Estimating fibre orientation in spruce using lighting direction

Softwood is almost entirely composed of fibres and its physical properties depend on their orientation. A method is proposed to estimate the average fibre orientation at each pixel in the inspection image. In this study it is shown that finished wood has distinctive reflectance properties that are a consequence of the microstructure of the wood surface. If the fibres lie parallel to the image plane these properties can be used to estimate fibre orientation. It is argued that the reflectance behaviour reported in this study generalises to a wide range of materials with directional microstructures.