Vegetation Indices attributes

You can select from several Vegetation Indices (VI) to perform quantitative and qualitative evaluations of vegetation cover, vigor, growth dynamics, and more.

During Attribute Calculation, file metadata is analyzed to identify the sensor type and available bands. Based on the analysis, various VIs become available for which to calculate attributes. The VIs are based on the availability of the following bands:

Red
Green
Blue
Near Infrared (NIR)

Tip: You can calculate additional VIs by running the VEGINDEX algorithm. You can then, in Object Analyst, use the file created by VEGINDEX as input to calculate statistical mean for objects.

If the bands are not defined in the metadata, you can define them.

Vegetation Indices (VI) attributes are independent from the channel aliases and instead rely on the channel metadata or the channels specified as input.

The following table provides descriptions of each Vegetation Index attribute that you can calculate.

Table 1. Vegetation Indices attributes
Attribute	Short name	Description
Green/Red Vegetation Index	GRVI	`GRVI = (Green - Red) ÷ (Green + Red)`
Greenness Index	GI	`GI = ((2.0 × Green) - (Red + Blue)) ÷ ((2.0 × Green) + Red + Blue)`
Vegetation Difference Index	VDI	`VDI = NIR - Red`
Ratio Vegetation Index	RVI	`RVI = NIR ÷ Red`
Normalized Difference Vegetation	NDVI	`NDVI = (NIR - Red) ÷ (NIR + Red)`
Transformed Difference Vegetation Index	TDVI	`TDVI = (NIR - Red) ÷ (NIR + Red) + .5`
Soil Adjusted Vegetation Index	SAVI	`SAVI = ((NIR - Red) ÷ (NIR + Red + L)) × (1 + L)` The `L`-value is based on the amount of green vegetative cover. `L` is a default of 0.5, which means, generally, areas of moderate green vegetative cover.
Modified Soil Adjusted Vegetation Index	MSAVI2	`MSAVI2 = (0.5) × (2(NIR + 1) - √((2 × NIR + 1) - 8(NIR - Red)))`
Global Environmental Monitoring Index	GEMI	`GEMI = eta × (1 - 0.25 × eta) - ((Red - 0.125) ÷ (1 - Red))` Where `eta = (2 × (NIR - Red) + 1.5 × NIR + 0.5 × Red) ÷ (NIR + Red + 0.5)`
Leaf Area Index	LAI	`LAI = (3.618 × EVI) - 0.118` Where `EVI (Enhanced Vegetation Index) = 2.5 × (NIR - Red) ÷ (1 + NIR + (6 × Red) - (7.5 × Blue)`

For more information about segmentation in remote sensing, see the following published work:

Jinru Xue and Baofeng Su, "Significant Remote Sensing Vegetation Indices: A Review of Developments and Applications," Journal of Sensors vol. 2017, Article ID 1353691, 17 pages, 2017.
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