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Features

Hemisfer is a software designed to estimate the leaf area index (LAI) and the light regime from hemispherical (or wide-angle) photographs. It includes the following capabilities:

  • Runs under Windows (XP, Vista, 7 or 8).
  • Hemisfer is multilingual. Following language files are available at present: English, French, German, Italian, Spanish, Swedish, Russian, Ukranian, Turkish, Croatian and Romanic.
  • Hemisfer has an extensive online help (in English only).
  • It works with JPEG, TIFF, PNG, BMP or GIF picure files with 2, 8 or 24 bits per pixel.
  • Pictures can be analysed either individually (interactively) or as a batch (user-unattendend).
  • Information about these pictures can be stored in plain-text (understandable) parameter files and retrieved from there.
  • It can also import HVS parameter files generated by HemiView, a software by Delta-T.
  • Several methods are available to estimate the LAI from the light transmission in rings around the zenith:
    • Miller (1967)
    • Miller (1967) as implemented in the Li-Cor LAI-2000
    • Lang (1987)
    • Norman & Campbell (1989)
    • Thimonier et al. (2010)
  • There is the possibility to take the effect of the ground slope into account by using the algorithm of Schleppi et al. (2007).
  • An algorithm (based on Chen & Cihlar, 1995) is included to separate the gaps out of clumped canopies and to correct for their effect on the LAI calculation. The method of Lang & Xiang (1986) is also available to correct these clumping effects, as well as the method of Walter & Torquebiau (2000), which corrects for both ground slope and canopy clumping.
  • It is possible to calculate the light regime at the location where the photograph was taken. The incident light (diffuse and direct) is modelled at a minute time step over the year and combined with the picture as a mask to produce a below-canopy light regime. Results can be diplayed at different time steps within the daily and yearly cycles.
  • The software is able to calculate the threshold to distinguish between white (sky) and black (canopy) pixels according to the methods of Nobis & Hunziker (2005) or of Ridler & Calvard (1978). The γ (gamma) value of the picture is thereby taken into account, which gives objective and reliable results.
  • Results provided in standard file formats, easy to import into softwares used for further processing (spreadsheets, statistical softwares, graphical softwares).


Note: the free downloadable software is limited to an image analysis within a radius of 500 pixels. This limitation is removed upon registration.

 

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