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Geological Spectral Indices (GSI)

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.

How to Use the Geological Spectral Indices (GSI) Layer?

  1. Go to the Data tab, expand Geological Spectral Indices, and click Add layer next to the index you want to analyze.
  2. Use the sliders to adjust the value range. The higher the index value, the greater the relative abundance of the mineral phase.
  3. Customize the layer appearance by changing its color or switching to gradient mode in the layer properties.