DESCRIPTION

This program outputs two or four column (with -g) data to stdout or an ASCII file. The default two column output consists of cumulative profile length (in meters) and raster value. The optional four column output consists of easting, northing, cumlative profile length (m), and raster value. Profile end or "turning" points can be set manually with the coordinates argument. The profile resolution, or distance between profile points, is obtained from the current region resolution, or can be manually set with the resolution argument.

The coordinates parameter can be set to comma separated geographic coordinates for profile line endpoints. Alternatively the coordinate pairs can be piped from the text file specified by file option, or if set to "-", from stdin. In these cases the coordinate pairs should be given one comma separated pair per line.

The resolution parameter sets the distance between each profile point (resolution). The resolution must be provided in GRASS database units (i.e. decimal degrees for Lat Long databases and meters for UTM). By default r.profile uses the resolution of the current GRASS region.

The null parameter can optionally be set to change the character string representing null values.

OUTPUT FORMAT

The multi column output from r.profile is intended for easy use in other programs. The output can be piped (|) directly into other programs or saved to a file for later use. Output with geographic coordinates (-g) is compatible with v.in.ascii and can be piped direcly into this program. 
r.profile -g input=elevation coordinates=... | v.in.ascii output=elevation_profile separator=space
The 2 column output is compatible with most plotting programs.

The optional RGB output provides the associated GRASS colour value for each profile point.

EXAMPLES

Example 1
Extract a profile with coordinates provided on the command line: 
r.profile input=elevation output=profile_points coordinates=562517,7779433,562984,7779533,563875,7779800
This will extract a profile along the track defined by the three coordinate pairs.


Example 2
Pipe coordinates into r.profile 

r.profile elevation.dem res=1000 file=- << EOF
 591243,4926344
 592509,4922156
 594100,4920793
 599910,4919365
 602929,4919235
 604844,4918391
 606468,4917190
 607766,4915664
EOF

NOTES

The profile resolution is measured exactly from the supplied end or "turning" point along the profile. The end of a profile segment will be an exact multiple of the profile resolution and will therefore not always match the end point coordinates entered for the segmanet.

To extract the numbers in scripts, following parameters can be used: 

r.profile input=dgm12.5 coordinates=3570631,5763556 2>/dev/null
This filters out the everything except the numbers.

SEE ALSO

v.in.ascii, r.what, r.transect, wxGUI profile tool

AUTHOR

Bob Covill

Last changed: $Date$