[GRASS-dev] m.cogo enhancement suggestion

Garth Fletcher garth at jacqcad.com
Sat Jan 20 19:21:22 PST 2018

m.cogo converts  sequences of bearing,distance pairs into coordinates

The bearing entry is in the form "N 52:17:04 W" widely used in survey maps.

However, many surveys use magnetic bearings which are rotated from
true geographic North by an angle called the Declination - which itself
depends on the date and location.

When working with such data it is first necessary to convert the
magnetic bearing by adding(subtracting) the Declination as known
for the date and location of the survey.

This is tedious when a survey could consist of hundreds of bearings,
especially when adding a 15° declination "wraps around" a bearing, for 
example, from N 10 E to N 5 W.

It would be very helpful if one could provide a Declination argument
to m.cogo which would be added to each bearing.  All that is needed
in processing is to add the Declination value to the Azimuth and
handle the special cases of result <0 or >= 360.

Way above my skill level, but I'm hoping somebody might take an interest.

Garth Fletcher

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