HSP – HemiSPherical Project Manager, a program for processing digital hemispherical images
The amount of green leaves conducting photosynthesis is one of the most important variables in
plant canopies. To describe the amount of leaves, leaf area index (LAI) was defined by Watson
(1947) as the total one sided area of leaf tissue per unit ground surface area. The value of LAI
depends on definition of leaf or needle area (Sellin, 2001; Flower-Ellis and Olsson, 1993). Half of
total area is usually used for flat leaves and projection are is used for needles.
The HSP software implements new approach to measure canopy gap fraction by using a linear
conversion of digital hemispherical images as proposed by Cescatti (2007) where the above canopy
reference measurements are restored from below canopy images according to Lang et al. (2010).
The solution is almost independent from operator subjectivity and relies on the capability of the
modern digital cameras to store unprocessed sensor readings (raw data) in addition to common tiff
of jpeg images.
Lang, M., Kuusk, A., Mõttus, M., Rautiainen, M., and Nilson, T. (2010). Canopy gap fraction estimation from digital hemispherical images using sky radiance models and a linear conversion method. Agricultural and Forest Meteorology, 150(1), 20-29.