[GRASS-user] V.distance - to_angle

Richard Chirgwin rchirgwin at ozemail.com.au
Sat Mar 13 00:31:17 EST 2010


Trying to capture directions in v.distance.

The manual says that to_angle is measured:
"Counterclockwise from positive x axis, in radians, which is between -PI 
and PI inclusive."

But: I'm getting a value of 0.83 for something which on a compass would 
be about 170 degrees from North.

If I assume that a line in this direction is  -Pi   ---->
...then I would expect that as we rotate to here <-----
...we approach 0

So I would expect something pointing nearly south to be a value of about 
1/2 Pi - not 0.8, anyhow.

Or have I misread the manual?


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