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.