write_MRTSwath_param_file: Write a parameter control file for MRTSwath
In modiscloud: R tools for processing Level 2 Cloud Mask products from MODIS

Description Usage Arguments Details Value Author(s) References See Also Examples

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

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

`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

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.

prmfn The name of the temporary parameter file

Nicholas J. Matzke matzke@berkeley.edu

NASA (2001). "MODLAND Product Filename Convention." <URL: http://landweb.nascom.nasa.gov/cgi-bin/QA_WWW/newPage.cgi?fileName=hdf_filename>.

run_swath2grid

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

# 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)