Semi-empirical model for upscaling leaf spectra (SEMULS): a novel approach for modeling canopy spectra from in situ leaf reflectance spectra

Abstract

The use of in situ hyperspectral reflectance and bio-physical measurements has been increasing in forestry. Due to limited physical accessibility in a forest environment, most of the reflectance measurements of trees are acquired at a leaf or bunch of leaves level. A few radiative transfer models are available for upscaling leaf spectra to canopy level. While these models are sophisticated, they retrieve canopy spectra based on certain assumptions. We propose ‘semi-empirical model for upscaling leaf spectra (SEMULS)’ which upscales in situ leaf spectra to canopy level based on the relationship between leaf spectra and its bio-physical parameters. The performance of the model has been quantitatively validated by comparing the upscaled canopy spectra with spectra from – CHRIS hyperspectral imagery acquired concurrently and from the PROSAIL model. Results indicate that the SEMULS retrievals are comparable with image spectra and PROSAIL with additional advantages of not requiring scene-dependent geometric-radiometric parameters and assumptions.

Keywords:

• Hyperspectral remote sensing
• CHRIS-PROBA
• PROSAIL
• spectrum
• biochemical properties
• spectral upscaling

Acknowledgments

Authors also thank Janani Sundar, research scholar, IIIT-H for her help in developing the model.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Authors thank the Department of Science and Technology, Government of India, for sponsoring this research work.