Using Scientific Instruments to Test "The Da Vinci Code"

Wood identification is one of the important research contents of wood anatomy and wood science. It is mainly used in plant classification, conservation of rare and valuable trees, rational use of wood, search for substitute materials, and protection of the ecological environment. As a by-product, the development of wood identification technology also provides a scientific basis for safeguarding consumer interests and unlocking the “Da Vinci Code” of the furniture industry.

Market needs to crack the method

Da Vinci Home Furnishings Co., Ltd. of Shanghai declared that on its million-dollar furniture, it used a precious timber called the thorns of poplar, which is only found in a remote Italian town. According to CCTV's "Weekly Quality Report" survey, this so-called "precious timber" is just a polymer resin material, large core board and density board.

With the increasing scarcity of precious wood resources, the furniture market is shoddy, and the use of other materials to impersonate wood is also increasing. According to furniture sellers, on the market, wood with a texture similar to that of black walnut, such as oak and manchurian ash, has been used to deceive consumers through the use of dyeing techniques and even used paper materials as teak.

If there is a technical means that can easily and accurately identify the type of wood, place of origin, etc., I believe that the "Da Vinci Code" on the market will be less and less, and the furniture industry will become more and more standardized.

Under the support of the National Natural Science Foundation of China, researchers from the Chinese Academy of Forestry Science, such as Cheng Fang and Yang Zhong, benefited from microscopic image features, infrared spectroscopy, and other techniques to identify wood. Although the original intention of researchers is not furniture identification, the development of wood identification technology will certainly provide consumers with a tool to discriminate against false information.

Provides a way to differentiate tree species

“Our main purpose is to provide a way or means for experts to distinguish between species, like identifying materials used in Da Vinci's furniture, origins, and the like, and it is still impossible to do so.” Cheng Fang said, “We make some microscopic The research on the identification of wood characteristics has great limitations.Wood is a kind of biological material, and its internal structural characteristics are greatly affected by the growth environment, growth position (positive or negative), climate zone, and even a disaster weather. Market-based testing products have a certain degree of difficulty."

And the identification of cultural relics has "ophthalmology" similar to the analysis and identification of scientific instruments. Wood identification can also be divided into macroscopic identification, microscopic identification and assisted identification. Macroscopic identification refers to the identification of the macroscopic structural features of the wood under the naked eye or with the aid of a magnifying glass, generally only identifying large categories of wood. Microscopic identification refers to the microscopic observation of the microstructure of wood cells under a microscope and accordingly identifies wood. Since wood is composed of many cells, microscopic feature recognition is more valuable.

In 2002, with the support of the National Natural Science Foundation of China, Cheng Fang began to identify the characteristics of wood images. They use the wood image's color, grayscale, texture and other content to achieve tree similarity matching search, extracting hue, saturation, brightness, contrast, second-order angular moments, variance, and long stroke aggravation factor, fractal dimension, wavelet level The characteristic parameters such as the proportion of energy are identified based on the principle of maximum similarity mathematics.

“In principle, the microscopic characteristics of different kinds of wood under the microscope are different. What we do is to establish a database of the features of the wood under the microscope, add the camera to the microscope, and identify the wood and database. For comparison, if the similarity reaches a certain range, it is considered to be the same type.” Cheng Fang said.

With the support of the National Natural Science Foundation of China, this project collected and digitized the microscopic features of the 562 broad-leaved trees. In the study of the identification of tube orifice distribution types, the researchers used experiments to use a new image segmentation algorithm that combines the gray-scale mathematical morphology with the maximum variance-like variance method to perform multi-resolution preprocessing on the identified images. , get a good "broad" filter effect.

Through the experimental design of different computer identification processes, the researchers identified the characteristics of the target, through the selection, combination of specific structural elements and morphological operations, and the skeletonization of the binary image, to achieve computer identification of broad-leaved tree cross-section tube hole The three different types and orientations of the directionality, flame shape, and cross-shape of the branches presented by the distribution of the tube holes. It shows that mathematical morphology has good operational flexibility and pertinence in the analysis and identification of wood feature images. Accumulated basic data for wood feature image retrieval techniques.

There is a small step away from the application

In 2009, Yang Zhong, a research fellow at the Institute of Wood Industry of the Chinese Academy of Forestry, applied for the National Natural Science Foundation of China's "Near-infrared Spectroscopy-based Wood Identification Study" project. Yang Zhong began using another method for wood identification and exploration.

“There are many methods for wood species identification, including microscopic image method, genetic method (DNA labeling), chemical method (stability isotope), and near-infrared spectroscopy (NIR) technology. Near-infrared spectroscopy technology is the rapid development of analytical chemistry in recent years. The high-tech analysis technology has been widely used in the fields of food, medicine, and agriculture," said Yang Zhong.

Near-infrared spectroscopy techniques also require spectroscopic analysis of wood and comparisons with tree species information in the database. In 2003, Japanese experts identified eight species of wood using near-infrared spectroscopy. After several years of hard work, the Institute of Wood Industry of the Chinese Academy of Forestry also established a database of near-infrared spectra of more than 20 types of wood, and applied for a patent for the invention's invention of the method for the identification of the near-infrared spectrum of rosewood.

"Infrared spectroscopy has its advantages, but it also has limitations. It doesn't work well for some trees," Yang Zhong said. "The technology needs more spectral data of wood samples to establish a more representative mathematical model." This involves chemometrics and other fields, and we are currently selecting some tree species for verification, but we still cannot identify the species and the place of production. This technology will have the prospect of marketization in the future, but at present it is only basic research, and we are also doing some preliminary research. Exploration."

“We had selected several types of hardwood pipe boreholes with more outstanding structural features to conduct research. But what I really recognise is only a few of them. After the project was finished, I did not conduct any further research in this area. As far as I know The National Natural Science Foundation later funded several projects in this area and they have done a good job. However, at present, computers can only distinguish between classes or genus by automatically identifying wood, Cheng Fang said.