[GRASS-dev] [GRASS GIS] #2098: i.vi gari wrong formula?

[GRASS GIS]

#2098: i.vi gari wrong formula?
-----------------------+----------------------------------------------------
 Reporter:  kristinah  |       Owner:  grass-dev@…              
     Type:  defect     |      Status:  new                      
 Priority:  normal     |   Milestone:  6.4.4                    
Component:  Default    |     Version:  unspecified              
 Keywords:             |    Platform:  Unspecified              
      Cpu:  All        |  
-----------------------+----------------------------------------------------
 The formula for GARI in the manual
 (http://grass.osgeo.org/grass70/manuals/i.vi.html) seems to be wrong. As
 it is now, the result would always be 1.

 It is
 "
 GARI = ( nirchan - (greenchan-(bluechan - redchan))) /
 ( nirchan- (greenchan-(bluechan - redchan)))
 "

 It should be (e.g. according to
 http://www.indexdatabase.de/db/i-single.php?id=363)
 "
 GARI = ( nirchan - (greenchan-(bluechan - redchan))) /
 ( nirchan- (greenchan+(bluechan - redchan)))
 "

 As the formula in the manual seems to be taken from code, the code might
 be wrong as well. I did not test the function, only read the manual
 online.

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/2098>
GRASS GIS <http://grass.osgeo.org>