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 (Vista, 7, 8 or 10), both in 32-bit and in 64-bit versions (see an example of a screenshot).
- Hemisfer is multilingual. Following language files are available at present: English, French, German, Italian, Spanish, Portuguese, 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 picture files with 2, 8 or 24 bits per pixel.
- Pictures can be analysed either individually (interactively) or as a batch (also user-unattendend... take time for a coffee while it runs these thousands of pictures!).
- Information about these pictures (meta-data) can be stored in plain-text (human-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)
- Gonsamo et al. (2018)
- 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.