modiscloud (version 0.14)

write_MRTSwath_param_file: Write a parameter control file for MRTSwath

Description

MRTSwath is the "MODIS Reprojection Tool for swath products". See: https://lpdaac.usgs.gov/tools/modis_reprojection_tool_swath).

Usage

write_MRTSwath_param_file(prmfn = "tmpMRTparams.prm", tifsdir, modfn, geoloc_fn, ul_lon, ul_lat, lr_lon, lr_lat)

Arguments

prmfn

The name of the parameter/control file which will be the input to MRTSwath's swath2grid function.

tifsdir

The directory to save the output TIF files in

modfn

The filename of the MODIS data

geoloc_fn

The filename of the corresponding geolocation file (annoyingly, this is a much larger file than the data file!)

ul_lon

Upper left (ul) longitude (x-coordinate) for subsetting

ul_lat

Upper left (ul) latitude (y-coordinate) for subsetting

lr_lon

Lower right (lr) longitude (x-coordinate) for subsetting

lr_lat

Lower right (lr) latitude (y-coordinate) for subsetting

Value

prmfn The name of the temporary parameter file

Details

If you want this function to use MRTSwath tool successfully, you should add the directory with the MRTSwath executable to the default R PATH by editing ~/.Rprofile.

This function hard-codes these options into the parameter file: * all the bands are extracted * the output file is a GeoTIFF * the output projection is Geographic (plain unprojected Latitude/Longitude) * the resampling is Nearest Neighbor (NN), which of course is the only one which makes sense when the pixels encode bytes that encode bits that encode discrete classification results, 0/1 error flags, etc.

MRTswath can do many other projections and output formats; users can modify this function to run those options.

References

NASA (2001). "MODLAND Product Filename Convention." .

See Also

run_swath2grid

http://landweb.nascom.nasa.gov/cgi-bin/QA_WWW/newPage.cgi?fileName=hdf_filename

Examples

# Source MODIS files (both data and geolocation)
# Code excluded from CRAN check because it depends on modiscdata
## Not run: 
# library(devtools)
# # The modiscdata (MODIS c=cloud data=data) package is too big for CRAN (60 MB); so it is available on github:
# # https://github.com/nmatzke/modiscdata
# # If we can't get install_github() to work, try install_url():
# # install_github(repo="modiscdata", username="nnmatzke")
# install_url(url="https://github.com/nmatzke/modiscdata/archive/master.zip")
# library(modiscdata)
# moddir = system.file("extdata/2002raw/", package="modiscdata")
# 
# # Get the matching data/geolocation file pairs
# fns_df = check_for_matching_geolocation_files(moddir, modtxt="MYD35_L2", geoloctxt="MYD03")
# fns_df
# 
# # Resulting TIF files go in this directory
# tifsdir = getwd()
# 
# 
# # Box to subset
# ul_lat = 13
# ul_lon = -87
# lr_lat = 8
# lr_lon = -82
# 
# for (i in 1:nrow(fns_df))
# 	{
# 
# 	prmfn = write_MRTSwath_param_file(prmfn="tmpMRTparams.prm", tifsdir=tifsdir, modfn=fns_df$mod35_L2_fns[i], geoloc_fn=fns_df$mod03_fns[i], ul_lon=ul_lon, ul_lat=ul_lat, lr_lon=lr_lon, lr_lat=lr_lat)
# 	print(scan(file=prmfn, what="character", sep="\n"))
# 
# 	}
# ## End(Not run)