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Using dense X-ray reconstructions for developing virtual sawing method
Kunda, Matej ; Nosko, Svetozár (oponent) ; Zemčík, Pavel (vedoucí práce)
The usage of machine learning and computer optimisation is growing and reaches many fields, and the sawmilling industry is no exception. With optimisation algorithms and virtual sawing, sawmills can produce boards and other wooden products of much higher quality. The main factor that degrades the quality of boards is knots. Knots are the leftovers of branches present in every piece of log and sawn boards. However, their position can be altered with sawing optimisation methods, and the board grade and price maximised. This Master's thesis aimed to develop one of the sawing optimisation methods -- sawing angle optimisation. Before sawing, the log can be rotated, and the location of knots on boards can be controlled. The optimisation method works by converting X-ray data to a function that represents knot locations along the polar angles in the wood and another function that contains Gaussian curves at the corner points of boards in the sawing pattern. Finally, a cross-correlation is computed and minimised between these two functions, resulting in knots avoiding the corner areas. The proposed method works on a simple principle, is computationally effective and can be deployed in real-time applications. The developed method was evaluated by applying virtual sawing using the angles obtained on a challenging dataset containing annotated X-ray data of logs, which was compared with ground truth data and an average result. The thesis resulted in an impressive decrease in arris knots count in an already highly optimised sawing environment.
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