{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T01:37:15Z","timestamp":1773365835963,"version":"3.50.1"},"reference-count":46,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2016,7,14]],"date-time":"2016-07-14T00:00:00Z","timestamp":1468454400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"NASA HyspIRI Mission","award":["NNX12AQ24G"],"award-info":[{"award-number":["NNX12AQ24G"]}]},{"name":"National Science Foundation Graduate Research Fellowship","award":["DGE-1102937"],"award-info":[{"award-number":["DGE-1102937"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In support of NASA\u2019s next-generation spectrometer\u2014the Hyperspectral Infrared Imager (HyspIRI)\u2014we are working towards assessing sub-pixel vegetation structure from imaging spectroscopy data. Of particular interest is Leaf Area Index (LAI), which is an informative, yet notoriously challenging parameter to efficiently measure in situ. While photosynthetically-active radiation (PAR) sensors have been validated for measuring crop LAI, there is limited literature on the efficacy of PAR-based LAI measurement in the forest environment. This study (i) validates PAR-based LAI measurement in forest environments, and (ii) proposes a suitable collection protocol, which balances efficiency with measurement variation, e.g., due to sun flecks and various-sized canopy gaps. A synthetic PAR sensor model was developed in the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model and used to validate LAI measurement based on first-principles and explicitly-known leaf geometry. Simulated collection parameters were adjusted to empirically identify optimal collection protocols. These collection protocols were then validated in the field by correlating PAR-based LAI measurement to the normalized difference vegetation index (NDVI) extracted from the \u201cclassic\u201d Airborne Visible Infrared Imaging Spectrometer (AVIRIS-C) data (    R 2     was 0.61). The results indicate that our proposed collecting protocol is suitable for measuring the LAI of sparse forest (LAI &lt; 3\u20135 (     m 2  \/  m 2     )).<\/jats:p>","DOI":"10.3390\/s16071092","type":"journal-article","created":{"date-parts":[[2016,7,14]],"date-time":"2016-07-14T10:25:08Z","timestamp":1468491908000},"page":"1092","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Towards an Improved LAI Collection Protocol via Simulated and Field-Based PAR Sensing"],"prefix":"10.3390","volume":"16","author":[{"given":"Wei","family":"Yao","sequence":"first","affiliation":[{"name":"Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA"}]},{"given":"David","family":"Kelbe","sequence":"additional","affiliation":[{"name":"Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2572-2088","authenticated-orcid":false,"given":"Martin","family":"Leeuwen","sequence":"additional","affiliation":[{"name":"Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA"},{"name":"Department of Geography, University College London, Pearson Building, Gower Street, London WC1E 6BT, UK"}]},{"given":"Paul","family":"Romanczyk","sequence":"additional","affiliation":[{"name":"Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA"}]},{"given":"Jan","family":"Aardt","sequence":"additional","affiliation":[{"name":"Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623, USA"}]}],"member":"1968","published-online":{"date-parts":[[2016,7,14]]},"reference":[{"key":"ref_1","unstructured":"Hook, S.J., Turpie, K., Veraverbeke, S., Wright, R., Anderson, M., Prakash, A., Mars, J., and Quattrochi, D. (2014). 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