Hello, I have seen the TGI formula for Pix4D Fields and a comment in the Fields Support regarding a formula.
I am in mapper, in Index Map and the TGI formula Rgreen - 0.39 * RRED - 0.61* RBLUE that you mention in Fields, does not work.
How do I enter the “normalized to the maximum value of RED, GREEN and BLUE bands”?
Thank you
Hi @jzanelli, Pix4DMapper does not have the min, max functions in the calculator. You will need to use QGIS/ArcGIS or any raster calculator that has these functions. You could also do the same in any programming language. This is how we normalize: we compute the maximum pixel value in the image for the three bands involved. So the formula is (G - 0.39 * R - 0.61 * B) / image_maxpixelvalue(R, G, B)
Ok will do
Hello,
I try to use normalized TGI formaking comparison with pix4d and with others datas.
But…
The normal TGI is :
-0.5*(190*(r-v) - 120*(r-b))
But pix4d TGI is :
(g -0.39 * r -0.61 * b)/max(c(r,v,b))
When I make comparison, I have not strong correlation between this 2 TGI : 0,76
Why ?
Is there something I don’t understand ? Thanks
Hi,
I see they are different formulas, you can estimate the same TGI formula in Pix4D in order to compare with other ones.
Best
José