r.in.ll

NAME

r.in.ll - Converts raster data referenced using latitude and longitude coordinates to a UTM-referenced map layer in GRASS raster format.
(GRASS Raster Data Import Program)

SYNOPSIS

r.in.ll
r.in.ll help
r.in.ll [-s] input=name output=name bpc=value corner=corner,lat,lon dimension=rows,cols res=latres,lonres spheroid=name

DESCRIPTION

This program converts raster data referenced using latitude and longitude coordinates to a UTM-referenced map layer in GRASS raster format. r.in.ll is primarily used as the final program in converting DTED and DEM digital elevation data to GRASS raster format, but is not limited to this use. r.in.ll uses the user's current geographic region settings. Only data that falls within the current geographic region will appear in the final raster map layer.

OPTIONS

r.in.ll requires the user to enter the following information:

Flags:

-s: Signed data (high bit means negative value).

Parameters:

input=name

Name of an existing input raster map layer.

output=name

Name to be assigned to the output raster map layer.

bpc=value

Number of bytes per cell.

corner=corner,lat,lon

One corner latitude and longitude of the input.
Format: {nw|ne|sw|se},dd:mm:ss{N|S},ddd:mm:ss{E|W}

The latitude and longitude are specified as dd.mm.ssH where dd is degrees, mm is minutes, ss is seconds, and H is the hemisphere (N or S for latitudes, E or W for longitudes).

For example, to specify the southwest corner: corner=sw,46N,120W

Note: the latitude and longitude specified are for the center of the corner cell.

dimension=rows,cols

Number of rows and columns in the input file.

res=latres,lonres

Resolution of the input (in arc seconds).

spheroid=name

Name of spheroid to be used for coordinate conversion.
Options: airy, australian, bessel, clark66, everest, grs80, hayford, international, krasovsky, wgs66, wgs72, wgs84

EXAMPLE

The command line:

r.in.ll input=rot.out output=import.out dimension=358,301 bpc=2 res=3,3 corner=sw,37:13N,103:45W spheroid=wgs72

reads data from the file rot.out, converts the data, and stores them in the file import.out. The data to be converted are made up of 358 rows and 301 columns, and have a resolution of 3x3 arc seconds.

NOTES

In the conversion of DTED and DEM elevation data to raster map layer format, r.in.ll follows execution of the data rotation program m.rot90. Because the user can glean information on the number of rows and columns, the resolutions of the latitude and longitude, and the number of bytes per column from the header file produced by the tape extraction programs m.dted.extract and m.dmaUSGSread, the user should recall that m.rot90 has rotated the files produced by the tape extraction programs 90 degrees; this means that the user should INTERCHANGE the numbers of rows and columns present in the header file for input to r.in.ll. The number of rows shown in the tape extract header file now become the number of columns in the m.rot90 output file; the number of columns shown in the tape extract header file are now the number of rows present in the m.rot90 output file.

The user should also note that the raster map layer imported into GRASS will be based on the current geographic region settings. The boundaries of this geographic region should therefore be checked before importing the raster map layer. Data outside of the geographic region will not be imported and missing data will be assigned the category value "no data".

AUTHOR

Michael Shapiro, U.S. Army Construction Engineering Research Laboratory