Chen J.M. & Cihlar J., 1995: Quantifying the effect of canopy architecture on optical measurements of leaf area index using two gap size analysis methods. IEEE Trans. Geosci. Remote Sens. 33, 777-787.

PDF Gonsamo A., Walter J.-M., Chen J.M., Pellikka P. & Schleppi P., 2018: A robust leaf area index algorithm accounting for the expected errors in gap fraction observations. Agric. For. Meteorol., 248: 197-204.

Lang A.R.G., 1987: Simplified estimate of leaf area index from transmittance of the sun's beam. Agric. For. Meteorol. 41, 179-186.

Lang A.R.G. & Xiang Y., 1986: Estimation of leaf area index from transmission of direct sunlight in discontinuous canopies. Agric. For. Meteorol. 37, 229-243.

Miller J.B., 1967: A formula for average foliage density. Aust. J. Bot. 15, 141-144.

Norman J.M. & Campbell G.S., 1989: Canopy structure. In: Plant physiological ecology: field methods and instrumentation, Pearcy R.W., Ehleringer J.R., Mooney H.A. & Rundel P.W. (eds.): 301-325. Chapman and Hall, New York.

Nobis M. & Hunziker U., 2005: Automatic thresholding for hemispherical canopy-photographs based on edge detection. Agric. For. Meteorol. 128, 243-250.

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PDF Schleppi P., Conedera M., Sedivy I. & Thimonier A., 2007: Correcting non-linearity and slope effects in the estimation of the leaf area index of forests from hemispherical photographs. Agric. For. Meteorol. 144: 236-242.
Note: The method published by Schleppi et al. (2007) results in LAI values expressed by unit of inclined ground. Starting with version 2.1, Hemisfer now gives the slope-corrected LAI per unit of projected (horizontal) surface, which is the general standard. See the help about the slope for further explanations.

Steven M.D., Unsworth M.H., 1980: The angular distribution and interception of diffuse solar radiation below overcast skies. Q. J. R. Meteorol. Soc. 103: 457-465.

PDF Thimonier A., Sedivy I., Schleppi P., 2010: Estimating leaf area index in different types of mature forest stands in Switzerland: a comparison of methods. Eur. J. For. Res. 129: 543-562.

Walter J.-M.N., Torquebiau E.F., 2000: The computation of forest leaf area index on slope using fisheye sensors. C. R. Acad. Sci. III 323: 801-813.