Improving Log Defect Detection

The location, type, and size of defects in hardwood logs affect the value of the resulting lumber, so knowing what’s going on inside the tree before it is sawn is valuable. Turns out, you don’t have to be a superhero with x-ray vision to see inside a tree. Several technologies have been developed to do just that, but they each have their limitations.

High-resolution laser scan image of a log with detected defect areas highlighted and acoustic waves passing through.

High-resolution laser scan image of a log with detected defect areas highlighted and acoustic waves passing through.

High-resolution laser surface scanning of hardwood logs can gather data relating to defects on the surface of the log, which can be used to generate maps of defects inside. However, surface inspection can miss unsound or rotten areas inside the log.

Acoustic evaluation, which involves measuring the speed of sound waves traveling through logs, is very accurate at determining soundness, but provides no data about the location of the defect.

Can combining these methods determine the soundness of a log as well as the location of the defects? FPL researchers are working to find out.

FPL Research Forest Products Technologist Xiping Wang, along with partners at the U.S. Forest Service’s Northern Research Station and the University of Minnesota Duluth Natural Resources Research Institute, are examining the technical feasibility of combining acoustic wave data with high-resolution laser scanning data.

Researchers are hoping to develop a combined scanning approach that uses these data to identify potentially unsound defects and facilitate sawing of each log to optimize value.

See this Research in Progress report for more background information and details on the specific approach of the study.

Congratulations to Dr. Robert J. Ross 2014 Felix Ponder Award of Excellence Recipient

Dr. Robert J. (Bob) Ross of the Forest Products Laboratory (FPL) was awarded the 2014 Felix Ponder Award of Excellence today by FPL and Northern Research Station Director Michael T. Rains. Ross is a Supervisory Research General Engineer and the Project Leader of FPL’s Engineering Properties of Wood, Wood Based Materials and Structures Research Work Unit. He is also an ST (Senior) scientist, which is the highest level that a federal research scientist can achieve. There are only three ST scientists among the 60 scientists at FPL.

“Thanks to all of you, and all you do,” a surprised Ross said. “I really don’t know what to say. So many people do so much more and are more deserving.”

Dr. Robert J. Ross

Dr. Robert J. Ross

During a conference call with NRS and FPL employees, Rains cited just a few of Ross’ endeavors outside the workplace as among the many reasons why “he should be a role model for all of us,” and why Ross “was such a worthy recipient of this honor.”

Ross has served as Project Leader for several Research Work Units at FPL, including its physical and mechanical proprieties testing unit, since 1988. His current research focus is the development and use of nondestructive evaluation technologies for various wood products and structures, from standing trees to historic buildings and ships. He has written or co-authored more than 200 technical reports/articles about nondestructive evaluation and jointly holds 24 U.S. and foreign patents.

In addition to being a science leader, Bob is very supportive of employees with special needs. In collaboration with the Madison Area Rehabilitation Center, Bob has sponsored employees with special needs for a number of years and has fully integrated them into his work unit. He is also very active in the Williamson – Marquette Neighborhood Center (WilMar), where he and other FPL employees prepare a meal on the first Saturday of every month for needy Madison residents. Bob donates significant time and money to Port Saint Vincent de Paul, a shelter that functions as a “port in the storm of life” for low-income men. He is also very active in St. Coletta of Wisconsin, which provides residential and vocational programs for people with developmental disabilities.

This award honors the late Dr. Felix Ponder, Jr., who was a soil scientist with the Forest Service Northern Research Station for more than 30 years. Dr. Ponder combined excellence in science with deep commitment to making a difference in people’s lives. Dr. Ponder worked for 18 years on the campus of Lincoln University in Jefferson City, Mo., serving three years as project leader of the second research work unit in the nation located on the campus of a historically black college or university. His work with students was instrumental in drawing people into natural resource careers.

Ross was presented with a handcrafted walnut pen-and-pencil set which had special significance to Dr. Ponder.


Ultrasonic Based Nondestructive Evaluation Methods for Wood: A Primer and Historical Review


With the recent compilation of 50 years of the NDT International Nondestructive Testing and Evaluation of Wood Symposium Series, the recently published Ultrasonic Based Nondestructive Evaluation Methods for Wood: A Primer and Historical Review examines how the nondestructive testing of wood in all of its forms has changed over the last half century. Authors C. Adam Senalik, Greg Schueneman, and Robert Ross provide a basic primer to nondestructive testing using ultrasonic inspection and provide a comprehensive literature review of the use of ultrasonic techniques in the inspection, characterization, classification, and evaluation of wood and wood products as presented in 50 years of the NDT Wood Symposium series.

Ultrasonic inspection of wood has evolved over a half a century of research and development. In addition to the literature review on ultrasound in wood inspection, this report describes basic ultrasonic inspection techniques and analyses. It contains a list of over one hundred species of wood that have been inspected using ultrasound.

Strength grading, determination of elastic constants, and evaluation of moisture content effects are a few of the fields to which ultrasonic inspection have been successfully applied. The most widespread application of ultrasonic inspection with wood is arguably defect detection. There is an ongoing need to detect and assess defects within standing trees, poles, lumber, structures, and engineered wood products. Increased sensitivity and more accurate approximations of remaining wood strength aid inspectors in evaluating the utility and safety of wood structures. Wood is already the most common building material in the world, but with the increased reliability that comes with advanced ultrasonic inspection techniques, its use can only grow.