MODIStsp_process_QA_bits: MODIStsp helper function to compute Quality Indicators from...
In MODIStsp: Find, Download and Process MODIS Land Products Data

View source: R/MODIStsp_process_QA_bits.R

MODIStsp_process_QA_bits

R Documentation

MODIStsp helper function to compute Quality Indicators from HDF bit-field layers

Description

function used to extract quality indicator from MODIS aggregated quality layers

Usage

MODIStsp_process_QA_bits(
  out_filename,
  in_source_file,
  bitN,
  out_format,
  nodata_source,
  nodata_qa_in,
  nodata_qa_out,
  compress
)

Arguments

`out_filename`	`character` file name of the output raster files containing QI values
`in_source_file`	`character` name of the file created by MODIStsp containing the data required to compute the quality indicator
`bitN`	`character` position of the bits corresponding to the quality indicator of interest (e.g., 0-1 = first two bits; 2-5: bits from 2 to 5, etc.)
`out_format`	output format (ENVI or GTiff)
`nodata_source`	`character` NoData values of the MODIS band containing data from which the bit field corresponding to the quality indicator must be extracted
`nodata_qa_in`	`character` in NoData for quality bands ("255")
`nodata_qa_out`	`character` out NoData for quality bands ("255")
`compress`	`character` compression option for GTiff files

Details

On the basis of the name of the image containing the aggregated quality information (⁠in_source_file``) and of the position of the bit fields corresponding to the QI of interest in the bitfield representation (⁠bitN“), the function extracts the correct information exploiting bitwise operators, and save the result in a new raster image