<div dir="ltr">From the code:<br><div><br>result = (nirchan - (greenchan - (bluechan - redchan)))/(nirchan - (greenchan - (bluechan + redchan)));<br><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">
On 10 October 2013 00:07, GRASS GIS <span dir="ltr"><<a href="mailto:trac@osgeo.org" target="_blank">trac@osgeo.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
#2098: <a href="http://i.vi" target="_blank">i.vi</a> gari wrong formula?<br>
-----------------------+----------------------------------------------------<br>
 Reporter:  kristinah  |       Owner:  grass-dev@…<br>
     Type:  defect     |      Status:  new<br>
 Priority:  normal     |   Milestone:  6.4.4<br>
Component:  Default    |     Version:  unspecified<br>
 Keywords:             |    Platform:  Unspecified<br>
      Cpu:  All        |<br>
-----------------------+----------------------------------------------------<br>
 The formula for GARI in the manual<br>
 (<a href="http://grass.osgeo.org/grass70/manuals/i.vi.html" target="_blank">http://grass.osgeo.org/grass70/manuals/i.vi.html</a>) seems to be wrong. As<br>
 it is now, the result would always be 1.<br>
<br>
 It is<br>
 "<br>
 GARI = ( nirchan - (greenchan-(bluechan - redchan))) /<br>
 ( nirchan- (greenchan-(bluechan - redchan)))<br>
 "<br>
<br>
 It should be (e.g. according to<br>
 <a href="http://www.indexdatabase.de/db/i-single.php?id=363" target="_blank">http://www.indexdatabase.de/db/i-single.php?id=363</a>)<br>
 "<br>
 GARI = ( nirchan - (greenchan-(bluechan - redchan))) /<br>
 ( nirchan- (greenchan+(bluechan - redchan)))<br>
 "<br>
<br>
 As the formula in the manual seems to be taken from code, the code might<br>
 be wrong as well. I did not test the function, only read the manual<br>
 online.<br>
<span class="HOEnZb"><font color="#888888"><br>
--<br>
Ticket URL: <<a href="https://trac.osgeo.org/grass/ticket/2098" target="_blank">https://trac.osgeo.org/grass/ticket/2098</a>><br>
GRASS GIS <<a href="http://grass.osgeo.org" target="_blank">http://grass.osgeo.org</a>><br>
<br>
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