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

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

Note

License: GPL 3.0 Based on the modis.qc.R script by Yann Chemin (2008) (https://goo.gl/7Fhreo) license GPL 3.0

Author

Lorenzo Busetto, phD (2017)

Luigi Ranghetti, phD (2017)