Spectral Analysis

Spectral Analysis is the analysis of geological phenomena (vegetation, soil deposits, etc.) by interpreting the variation in color values from imagery. Since each of the nine Landsat bands are mapped to grayscale, it is possible to interpret, or map, the bands to the red, green, and blue portions of the visible spectrum. For example, band 40 contains the near infrared spectrum, which you can map to red. On the resulting image, the changes in red values would then correspond to the changes in infrared values.

The following are the kinds of spectral analyses you can perform, using the Maplicity client:

NDVI - Normalized Difference Vegetative Index, a measure of the vegetative cover. For Landsat imagery, bands 40 and 30 are used to generate this measure, since these bands best highlight chlorophyll absorption and provide good contrast between vegetation and soil

The NDVI value is calculated as:

NDVI = (B40 - B30) / (B40 + B30)

NBR - Normalized Burn Ratio, a measure of burn severity from fires. For Landsat imagery, bands 40 and 70 are used to generate this measure.

The NBR value is calculated as:

NBR = (B40 - B70) / (B40 + B70)

NDSI - Normalized Difference Vegetative Index, a measure of the snow cover. For Landsat imagery, bands 20 and 50 are used to generate this measure.

The NDSI value is calculated as:

NDSI = (B20 - B50) / (B20 + B50)

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Now you should have some basic background needed to use our map services. Click the following link for information on using our Fire demonstration map service: Map Service for Fire Demonstration