i.vi: NDWI unnecessarily requires red band

[sbl]

i.vi requires a red band in any case, even if e.g. NDWI does not need one. So, in order to make the module run, a map has to be given also for the red band. That seems like unexpected behavior to me. Maybe better to leave all input bands optional and add a check for the requested VI if required bands are provided...

[neteler]

Addressed in ​https://github.com/OSGeo/grass/pull/179

[neteler]

Related: also the i.wi addon should be likewise updated:

​https://github.com/OSGeo/grass-addons/blob/master/grass7/imagery/i.wi/main.c

[neteler]

Fixed in

• master: ​https://github.com/OSGeo/grass/commit/c6aa071a25af372bae76915ade947494e8986d53
• relbranch78: ​https://github.com/OSGeo/grass/commit/1905421fe757dfc1121b6ec7bffebfa0f0cbfd99

[sbl]

Personally, I would say, ideally, i.vi and i.wi would be merged into one module e.g. i.spectral.index, where computation of all sorts of spectral indices is collected...

That would be most convenient for users and it would reduce maintenance burden (though the modules would have to be merged first of course). Worth a new ticket?