calc_savi: Calculate Soil Adjusted Vegetation Index (SAVI)

In GeoIndexR: Computation of Spectral and Geospatial Indices from Multispectral Raster Data

Calculate Soil Adjusted Vegetation Index (SAVI)

Description

Computes the Soil Adjusted Vegetation Index (SAVI) to minimize soil brightness and background influences, using a canopy background adjustment factor L.

Usage

calc_savi(nir, red, L = 0.5)

Arguments

nir	Near-infrared band (terra::SpatRaster or numeric).
red	Red band (terra::SpatRaster or numeric).
L	Soil adjustment factor. Defaults to 0.5.

Details

SAVI = \frac{NIR - RED}{NIR + RED + L} \times (1 + L)

Description & Purpose: In arid, semi-arid, or sparsely vegetated regions, exposed soil background alters red and NIR reflectance, distorting standard vegetation indices like NDVI. SAVI introduces a soil line calibration constant L that stabilizes the index.

Parameter L:

• L = 0.5 (default): Optimal for intermediate to moderate vegetation cover.

• L = 1.0: Recommended for very low / sparse vegetation cover.

• L = 0.25: Recommended for higher vegetation densities.

• When L = 0, SAVI is mathematically identical to NDVI.

Value

A terra::SpatRaster (named "SAVI") or numeric vector with index values.

References

Huete, A. R. (1988). A soil-adjusted vegetation index (SAVI). Remote Sensing of Environment, 25(3), 295-309.

See Also

geo_index, calc_osavi, calc_msavi, calc_ndvi

Examples

# Numeric scalar calculation
calc_savi(nir = 0.7, red = 0.2, L = 0.5)

# Raster layer calculation
img <- get_example_data()
savi_rast <- calc_savi(nir = img[["nir"]], red = img[["red"]], L = 0.5)
print(savi_rast)

GeoIndexR documentation built on Oct. 10, 2026, 5:08 p.m.