Evaluation of an automated hardwood lumber grading system
Over the last 10 years, scientists at the Thomas M. Brooks Forest Products Center, the Bradley Department of Electrical Engineering, and the USDA Forest Service have been working on lumber scanning systems that can accurately locate and identify defects in hardwood lumber. Current R&D efforts are targeted toward developing automated lumber grading technologies. The objective of this work is to evaluate hardwood lumber grading accuracy based on current state-of-the-art multiple sensor scanning technology that uses laser profile detectors, color cameras, and an x-ray scanner. 89 red oak boards were scanned and graded using Virginia Tech’s scanning system. A certified National Hardwood Lumber Association (NHLA) employed lumber inspector then graded the lumber. The boards were also manually digitized and mapped for defects.
The automated lumber grading system was found to be 31 percent more accurate than the company line graders. Further, the automated lumber grading system estimated lumber value to within less than 5 percent of the NHLA certified value whereas the line grader overestimated the lumber value by close to 20 percent. Most automated lumber grading discrepancies resulted from board geometry related issues (e.g. board crook, surface measure rounding, calculation of cutting units, etc.). Concerning the multiple sensor scanning system defect recognition improvements should focus on better methods to differentiate surface discoloration from critical grading defects. This study is helping to guide the development of future scanning hardware and image processing software to more accurately identify lumber grading features.
Requesting Print Publications
Publication requests are subject to availability. Fiscal responsibility limits the hardcopies of publications we produce and distribute. Electronic versions of publications may be downloaded, distributed and printed.
Please make any requests at firstname.lastname@example.org.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
- Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact the SRS webmaster if you notice any errors which make this publication unuseable.
- To view this article, download the latest version of Adobe Acrobat Reader.