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Articles containing the keyword 'near-infrared'

Category : Research article

article id 10331, category Research article
Jussi Juola, Aarne Hovi, Miina Rautiainen. (2020). Multiangular spectra of tree bark for common boreal tree species in Europe. Silva Fennica vol. 54 no. 4 article id 10331. https://doi.org/10.14214/sf.10331
Keywords: classification; reflectance; hyperspectral; imaging spectrometer; near-infrared; SVM; visible
Highlights: Novel multiangular measurement set-up for hyperspectral imaging; Multiangular spectra of silver birch (Betula pendula), Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) stem bark samples were collected; Intra- and interspecific variations in reflectance were analyzed; Demonstration of tree species identification based on stem bark spectra; Collected spectra openly available in SPECCHIO Spectral Information System.
Abstract | Full text in HTML | Full text in PDF | Author Info

Despite the importance of spectral properties of woody tree structures, they are seldom represented in research related to forests, remote sensing, and reflectance modeling. This study presents a novel imaging multiangular measurement set-up that utilizes a mobile handheld hyperspectral camera (Specim IQ, 400–1000 nm), and can measure stem bark spectra in a controlled laboratory setting. We measured multiangular reflectance spectra of silver birch (Betula pendula Roth), Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stem bark, and demonstrated the potential of using bark spectra in identifying tree species using a Support Vector Machine (SVM) based approach. Intraspecific reflectance variability was the lowest in visible (400–700 nm), and the highest in near-infrared (700–1000 nm) wavelength regions. Interspecific variation was the largest in the red, red-edge and near-infrared spectral bands. Spatial variation of reflectance along the tree height and different sides of the stem (north and south) were found. Both birch and pine had increased reflectance in the forward-scattering directions for visible to near-infrared wavelength regions, whilst spruce displayed the same only for the visible wavelength region. In addition, spruce had increased reflectance in the backward-scattering directions. In spite of the intraspecific variations, SVM could identify tree species with 88.8% overall accuracy when using pixel-specific spectra, and with 97.2% overall accuracy when using mean spectra per image. Based on our results it is possible to identify common boreal tree species based on their stem bark spectra using images from mobile hyperspectral cameras.

  • Juola, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland ORCID https://orcid.org/0000-0002-6050-7247 E-mail: jussi.juola@aalto.fi (email)
  • Hovi, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland ORCID https://orcid.org/0000-0002-4384-5279 E-mail: aarne.hovi@aalto.fi
  • Rautiainen, Aalto University, School of Engineering, Department of Built Environment, P.O. Box 14100, FI-00760 Aalto, Finland; Aalto University, School of Electrical Engineering, Department of Electronics and Nanoengineering, P.O. Box 15500, FI-00760 Aalto, Finland ORCID https://orcid.org/0000-0002-6568-3258 E-mail: miina.a.rautiainen@aalto.fi

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