Verification technique for a photo-optical volume measuring system for stacks of timber logs

Accurate volume measurement of stacked timber logs is essential for the timber industry. Photo-optical Automated Volume Measuring Systems (AVMS) offer efficient alternatives to manual methods but require verification to ensure reliability. This paper presents a simple, reliable, and easily implementable verification method for AVMS, based on measuring the wood stack front surface area. The proposed method utilizes reference models, calibrated using traceable working standards, to simulate timber log stacks with defined contours. This involves comparing the AVM’s measured area to the reference model’s area, enabling the determination of area measurement errors. The study investigates the selection of reference instruments, proposes a comprehensive AVMS verification procedure, and evaluates the method’s metrological characteristics. Laboratory tests involving 110 AVMS units revealed a repeatability of 0.46% and a total uncertainty of approximately 1.1%. The method successfully identified shortcomings in commercially available AVMS, including non-compliance with manufacturer-declared errors and design imperfections related to camera limitations. The developed method can be used in industry, metrological supervision, and scientific research to ensure accurate and reliable measurements of wood stacks and the long-term reliability of AVMS. This study also highlights the need to further improve photo-optical measurement systems to increase their reliability and accuracy.