dn2toa: DN to TOA conversion of optical bands
In ASIP: Automated Satellite Image Processing

Description Usage Arguments Value Note References Examples

Digital number (DN) bands to Top of Atmosphere (TOA) conversion.

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dn2toa(directory = getwd(), crop = "n", ext2crop = "none",
  op_directory = directory, b1 = 1, b2 = 1, b3 = 1, b4 = 1, b5 = 1,
  b6 = 1, b7 = 1)

`ext2crop, crop, directory`	Same as mentioned in `arvi`.
`op_directory`	Specify the output directory (within double quotes). By default the input satellite image directory will be selected as the output directory.
`b1`	By default Band1 will be processed to TOA reflectance. To cancel production of this band assign value 0.
`b2`	By default Band2 will be processed to TOA reflectance. To cancel production of this band assign value 0.
`b3`	By default Band3 will be processed to TOA reflectance. To cancel production of this band assign value 0.
`b4`	By default Band4 will be processed to TOA reflectance. To cancel production of this band assign value 0.
`b5`	By default Band5 will be processed to TOA reflectance. To cancel production of this band assign value 0.
`b6`	By default Band6 will be processed to TOA reflectance. To cancel production of this band assign value 0.
`b7`	By default Band7 will be processed to TOA reflectance. To cancel production of this band assign value 0.

Each bands selected will produce corresponding image in *.tif format in the input directory.

1. This function followed by multi.indices is recommended only if user is intended to produce multiple indices like ndvi & gemi other than running seperate function for each product to save processing time and resources.

Other important notes are mentioned in custom.eqn.

USGS (2016) Landsat 8 (L8) data users handbook, version 2.

Landsat 7 science data users handbook, NASA. Available at "https://landsat.gsfc.nasa.gov/wp-content/uploads/2016/08/Landsat7_Handbook.pdf".

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")
# Assign 0 values to band names which are not required
dn2toa (path, crop = "f", ext2crop = shapefil, b3=0, b4=0, b5=0, b6 = 0, b7 = 0)