ndvi {ASIP}R Documentation

Normalized Difference Vegetation Index


Normalized Difference Vegetation Index (NDVI). It is the most widely used satellite image derived index emphasizing on vegetation mapping. This function can also be used to obtain the ground emissivity as well.


ndvi(directory = getwd(), crop = "n", ext2crop = "none",
  op_directory = directory, emissivity = "n")


ext2crop, crop, directory

Same as mentioned in arvi.


Specify the output directory (within double quotes). By default the input satellite image directory will be selected as the output directory.


Assign value "y" to get the emissivity of the surface as a seperate raster file.


File named ndvi_'date of satellite image acqisition'.tif in the input folder


1. NDVI= (r_nir - r_red)/(r_nir + r_red)

where, "r_" denotes TOA reflectance band.

2. Emissivity is calculated according to Van De Griend and Owe (1993).

3. Emissivity values will be absent on pixels with negative NDVI values. This can affect the land surface temperature results (not at-sensor brightness temperature) as well. So, please review the study region and the requirements before using this function.

4. Other important notes are mentioned in custom.eqn.


1. Huetet A R and Jackson R D (1987) Suitability of spectral indices for evaluating vegetation characteristics on arid rangelands, Remote sensing of environment, 23(2), pp:213-232. doi: 10.1016/0034-4257(87)90038-1.

2. Van De Griend AA, Owe M (1993) On the relationship between thermal emissivity and the normalized difference vegetation index for natural surfaces. Int J Remote Sens 14:1119–1131. doi: 10.1080/01431169308904400


library (raster)
library (rgdal)
# Finding the path of the sample satellite image directory.
# User may define paths directly like "/home/ur_folder" or "C:/ur_folder"
path <- system.file ("TM_sample", package = "ASIP")
shapefil <- paste0 (path, "/test.shp")
ndvi (directory = path, crop = "y", ext2crop = shapefil)

[Package ASIP version 0.4.9 Index]