VIDEO—Digitally Imaging Wood, Knots and All

Tokyo, Japan—Researchers at the University of Tokyo and other locations have developed a way to generate graphics that model the annual ring pattern of solid wood, along with natural elements like knots.

Although wood texturing is a well-studied topic, there have been few previous attempts at modeling knots inside the wood texture, according to a paper that will be delivered at Siggraph 2022, a global computer graphics conference taking place this summer in Vancouver. Given the presence of digital wood imaging technology at IWF 2022, as well as recent trends in 3D printed wood products, the new research may be applicable to the wood manufacturing industry.

The method takes the skeletal structure of a tree log as input, and produces a three-dimensional “scalar field,” which refers to the way the program incorporates the variable growth patterns of trees. The program can represent the times of added growth, which defines the volumetric annual ring pattern. Here’s the researchers’ summary of their approach:

First, separate fields are computed around each strand of the skeleton, i.e., the stem and each knot. The strands are then merged into a single field using smooth minimums. We further suggest techniques for controlling the smooth minimum to adjust the balance of smoothness and reproduce the distortion effects observed around dead knots. Our method is implemented as a shader program running on a GPU with computation times of approximately 0.5 s per image and an input data size of 600 KB. We present rendered images of solid wood from pine and spruce as well as plywood and cross-laminated timber (CLT). Our results were evaluated by wood experts, who confirmed the plausibility of the rendered annual ring patterns.

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