aimed to prevent instability and the failure of trees can be greatly improved. wood decay; close range photogrammetry; 3D ultrasonic tomography; risk failure; holm oak +
Footnote †: journal: Applied Sciences  
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Footnote 1: email: {[PERSON], [PERSON]; [PERSON], [PERSON]; F.  
close range photogrammetry (CRP), considerably less expensive. Since the latter is one of the most precise surface data methods in use, it is becoming very popular for the 3D modelling of trees [3; 4; 6]. Moreover, among the techniques available for the modelling of the trees in forests or urban areas, internal body techniques are very effective in detecting physical parameters relating to the state of health of the inner parts of the trees or the quality of the wood. All these internal body methods of investigation are non-invasive and are part of so-called non-destructive testing (NDT). Tests in this category include near-infrared (NIR) spectroscopy, an effective laboratory technique for measuring the physical, chemical and mechanical properties of wood, and acoustic methods, which are suitable for both laboratory and in-field tests [7; 8; 9; 10; 11]. Acoustic methods are based mainly on the measurements of the acoustic velocity relating to the elastic and mechanical wood properties. The use of elastic waves propagation to detect wood decay in trees has been analyzed by many researchers [12; 13; 14; 15]. The detection of the low elastic characteristics of the wood due to its decay is based on the observation that wave propagation is very sensitive to the presence of decay, often caused by fungal decomposition, because it worsens the elastic-mechanical properties of the wood [16]. For accurate acoustic analyses, 3D low frequency ultrasonic tomography, which was developed for medical application and geophysical prospecting, was found to be especially effective for its applicability both in laboratory and in standing trees [14; 15; 17]. The possibility of integration of different non-invasive diagnostic methods for the analysis of the surface and inner parts of a tree is interesting and topical. For instance, CRP can provide 3D high resolution measurable models useful in the application of 3D ultrasonic tomography. The integration of geomatic and acoustic techniques is adopted in many fields of the applied sciences [6; 18; 19; 20; 21; 22]. The CRP technique is based on the well-known structure from motion (SfM) photogrammetry method and is performed essentially with the application of computer vision and computer graphic algorithms.