## DESCRIPTION

m.cogo converts data points between bearing and distance and X,Y coordinates. Only simple bearing/distance or coordinate pairs are handled. It assumes a cartesian coordinate system.

Input can be entered via standard input (default) or from the file input=name. Specifying the input as "-" also specifies standard input, and is useful for using the program in a pipeline. Output will be to standard output unless a file name other than "-" is specified. The input file must closely adhere to the following format, where up to a 10 character label is allowed but not required (see -l flag).

Example COGO input:

       P23 N 23:14:12 W 340
       P24 S 04:18:56 E 230
       ...

The first column may contain a label and you must use the -l flag so the program knows. This is followed by a space, and then either the character 'N' or 'S' to indicate whether the bearing is relative to the north or south directions. After another space, the angle begins in degrees, minutes, and seconds in "DDD:MM:SS.SSSS" format. Generally, the angle can be of the form digits + separator + digits + separator + digits [+ '.' + digits]. A space follows the angle, and is then followed by either the 'E' or 'W' characters. A space separates the bearing from the distance (which should be in appropriate linear units).

Output of the above input:

       -134.140211 312.420236 P23
       -116.832837 83.072345 P24
       ...

Unless specified with the coord option, calculations begin from (0,0).

## NOTES

For those unfamiliar with the notation for bearings: Picture yourself in the center of a circle. The first hemispere notation tell you whether you should face north or south. Then you read the angle and either turn that many degrees to the east or west, depending on the second hemisphere notation. Finally, you move <distance> units in that direction to get to the next station.

m.cogo can be run either non-interactively or interactively. The program will be run non-interactively if the user specifies any parameter or flag. Use "m.cogo -", to run the program in a pipeline. Without any flags or parameters, m.cogo will prompt for each value using the familiar GRASS parser interface.

This program is very simplistic, and will not handle deviations from the input format explained above. Currently, the program doesn't do anything particularly useful with the output. However, it is envisioned that this program will be extended to provide the capability to generate vector and/or sites layers.

Lines may be closed by using the -c flag or snapped with v.clean, lines may be converted to boundaries with v.type, and closed boundaries may be converted to areas with v.centroids.

## EXAMPLES

       m.cogo -l in=cogo.dat

Where the `cogo.dat` input file looks like:

    # Sample COGO input file -- This defines an area.
    # <label> <bearing> <distance>
    P001 S 88:44:56 W 6.7195
    P002 N 33:34:15 W 2.25
    P003 N 23:23:50 W 31.4024
    P004 N 05:04:45 W 25.6981
    P005 N 18:07:25 E 22.2439
    P006 N 27:49:50 E 75.7317
    P007 N 22:56:50 E 87.4482
    P008 N 37:45:15 E 37.7835
    P009 N 46:04:30 E 11.5854
    P010 N 90:00:00 E 8.8201
    P011 N 90:00:00 E 164.1128
    P012 S 48:41:12 E 10.1311
    P013 S 00:25:50 W 255.7652
    P014 N 88:03:13 W 98.8567
    P015 S 88:44:56 W 146.2713
    P016 S 88:44:56 W 18.7164

Round trip:

       m.cogo -l input=cogo.dat | m.cogo -rl in="-"

Import as a vector points map:

       m.cogo -l input=cogo.dat | v.in.ascii output=cogo_points x=1 y=2 separator=space

Shell script to import as a vector line map:

       m.cogo -l input=cogo.dat | tac | awk '
           BEGIN { FS=" " ; R=0 }
           $1~/\d*\.\d*/ { printf(" %.8f %.8f\n", $1, $2) ; ++R }
           END { printf("L %d\n", R) }' | tac | \
           v.in.ascii -n format=standard out=cogo_line

Convert that lines map into an area:

       # Add the -c flag to the above example to close the loop:
       m.cogo -l -c input=cogo.dat | ...
           ...
       v.type input=cogo_line output=cogo_boundary from_type=line to_type=boundary
       v.centroids input=cogo_boundary output=cogo_area

If necessary, snap the boundary closed with the v.clean module. Use `tool=snap` and `thresh=0.0001`, or some small value.

## SEE ALSO

v.centroids, v.clean, wxGUI vector digitizer, v.in.ascii, v.type

## AUTHOR

Eric G. Miller