Internet publication
Hyperspectral characterisation of natural illumination in woodland and forest environments
- Abstract:
- Light in nature is complex and dynamic, and varies along spectrum, space, direction, and time. While both spectrally resolved measurements and spatially resolved measurements are widely available, spectrally and spatially resolved measurements are technologically more challenging. Here, we present a portable imaging system using off-the-shelf components to capture the full spherical light environment in a spectrally and spatially resolved fashion. The method relies on imaging the 4π-steradian light field reflected from a mirrored chrome sphere using a commercial hyperspectral camera (400-1000 nm) from multiple directions and an image-processing pipeline for extraction of the mirror sphere, removal of saturated pixels, correction of specular reflectance of the sphere, promotion to a high dynamic range, correction of misalignment of images, correction of intensity compression, erasure of the imaging system, unwrapping of the spherical images, filling-in blank regions, and stitching images collected from different angles. We applied our method to Wytham Woods, an ancient semi-natural woodland near Oxford, UK. We acquired a total of 168 images in two sites with low and high abundance of ash, leading to differences in canopy, leading to a total 14 hyperspectral light probes. Our image-processing pipeline corrected small (<3 °) field-based misalignment adequately. Our novel hyperspectral imaging method is adapted for field conditions and opens up novel opportunities for capturing the complex and dynamic nature of the light environment.
- Publication status:
- Not published
- Peer review status:
- Not peer reviewed
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- Files:
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(Preview, Pre-print, pdf, 16.0MB, Terms of use)
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- Publisher copy:
- 10.1101/2021.07.19.452949
Authors
- Publisher:
- bioRxiv
- Publication date:
- 2021-07-20
- Acceptance date:
- 2021-07-20
- DOI:
- Language:
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English
- Keywords:
- Pubs id:
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1189101
- Local pid:
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pubs:1189101
- Deposit date:
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2024-01-08
Terms of use
- Copyright holder:
- Li et al.
- Copyright date:
- 2021
- Rights statement:
- © 2021 The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license.
- Notes:
- This research was funded in whole or in part by the Wellcome Trust (204686/Z/16/Z, 218657/Z/19/Z). For the purpose of Open Access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript (AAM) version arising from this submission.
- Licence:
- CC Attribution (CC BY)
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