Rado Gazo, Michel Abdul Massih Said, Juraj Vanek, Eva Haviarova, Bedrich Benes. Purdue University

Transcription

1 Rado Gazo, Michel Abdul Massih Said, Juraj Vanek, Eva Haviarova, Bedrich Benes Purdue University

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4 Pioneering contributions to wood science: - Wood truss design for residential and light-frame industrial buildings; - Evaluation of strength properties of structural lumber using machine stress grading; - Design and evaluation of woodbased composite products as well as development of application for their use; - Product engineering, quality improvement, strength design of furniture and its performance.

5 601 firms in the primary industry of Indiana 21,692 individuals are employed by the primary industry $563 million dollars in wages were paid by the primary industry

6 $666 million in wages were paid by the secondary industry 509 firms comprise the secondary wood products manufacturing industry in Indiana 69 of the 300 largest U.S. furniture, cabinet, and millwork manufacturers have plants in Indiana 10 of the largest kitchen cabinet manufacturers have headquarters or plants in Indiana 26,150 individuals are employed by the secondary industry

7 Rado Gazo, Michel Abdul Massih Said, Juraj Vanek, Eva Haviarova, Bedrich Benes Purdue University

8 Log Length: No limit Max. Log Diameter: 700 mm Gantry aperture: 1200 mm Max Log speed: 60 m/min X Y resolution: approx. 1mm

9 LogView TM Veneer (full optimization) Sawmill (full optimization) Developed by Purdue Hardwood Scanning Center Commercialized by LogView, LLC

10 Hardwood Veneer Slicing Optimize splitting log into flitches (off-line or in-line) Hardwood Sawmills - Optimize log opening at headrig to maximize yield of premium product (in-line between debarker and headrig) Log merchandising and bucking

11 Two basic decisions: 1. How to orient the log before sawing into flitches? 2. How to laterally position log on saw carriage?

12 Images courtesy of USDA Forest Service Northeastern Research Station

13 Almost all hardwood lumber in the US is graded according to the NHLA rules Pith is a defect which is allowed in very limited amounts in the highest grades of lumber

14 Locating the pith in the CT scan of the log Pith is rarely at the tree s geometric center Use industrial scanner vs. medical, focus on speed Michel Abdul Massih Said. CS 690.

15 Compute pith position from cross-section images of an entire CT scanned log Visualize pith position on every cross-section image Visualize smallest volume containing the pith position on the entire log Michel Abdul Massih Said. CS 690.

16 Two methods to detect pith Precise & approximate Precise method exact detection of the grow rings center Approximate methods Detection of center from outer log boundary Center as point with lowest density Michel Abdul Massih Said. CS 690.

17 Find edges of image (Canny edge detector) Separable convolution to find gradient magnitude and direction Gets ridges by measuring magnitudes on adjacent pixels on gradient direction Hysteresis (two thresholds to decide if pixels is edge) Original Gradients Detected edges

18 Modified Circle Hough Transform From every edge pixel, draw line in direction of gradient and increase accumulator Find position of highest value in accumulator pith center Michel Abdul Massih Said. CS 690.

19 Gradient detection and Hough Transform is slow Seconds for one slice, minutes for entire log (~1000 slices) on CPU Solution: acceleration on graphic processor (GPU) Implementation of all algorithms in CUDA for parallel processing Speedup: more than 30x 10s to detect pith on entire log (nvidia Quadro K5000) Michel Abdul Massih Said. CS 690.

20 1. Center is average from boundary points Boundary between log scan and background For very noisy data with ring structure not clearly visible 2. Center is the position of lowest density Michel Abdul Massih Said. CS 690.

21 1. Use precise method to detect pith on image 2. Use one of approximate methods to detect pith on next image If distance from result from 1 and 2 > epsilon, use precise method on image 3. Repeat for whole log 4. Correct results by weighted average 5. Compute minimum volume containing pith 6. Visualize Michel Abdul Massih Said. CS 690.

22 Detected pith on various tree species Black Cherry (1) Black Walnut Hard Maple (2) Red Oak (3) White Oak Yellow Poplar (4)

23 Bark Pith Knots Splits Other high density Holes, low density

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26 We annotated manually pith positions in 22 logs from 6 different species We measured average pixel distance from detected pith center 1 pixel ~ 1 mm Michel Abdul Massih Said. CS 690.

27 Y coordinate (pixels) X-coordinate (pixels) Top view Manual Detected Slice Side view Manual Detected Slice Difference between manual and automatic pith detection Black Cherry Michel Abdul Massih Said. CS 690.

28 Species # of logs tested Average distance (mm) Black Cherry Black Walnut Hard Maple Red Oak White Oak Yellow Poplar Michel Abdul Massih Said. CS 690.

29 Fast pith detection (less than 10s on 1000 slices) Three methods to find pith Average distance from real center: less than 1cm Michel Abdul Massih Said. CS 690.