AnsweredAssumed Answered

Why does my raster calculator output give a black raster after using Exp?

Question asked by farah93 on Oct 9, 2017
Latest reply on Oct 9, 2017 by Dan_Patterson

Hello everyone,

 

I am trying to add multiple raster layers and multiply them by the coefficients of the equation derived by logistic regression. However, when I do add the rasters, I just get a black raster with 0 pixel values. How can I get a raster with 0 to 1 values?

 

I am attaching a snapshot of the max and min values of my rasters and also the logistic regression equation. I have tried breaking down the equation and only performing the portion inside the Exp and that seemed to look reasonable but using the Exp function is what causes problems. (By the way, I have changed the raster names properly in raster calculator so this isn't an issue).

 

Logistic regression equation:

 

1 / (1 + Exp( - (11.97 - 0.000038 * "pop_centres" - 1.6 * "NDVI_2013" - 0.0053 * "Dem30v3proj" - 0.19 * "Slope30v3" - 0.000015  * "Camps30" - 0.032 * "June_prec" - 3.47 * "june_vappres" -  0.000127  * "EUC_2013")))

 

 

Screenshot of some of the explanatory layers

Outcomes