Mask from polygon feature class

Question

Hi everyone,

I am new to ArcGIS and I need to perform a spectral index on dataset of Landsat images. This index performs better when done in a mask. The shapefile I want to use as a mask is a binary raster polygon, (0 and 1) where I want to perform the index on the polygons with the "1" value. Is that mask simply specified in the environments prior to execute the index, or is more complicated?

thanks!

DanPatterson_Retired · Accepted Answer

in the environments.  You can set the mask to anything you want depending on the function to obliterate what is underneath.  So functions might prefer nodata cells since they might not perform calculations in areas of nodata.  Others can be used in an operation involving a product since 0 times something gives 0 (unless of course you already have 0 in the data set.  So specify what you want depending on what you want to keep and what you are doing