Near Infrared Hyperspectral Imaging in Transmission Mode: Assessing the Weathering of Thin Wood Samples

Smeland, Knut Arne; Liland, Kristian Hovde; Sandak, Jakub; Sandak, Anna; Gobakken, Lone Ross; Thiis, Thomas K.; Burud, I.

doi:10.1255/jnirs.1253

Cited by 18 publications

(12 citation statements)

References 17 publications

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“…earlywood and latewood). 16,17 Understanding of the weathering kinetics of earlywood and latewood separately is important for realistic simulations of wood patterns, thus improving the quality of the architectural rendering. For this purpose, several spectroscopic techniques can be used, such as Fourier-transform near infrared spectroscopy and hyperspectral imaging.…”

Section: Introductionmentioning

confidence: 99%

Chemical and appearance changes of wood due to artificial weathering – Dose–response model

Petrillo

Sandak

Grossi

et al. 2019

Journal of Near Infrared Spectroscopy

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The aim of this study was to assess a model for the surface degradation kinetics of natural wood exposed to artificial weathering. The photochemical and physical processes of weathering result in simultaneous changes of both the wood matrix composition (i.e. lignin content, cellulose crystallinity index, cellulose polymerization degree) and wood's appearance (i.e. colour, gloss, roughness). European larch, a popular cladding material, was used for experimental samples. Weathering was conducted in a QUV artificial weathering machine for 672 h according to the EN927-6 standard. The response of wood was assessed using multi-sensor measurements. Results revealed that changes in colour are evident already after 28 h of artificial weathering, with an increase in a Ã and b Ã , and a decrease in L Ã. That initial trend was reversed afterward, with the colour changing to grey. Due to the particular shape of the curves representing colour coordinates, it is difficult to use CIE L Ã a Ã b Ã parameters to model the weathering dose. However, the degradation curve established for selected near infrared bands was useful to build a dose-response model of wood surface degradation. In all cases, a clear trend of change in absorbance values that progressed along with the weathering dose was observed. These curves, unlike the CIE L Ã a Ã b Ã values, are monotonic, meaning that dose value corresponded with only one value of absorbance. Principal component analysis of the near infrared spectra allowed clustering of the spectra by different dose classes, with the main differentiation in the reference class and in the final class (maximum dose). It was found that the discrimination between spectra at diverse cumulative weathering doses was more evident for earlywood than for latewood. This confirms the hypothesis that degradation kinetics differ depending on the anatomical configuration of wood. This research is a first step for establishing dose-response model for natural weathering, where precise quantification of weathering parameters is more challenging.

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Section: Introductionmentioning

confidence: 99%

Chemical and appearance changes of wood due to artificial weathering – Dose–response model

Petrillo

Sandak

Grossi

et al. 2019

Journal of Near Infrared Spectroscopy

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“…They reported validations with high prediction accuracy indicating that hyperspectral imaging has a high potential for monitoring the water distribution of wood. Smeland et al (2016) studied the weather degradation effects on thin wood samples exposed outdoors from 0 days to 21 days and to ultraviolet (UV) radiation in a laboratory chamber using a hyperspectral camera in the NIR wavelength range (in transmission mode). They presented robust prediction models for weathering effects on wooden surfaces from spectra of earlywood and latewood extracted from the hyperspectral image cubes using different regression techniques.…”

Section: Hyperspectral Imagingmentioning

confidence: 99%

Challenges in the use of Near Infrared Spectroscopy for improving wood quality: A review

2018

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Aims of study: Forestry-related companies require quality monitoring methods capable to pass a large number of samples. This review paper is dealing with the utilization of near infrared (NIR) technique for wood analysis.Area of study: We have a global point of view for NIR applications and characterization of different kind of wood species is considered.Material and methods: NIR spectroscopy is a fast, non-destructive technique, applicable to any biological material, demanding little or no sample preparation. NIR spectroscopy and multivariate analysis serve well in laboratories where the conditions are controlled. The main challenges to NIR spectroscopy technique in field conditions are moisture content and portability.Results: In this review, the methods and challenges for successfully applying NIR spectroscopy in the field of wood characterization are presented. Portable equipment need to record NIR spectra with low noise and low sensitivity to temperature and humidity variations of the air in forest environments. Studies concerning the sample preparation effects on the robustness of the calibrations are thus required.Research highlights: This paper examines traditional applications and practical aspects as well as innovative modern adaptations applied, for example, in hyperspectral imaging and genetic studies.Additional keywords: Near Infrared Spectroscopy; wood properties; moisture; pulp; camera hyperspectral, genetic studies. Abbreviations used: MC (moisture content); PCR (principal component regression); PLS (least squares regression); R² (coefficient of determination); RMSECV (root mean square error of cross validation); r²p (determination coefficient in test set validation); RDP (ratio of performance to deviation); UV (ultraviolet); S/G (syringyl to guaiacyl ratio).

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“…This is used to detect spectral changes in transmission [11]. Examples include assessment of wood quality [12], detecting inter-ocular tumours [13,14] and food quality inspection [15,16,17]. As in the case of thermography, the SNR of such measurements can be improved using lock-in techniques [18].…”

Section: Introductionmentioning

confidence: 99%

Multi-spectral near infrared NDE of polymer composites

Senni

Laureti

Rizwan

et al. 2019

NDT & E International

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Near infrared signals have been used to generate images of the internal structure of fibre-reinforced polymer and foam-filled honeycomb samples. Several different measurement configurations have been investigated, including the use of both modulated light-emitting diodes at discrete wavelengths and broad bandwidth illumination. It is shown that transmission through the samples is wavelengthdependent, and that artificial defects can be detected within polymer composite materials. In addition, wavelength-dependent properties have been used to detect changes due to water ingress into both composite materials and a solar panel structure, leading to a non-contact NDE technique.

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Near Infrared Hyperspectral Imaging in Transmission Mode: Assessing the Weathering of Thin Wood Samples

Cited by 18 publications

References 17 publications

Chemical and appearance changes of wood due to artificial weathering – Dose–response model

Chemical and appearance changes of wood due to artificial weathering – Dose–response model

Challenges in the use of Near Infrared Spectroscopy for improving wood quality: A review

Multi-spectral near infrared NDE of polymer composites

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