This function implements empirical models to estimate LAI (Leaf Area Index) for satellital images. Models were extracted from METRIC publications and other works developed on different crops.
LAI(method = "metric2010", image, aoi, L = 0.1)Method used to estimate LAI from spectral data.
image. top-of-atmosphere reflectance for method=="metric" | method=="metric2010" | method=="MCB"; surface reflectance for method = "turner". Digital counts for method = "vineyard".
area of interest to crop images, if waterOptions("autoAoi") == TRUE will look for any object called aoi on .GlobalEnv
L factor used in method = "metric" or "metric2010" to estimate SAVI, defaults to 0.1
LAI is computed using the top-of atmosphere (at-satellite) reflectance value. LAI and other indices such NDVI, SAVI are used to predict characteristics of vegetation, depending on preferences of the user. Available methods are: "metric", "metric2010", "MCB", "vineyard" and "turner".
R. G. Allen, M. Tasumi, and R. Trezza, "Satellite-based energy balance for mapping evapotranspiration with internalized calibration (METRIC) - Model" Journal of Irrigation and Drainage Engineering, vol. 133, p. 380, 2007 Carrasco-Benavides, M., Ortega-Farias, S., Lagos, L., Kleissl, J., Morales-Salinas, L., & Kilic, A. (2014). Parameterization of the Satellite-Based Model (METRIC) for the Estimation of Instantaneous Surface Energy Balance Components over a Drip-Irrigated Vineyard. Remote Sensing, 6(11), 11342-11371. http://doi.org/10.3390/rs61111342 Johnson, L. F. (2003). Temporal Stability of the NDVI-LAI Relationship in a Napa Valley Vineyard, 96-101. http://doi.org/10.1111/j.1755-0238.2003.tb00258.x Turner, D. P., Cohen, W. B., Kennedy, R. E., Fassnacht, K. S., & Briggs, J. M. (1999). Relationships between leaf area index and Landsat TM spectral vegetation indices across three temperate zone sites. Remote Sensing of Environment, 70(1), 52<U+2013>68. http://doi.org/10.1016/S0034-4257(99)00057-7
Other net radiation related functions: METRICtopo,
SWtrasmisivity, albedo,
incLWradiation,
incSWradiation, netRadiation,
outLWradiation, soilHeatFlux,
solarAngles,
surfaceTemperature