Geodaysit 2023

Assessing transferability of Gaussian Process Regression for Canopy Chlorophyll Content and Leaf Area Index estimation from Sentinel-2 data exploiting a multi-site, year and crop dataset
06-13, 18:00–18:15 (Europe/London), Sala Biblioteca @ PoliBa

Authors: Margherita De Peppo, Francesco Nutini, Alberto Crema, Gabriele Candiani, Giovanni Antonio Re, Federico Sanna, Carla Cesaraccio, Beniamino Gioli, Mirco Boschetti

Spatio-temporal estimation of crop bio-parameters (BioPar) is required for agroecosystem management and monitoring. BioPar such as Canopy Chlorophyll Content (CCC) and Leaf Area Index (LAI) contribute to assess plant physiological status and health at leaf and canopy level. Remote sensing provides an effective way to spatially explicitly retrieve CCC and LAI at different spatial and temporal scales. Several studies demonstrated how Machine Learning (ML) techniques outperform traditional empirical approaches based on Vegetation Index in BioPar estimations from RS data. Among the different available algorithms Gaussian processes regression (GPR) is considered promising for LAI and CCC mapping. However, few of these studies have examined the performance of GPR in predicting crop parameters when applied to different site, season and crop typology (i.e. validation using independent dataset). The specific objectives of this study conducted in the framework of E-CROPS project were: (i) develop a transferable GPR algorithm for LAI and CCC estimation by exploiting a robust multi-crop, multi-year and site dataset; (ii) assess GPR BioPar retrieval performance against ground measurements acquired over independent dataset; (iii) compare result with other methods including empirically based VI models and operational product embedded in SNAP. In total, 209 (CCC) and 301 (LAI) observations were used to train GPR models. Then, over the unseen dataset (LAI n=820 and CCC n=305) the GPR was validated. The results showed that for both LAI and CCC GPR retrieval are reliable and comparable with SNAP estimates despite CCC show a consistent underestimation. LAI (CCC) estimation metrics ranges for the different data sets as follows: R2 0.2 to 0.75 (0.2 -0.7) and MAE 0.1 to 0.75 (0.5-3). Overall the results demonstrated the potentiality of GPR machine learning approach in LAI and CCC estimations when a robust training set is exploited, such condition guarantee a spatial-temporal transferability of the developed model. GPR BioPar estimation from Sentinel 2 can produce decametric quasi-weekly quantitative information for crop spatio-temporal monitoring. Such maps are a fundamental input for decision support systems devoted to smart crop management and early warning indication. Many precision agriculture techniques could thus benefit from information generated with ideal quality and frequency for site-specific practices aimed at reducing inputs and improving the use-efficiency of fertilizers.

Mirco Boschetti received the Laurea Degree (summa cum laude) in Scienze Ambientali (1998) from the University of Milano Bicocca. He got the PhD from the State University of Milan (Agronomy faculty) with the thesis "Use of Remote Sensing and Crop Growth Model to monitor vegetation compound and cropping system". He has been with the National Research Council (CNR) of Italy since 1999 and he is a researcher at IREA since 2010. His research activity regards the use of remote sensing for vegetation and agro-ecosystem monitoring and the definition of environmental indicator through geographic multisource data integration. He has worked on automatic interpretation methods of multispectral and hyperspectral images acquired by airplane or satellite platform for the retrieval of bio-physical parameters and land cover mapping. In the last few years he is working on vegetation phenological parameters estimation, crop mapping and agro-practises monitoring from time series of low-resolution images. M.B. is member of the Scientific Board of the Italian Association of Remote Sensing (AIT). He is a reviewer of several Peer Review International Journal in the GIS, Remote Sensing, Environmental and Agronomical field. He participated at national (Ministry of Environment, Italian Space Agency) and international research programmes (EC, ESA). He was involved in the EU project "GEOLAND” and “GEOLAND2: towards a GMES Land Monitoring Core Service" (2008-2012, EU FP-7). Visiting scientist (in 2010) at IRRI head quarter (Los Banos, Philippines). Independent expert for the audit in the scope of the product and service independent evaluation of the Global land Component of the GIO Land service from 2015 -2017. He has been the coordinator of the FP7 SPACE project ERMES “An Earth obseRvation Model based RicE information Service”. Scientific responsible of the collaboration Framework between CNR-IREA and Bonifiche Ferraresi for research activities and technology transfer in ITC ad Remote Sensing for Precision Farming (2017 – 2020). WP leader of the project CHIME-RCS (2018 2019) and CCN (2019-2021) between ESA and ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale) for the consolidation of requirement for Copernicus CHIME hyperspectral mission. Part of the CNR science team for the activities of CAL/VAL of PRISMA data for the Italian Space Agency (2019-2021). Since 2020 contract professor at University of Milan for the course “Geomatic: remote sensing for agriculture” ( .

This speaker also appears in: