Patent ID: 8394216

Claim:
A method for detecting features on a laminated veneer lumber (LVL) billet, the method comprising: (a) providing a first LVL billet having a length and a width, a first planar surface and a second planar surface; (b) positioning the first LVL billet within a scanning assembly; (c) projecting a first beam of x-ray radiation onto the first planar surface of the first LVL billet substantially across the width of the first LVL billet at a first position along the length of the first LVL billet; (d) measuring the intensity of the first beam of x-ray radiation after is passes through the first and second planar surfaces of the first LVL billet; (e) projecting a second beam of x-ray radiation onto the first planar surface of the first LVL billet substantially across the width of the first LVL billet at a second position along the length of the first LVL billet; (f) measuring the intensity of the second beam of x-ray radiation after is passes through the first and second planar surfaces of the first LVL billet; (g) generating an image of the measured intensity of the first beam of x-ray radiation comprising a plurality of pixels arranged in a first column and generating an image of the measured intensity of the second beam of x-ray radiation comprising a plurality of pixels arranged in a second column, wherein the measured intensity is inversely proportionate to the density of the first LVL billet; (h) calculating the first mean intensity for the first column and calculating the second mean intensity for the second column, and generating an image to display the first and second mean intensities relative to the first and second positions along the length of the first LVL billet; (i) creating a one dimensional array based on the first and second mean intensities; (j) fitting a second order polynomial to the one dimensional array; (k) subtracting the second order polynomial from the one dimensional array to create a difference array; (l) passing the difference array through a low pass filter to create a filtered array; and (m) performing a peak and valley search on the filtered array to identify overlaps or gaps on the first billet.