spatialEco (version 1.3-0)

swvi: Senescence weighted Vegetation Index (swvi)

Description

Modified Soil-adjusted Vegetation Index (MSAVI) or Modified Triangular Vegetation Index 2 (MTVI) weighted by the Normalized difference senescent vegetation index (NDSVI)

Usage

swvi(
  red,
  nir,
  swir,
  green = NULL,
  mtvi = FALSE,
  senescence = 0,
  threshold = NULL,
  weight.factor = NULL,
  ...
)

Arguments

red

Red band (0.636 - 0.673mm), landsat 5&7 band 3, OLI (landsat 8) band 4

nir

Near infrared band (0.851 - 0.879mm) landsat 5&7 band 4, OLI (landsat 8) band 5

swir

short-wave infrared band 1 (1.566 - 1.651mm), landsat 5&7 band 5, OLI (landsat 8) band 6

green

Green band if MTVI = TRUE

mtvi

(FALSE | TRUE) Use Modified Triangular Vegetation Index 2 instead of MSAVI

senescence

The critical value, in NDSVI, representing senescent vegetation

threshold

Threshold value for defining NA based on < p

weight.factor

Apply partial weights [w * weight.factor] to the NDSVI weights

...

Additional arguments passed to raster calc function

Value

rasterLayer class object of the weighted MSAVI metric

References

Haboudane, D., et al. (2004) Hyperspectral Vegetation Indices and Novel Algorithms for Predicting Green LAI of Crop Canopies: Modeling and Validation in the Context of Precision Agriculture. Remote Sensing of Environment 90:337-352.

Qi J., Chehbouni A., Huete A.R., Kerr Y.H., (1994). Modified Soil Adjusted Vegetation Index (MSAVI). Remote Sens Environ 48:119-126.

Qi J., Kerr Y., Chehbouni A., (1994). External factor consideration in vegetation index development. Proc. of Physical Measurements and Signatures in Remote Sensing, ISPRS, 723-730.

Qi, J., Marsett, R., Moran, M.S., Goodrich, D.C., Heilman, P., Kerr, Y.H., Dedieu, G., Chehbouni, A., Zhang, X.X. (2000). Spatial and temporal dynamics of vegetation in the San Pedro River basin area. Agricultural and Forest Meteorology. 105:55-68.

Examples

# NOT RUN {
library(raster)
library(RStoolbox)

data(lsat)
lsat <- radCor(lsat, metaData = readMeta(system.file(
                 "external/landsat/LT52240631988227CUB02_MTL.txt", 
               package="RStoolbox")), method = "apref")

# Using Modified Soil-adjusted Vegetation Index (MSAVI)
( wmsavi <- swvi(red = lsat[[3]], nir = lsat[[4]], swir = lsat[[5]]) )
    plotRGB(lsat, r=6,g=5,b=2, scale=1, stretch="lin")
      plot(wmsavi, legend=FALSE, col=rev(terrain.colors(100, alpha=0.35)), add=TRUE )

# Using Modified Triangular Vegetation Index 2 (MTVI) 
( wmtvi <- swvi(red = lsat[[3]], nir = lsat[[4]], swir = lsat[[5]],
                          green = lsat[[3]], mtvi = TRUE) )
  plotRGB(lsat, r=6,g=5,b=2, scale=1, stretch="lin")
    plot(wmtvi, legend=FALSE, col=rev(terrain.colors(100, alpha=0.35)), add=TRUE )
# }
# NOT RUN {
# }