cleanMODIS: Clean MODIS

In dutri001/bfastSpatial: Utilities to monitor for change on satellite image time-series

Description

Uses MODIS quality layer to perform cleaning over a single data layer. Quality band can be encoded bitewise or in numerics. This function needs rgdal to be configured with HDF4 driver in order to work.

Usage

cleanMODIS(x, data_SDS, QC_SDS, bit = FALSE, QC_val, fill = NULL, ...)

Arguments

x	Character. Filename (full path) of a hdf dataset containing data and QC layers
data_SDS	Numeric. Index of the SDS containing the data in the hdf infrastructure
QC_SDS	Numeric. Index of the SDS containing the Quality control in the hdf infrastructure
bit	Logical. Is QC information provided bitwise?
QC_val	Numeric or vector of numerics. Quality control values to keep in the data. If bit is set to TRUE QC_val is a BYTE (hexadecimal or decimal) where each bit refers to a bit in the QC layer element (i.e.: bitpos = 0xA1 targets bits 7, 5 and 0 — 1010 0001). When bits targetted by QC_val are activated, the corresponding observation in the data layer is filtered out.
fill	(vector of) Numeric or NULL. Fill values in the data layer to be filtered out. (important to do before reprojection with resampling method other than Nearest Neighbours)
...	Arguments to be passed to writeRaster.

Value

A rasterLayer

Author(s)

Loic Dutrieux

See Also

processMODISbatch for batcher

Examples

## Not run: 
library(raster)
dir <- file.path(tmpDir(), 'MODIStest'); dir.create(path = dir)

fileDL <- 'http://e4ftl01.cr.usgs.gov/MOLT/MOD17A2.055/2003.07.12/MOD17A2.A2003193.h19v07.055.2011269202445.hdf'
modis <- file.path(dir, basename(fileDL)); download.file(url = fileDL, destfile = modis)

# Now We've just downloaded a MODIS file that is stored in a subdirectory of the raster tmp directory
sprintf('These data have been acquired around %s', getMODISinfo(modis)$date)

# Clean dataset and replace fill values by NAs
# Product details at https://lpdaac.usgs.gov/products/modis_products_table/mod17a2
MODISclean <- cleanMODIS(x=modis, data_SDS=1, QC_SDS=3, bit=TRUE, QC_val=0x19, fill = (32761:32767))
plot(MODISclean)

# In that case we did not write the result back to disk, but note that this is possible
# For that use the filename= argument, and the datatype= argument (recommended)

## End(Not run)

dutri001/bfastSpatial documentation built on May 15, 2019, 6:05 p.m.