The PiCUS Sonic Tomograph is used for tree risk assessments in order to measure the thickness of the residual wall of trees with internal defects such as cavities or decay non-invasively. Most often the PiCUS sonic tomograms are recorded near ground level of trees. However, acoustic tomograms also reveal important safety information about the breaking risk near branch wounds and above ground cavities.
Operational theory of the PiCUS Sonic Tomograph
The PiCUS Tomograph measures the velocity of sound waves in wood in order to detect decay and cavities in standing trees non-invasively. The acoustic velocity depends on the modulus of elasticity and the density of the wood itself. Most damage and disease causes fractures, cavities, or rot and reduces the wood’s elasticity and density. The sketch displays the basic working principle, in that sound waves cannot take a direct path through the wood (red dotted line) if there is a cavity between the transmitter and receiver.
The acoustic waves are created manually with a little hammer, sonic sensors (receivers) record the signals. Little pins are used for coupling the sensors to the wood. Number and positions of the test points are critical to the accuracy of the scan.
By using both acoustic travel-time information and geometry data of the measuring level the software calcualtes tomograms that show the apparent sonic velocities, thje so called sonic tomograms acoustic tomograms. The speed of sound in wood correlates with wood quality and is therefore a measure for the breakign safety of the trunk. The PiCUS sonic tomogram shows the residual wall thickness. Using this information the calculations o