[GRASS5] [bug #3145] (grass) R.profile does not use great circle paths

Request Tracker grass-bugs at intevation.de
Tue Apr 5 14:46:40 EDT 2005

this bug's URL: http://intevation.de/rt/webrt?serial_num=3145

Subject: R.profile does not use great circle paths

Platform: GNU/Linux/i386
grass obtained from: Other (CDROM etc)
grass binary for platform: Downloaded precompiled Binaries

The r.profile command takes profiles along straight lines which is not correct if the surface the profile is being taken over is the projection of the earth's surface. In this case great circle paths should be taken.
The simplest fix is to update the man page so it is clear that the angle between the starting and endpoints as if they were on a flat plane is used to calculate the intermediate points (At least this is what it looks like from the quick glance at the source code I took after I didn't understand the results I was getting). If a great circle was used then this azimuthal angle/bearing would change as you move along the path.

Hope this helps

Glyn Edwards

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