calcIndices: Calculate spectral indices from multispectral data
In mqueinnec/foster: Forest Structure Extrapolation with R

Description Usage Arguments Details Value See Also Examples

Calculate spectral indices (e.g. NDVI, tasseled cap coefficients etc.) from multispectral data. Calculations are based on the functions spectralIndices and tasseledCap. Refer to the documentation of these functions for more details.

calcIndices(
  x,
  indices = "NDVI",
  sat = NULL,
  blue = NULL,
  green = NULL,
  red = NULL,
  nir = NULL,
  swir1 = NULL,
  swir2 = NULL,
  swir3 = NULL,
  coefs = list(L = 0.5, G = 2.5, L_evi = 1, C1 = 6, C2 = 7.5, s = 1, swir2ccc = NULL,
    swir2coc = NULL),
  filename = "",
  par = FALSE,
  threads = 2,
  m = 2,
  progress = TRUE,
  ...
)

`x`	Raster* or SpatialPointsDataFrame object or list of Raster* or SpatialPointsDataFrame objects.
`indices`	Character vector indicating Which indices are calculated. Tasseled Cap indices are abbreviated as `TCB`, `TCW`, `TCG`, `TCA`, `TCD`. For a list of other supported indices see `spectralIndices`
`sat`	Character. If calculating tasseled cap indices, name of the sensor needs to be provided. One of: c("Landsat4TM", "Landsat5TM", "Landsat7ETM", "Landsat8OLI", "MODIS", "QuickBird", "Spot5", "RapidEye"). See `tasseledCap`.
`blue`	Integer. Blue band.
`green`	Integer. Green band.
`red`	Integer. Red band.
`nir`	Integer. Near infrared band (700-1100 nm).
`swir1`	temporarily deprecated
`swir2`	Integer. Shortwave infrared band (1400-1800 nm)
`swir3`	Integer. Shortwave infrared band (2000-2500 nm)
`coefs`	Coefficients necessary to calculate some of the spectral indices (e.g. EVI). See `spectralIndices`.
`filename`	Character. Output file name including path to directory and eventually extension. If `x` is a list, `filename` must be a vector of characters with one file name for each element of x. Default is `""` (output not written to disk).
`par`	Logical. Should the function be executed on parallel threads
`threads`	Number of parallel threads used if par = TRUE
`m`	tuning parameter to determine how many blocks will be used (m blocks will be processed by each cluster)
`progress`	Logical. If TRUE (default) a progress bar is displayed when using parallel processing.
`...`	Other arguments passed to `writeRaster` or `writeOGR`.

If x is a Raster* or list of Raster* objects, each layer should be one of the spectral bands used to calculate the indices. If x is a SpatialPointsDataFrame or list of spatialPointsDataFrame, each column should be a spectral band. When calculating tasseledCap indices, bands should be provided in a specific order specified in tasseledCap.

Tasseled Cap Angle (TCA) and Distance (TCD) are calculated from greenness (TCG) and brightness (TCB) as follows:

TCA = \arctan(\frac{TCG}{TCB})

TCD = √{TCB^{2} + TCG^{2}}

If x is a list of Raster* objects, the processing can be parallelized using cluster. In that case the user has to set par = TRUE and provide the number of parallel threads threads. You can control how many blocks will be processed by each thread by setting m (see cluster).

Raster* or SpatialPointsDataFrame object or list of Raster* or SpatialPointsDataFrame objects.

spectralIndices, tasseledCap, cluster

library(raster)

# Open Landsat BAP image
BAP_2006 <- stack(system.file("extdata/examples/Landsat_BAP_2006.tif",package =
                                "foster"))

# Calculate NDVI
VI_2006 <- calcIndices(BAP_2006,
                       indices = "NDVI",
                       red=3,
                       nir=4)