Geological Spectral Indices

Geological Spectral Indices (GSI) are combinations of reflectance values from two or more wavelengths that indicate the relative abundance of specific features — including lithologies, mineral groups, or individual minerals. They are especially useful in geologically complex areas with diverse alteration zones and mixed mineral compositions.

In TerraEye, GSI layers are calculated from multispectral and hyperspectral satellite data. Each index highlights a different mineralogical characteristic of the surface. The higher the index value, the greater the relative abundance of the specific mineral phase in each pixel.

To start working with GSI results, see How to Use the Geological Spectral Indices (GSI) Layer.