Release notes

2 October 2020: Hemisfer 3.0

As a major new version, Hemisfer 3 offers a new function: it is now possible to analyse pictures of single tree crowns to obtain their leaf area. It may be strange at first glance, but it is much more complicated to estimate the leaf area of a single tree than the leaf area index of a whole forest canopy. Hemisfer 3 can do both. It also enables the user to combine the light regime analysis with a threshold per ring, which was not possible in previous versions. Further, Hemisfer 3 improves some details of the user interface.

29 September 2017: Hemisfer 2.2

A new method based on a robust regression (Gonsamo et al.) has been added to Hemisfer for the calculation of the leaf area index. In its results, version 2.2 also includes the canopy openness as the solid angle proportion of visible sky. (So far, only the proportion of sky in azimuthal equidistant projection was reported as "transmission".) Further, a small inaccuracy in the calculation of the diffuse light regime on a slope was corrected. There was a relative error in the diffuse light index (DLI) of 0.04% by % of slope. This difference should thus be taken into account when comparing older results with results obtained with this new version. When the ground is flat (slope = 0), there is no change in the obtained results.

2 May 2017: Hemisfer 2.17

An error appeared on some computers running Windows 10, preventing Hemisfer to start. Version 2.17 corrects this. It adds also a new language to the user interface: Portuguese.

7 April 2016: Hemisfer 2.16

Since version 2, changing the gamma value during a working session did not have any effect on the threshold calculation according to Nobis & Hunziker (as it should have). In a normal use, gamma is not changed after it has been defined, and in such cases the thereshold was always correct. Version 2.16 now takes any change in the gamma value into account, also within a working session. Further, the p-value for the clumping calculation after Chen & Cihlar is now more strictly defined: in earlier versions, it would have been possible to have a (meaningless) value above 1.

22 March 2016: Hemisfer 2.15

The behaviour or the colour frequency graph (histogramm) was improved for Hemisfer version 2.15, The colour to be ignored is now really ignored also in the theresholding after Ridler & Calvard (1978). Further, a bug in the display introduced in version 2.14 (missing or misplaced rings etc.) was corrected.

15 March 2016: Hemisfer 2.14

Hemisfer version 2.14 brings minor improvements to the user interface.

25 November 2015: Hemisfer 2.13

Hemisfer version 2.13 corrects a bug that produced an error message "index out of range" depending on the lens and on the number of rings. The handling of site coordinates had also to be corrected because "south" and "west" indicators got lost.

25 September 2015: Hemisfer 2.12

Hemisfer version 2.12 brings small improvements to the user interface and corrects a bug that generated an error message when trying to calculate the light regime for sites a high latitudes (>59°).

4 August 2015: Hemisfer 2.11

Hemisfer version 2.11 corrects two small bugs that appeared in some cases when the number of rings was reduced. One of these bugs generated an error message during threshold calcualtion, the other one put the software into a non-responding state (endless loop) when using a single ring but several sectors.

4 May 2015: Hemisfer 2.1

So far, the slope correction used in Hemisfer (based on Schleppi et al., 2007) produced 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. Results from older versions can be converted to this improved calculation method by dividing them by the cosine of the slope. Relative comparisons with the same slope and all calculations of light regimes are unaffected by this change.

2 March 2015: Hemisfer 2.07

Hemisfer 2.07 corrects an error that occured when trying to apply a per-ring threshold on a picture that was actually already black and white only.

10 February 2015: Hemisfer 2.06

When trying to save a new lens geometry, the software appeared to freeze (and came back to life only after switching to another application and back). Hemisfer 2.06 corrects this problem.

10 January 2015: Hemisfer 2.05

Hemisfer 2.05 corrects a bug that the window of the software could have been placed outside the screen (which resulted in an icon in the task bar but no visible Hemisfer window on the screen).

3 November 2014: Hemisfer 2.04

In some cases, Hemisfer caused errors because it did not get the permission from Windows to write the sites and lenses files into its own folder. These files are thus now located within the user's AppData folder (except if the programme folder is writeable for everyone, e.g. in a portable installation on a removeable drive). Version 2.04 further corrects an error message that could appear when sectors were used at the same time as the calculation of the light regime.

2 October 2014: Hemisfer 2.03

Version 2.03 corrects a problem with the colour to be ignored. When painting zones to be ignored on a picture, it is possible to specify a tolerance because non-conservative picture formats like JPEG do not keep the colours exactly. The calculation of this tolerance was wrong (too much tolerance) in the preceding versions 2.x.

4 September 2014: Hemisfer 2.02

Depending on the country and language settings of Windows, text files (lenses, sites, parameters) were not always correctly read. This is corrected by the new release. Automatic saving of parameter (INI) files did not work properly and this is now also improved. Further, it is now possible to install the new version without uninstalling the old one (existing lenses and sites files are thereby preserved).

21 August 2014: Hemisfer 2.01

This corrects a a bug in version 2: diffuse normal radiation was not properly reset between the analysis of pictures within a batch analysis.

18 August 2014: Hemisfer 2

Version 2 is finally available. It has two main new features. First it can now make a local analysis of the light regime at the point where a hemispherical picture was taken. Second, it runs properly on newer versions of Windows (7, 8). Older registrations are still valid for this version. Note that INI parameter files from version 2 will not be usable with older versions of the software. The compatibility is only "upward": older parameter files can be read in Hemisfer 2.

24 February 2011: Hemisfer 1.53

This version corrects a bug that affected the calculation of the lens geometry for some lenses. Nikon FC-E9 was slightly affected, Raynox DCR-CF185 more. Users who worked with these lenses or with parameters not provided with Hemisfer are advised to check the results obtained with previous versions as they may be inaccurate.

16 August 2010: Hemisfer 1.52

This version corrects the fact that the suffix .INI got lost when parameter files were generated automatically. It also avoids an unnecessary error message when the foliage angle is estimated to 90°.

29 June 2010: Hemisfer 1.51

There was a bug in the previous versions, affecting the correction of canopy clumping after Chen & Cihlar (1995) when there was a colour to be ignored in the photographs. These two options worked well separately, but when combined they gave too high LAI values. Version 1.51 corrects this bug.

27 April 2010: Hemisfer 1.5

With this version, the gap fraction in vertical direction can now be calculated out of the obtained LAI and leaf angle. This gives also the canopy cover, which is defined as the proportion of the forest floor covered by the vertical projection of the canopy. The same calculation can be done for the fraction of large gaps. Further, it is now possible to constrain the mean leaf angle to a defined range. The user interface received small improvements.

30 July 2009: Hemisfer 1.44

This version adds the possibility to get (uncorrected) LAI values per sector.

4 June 2008: Hemisfer 1.43

This version corrects two small bugs (which affected the user interface, not the calculations). Results without slope correction are now always displayed, also (for comparison) along with slope-corrected results.

15 April 2008: Hemisfer 1.42

This version corrects a bug in the error handling that caused the software to crash when encountering some error situations (e.g. image file not found).

27 August 2007: Hemisfer 1.41

This version corrects a problem with the synthesis of results across several sites. The data were not correctly reset between sites and the systheses of subsequent sites were therefore wrong. The results of individual pictures as well as the synthesis of the first (or single) site analysed in a run were right and thus remain unchanged in this version.

6 June 2007: Hemisfer 1.4

Two new methods were integrated for correcting the effect of canopy clumping (Lang & Xiang, 1986) or clumping and ground slope (Walter & Torquebiau, 2000) . These methods can now be chosen instead of the already available corrections of ground slope (Schleppi et al., 2007) and clumping (Chen & Cihlar, 1995). This latter method was improved and may thus give slightly different results compared to previous versions. The clumping factor O (Omega) was used correctly, but given as its inverse 1/O in the results; this is now corrected. The lens formula in the help was corrected (radius r and angle T were exchanged).

The internalisation was improved and Hemisfer should now run without problem on computers using the comma instead of the dot as decimal separator. Parameter files may however not be exchanged between one system and the other. Further minor improvements were made to the user interface.

9 May 2006: Hemisfer 1.3

Tests with artificial pictures revealed a small error in the weight of the different rings when zones of the picture have to be ignored. This error affected pictures with zones painted with a color to be ignored as well as pictures where the soil is visible in the analysis rings because of a ground slope. Users who analysed such pictures are advised to repeat the calculation with the version 1.3 and see if this error is important in their case. If no pixels were ignored, then the results are not affected. Version 1.3 also corrects a bug causing the programme to crash when minimised. It brings further minor improvements to the error handling and to the user interface.

28 October 2005: Hemisfer 1.2

Version 1.2 now includes a graph of colour frequencies, the definition of the north on the picture, the support of lenses with a viewing angle less than 180 degrees and a second thresholding method (Ridler & Calvard, 1978), beneath the already provided method (Nobis & Hunziker, 2005). It also corrects problems encountered when changing the language and brings minor improvements of the user interface, including a better handling of run-time errors.

6 September 2005: Hemisfer 1.11

The parameter save button was not always enabled as it should have been. Revision 1.11 corrects this.

30 August 2005: Hemisfer 1.1

Version 1.1 mainly corrects a bug which caused a wrong display of the picture when zooming out, or even let the programme crash. Some details of the user interface were also improved.

11 July 2005: Hemisfer 1.0

Version 1 of Hemisfer is released as a shareware for the calculation of LAI from hemispherical photographs of plant canopies.