Typo in the i.vi man page

[micha]

I think there's a small error in the equation for MSAVI2 in the man page for i.vi. Here's what appears: MSAVI2 = (1/2)*(2(NIR+1)-sqrt((2*NIR+1)^{2-8(NIR-red)))}

Should be (incorrect parentheses):

MSAVI2 = (1/2)*(2*NIR+1-sqrt((2*NIR+1)^{2-8(NIR-red)))}

Can anyone verify?

[micha]

I see that the source for MSAVI2 in i.vi is consistant with the docs. The equation in the source is:

result=0.5*(2*(nirchan+1)-sqrt((2*nirchan+1)*(2*nirchan+1)-8*(nirchan-redchan)));

whereas in:

Qi, J., Chehbouni, A., Huete, A.R., Kerr, Y.H., Sorooshian, S., 1994. A Modified Soil Adjusted Vegetation Index. REMOTE SENS. ENVIRO 48, 119–126.

The MSAVI2 equation is slightly different. There it's 0.5*(2*nir + 1 - sqrt(...))

??

[ychemin]

it might be a typo indeed. can you correct the source code and submit a revision?

[neteler]

Ticket retargeted after milestone closed

[neteler]

ping

[veroandreo]

In 72549:

i.vi: corrected MSAVI2 equation according to ​https://doi.org/10.1016/0034-4257(94)90134-1, see #3385

[veroandreo]

In 72552:

i.vi: corrected MSAVI2 equation according to ​https://doi.org/10.1016/0034-4257(94)90134-1, see #3385 (trunk, r72549)

[veroandreo]

In 72554:

i.vi: corrected MSAVI2 equation according to ​https://doi.org/10.1016/0034-4257(94)90134-1, fix #3385 (trunk, r72549)