[R-sig-Geo] Bearing angle of UTM projected SpatialLines

[Roger Bivand]

On Wed, 25 May 2016, Eduardo Diez wrote:

> Dear everyone,
> I'm used to calculating the compass angles (clockwise from due North) of
> line features projected in UTM using the tool Linear Directional Mean
> <http://resources.esri.com/help/9.3/arcgisengine/java/gp_toolref/spatial_statistics_tools/how_linear_directional_mean_spatial_statistics_works.htm>
> from ArcGIS.
> I could find functions for performing a similar task but taking Origin ->
> Destination points and only in Lat/Lon (geographic coordinates) namely:
> geosphere::bearing and maptools::gzAzimuth. (Somehow they give different
> results for the same set of points: around 0.05 degrees, maybe because of
> the trigonometry)
> Because of the nature of my work it has to be in UTM.

Interesting question. Could you please provide a test set of pairs of 
coordinates with the fully qualified UTM projection (which datum in 
particular, and if WGS84, which version - there are several), the output 
from ArcGIS (which version), and the geographical coordinates you see in 
ArcGIS (to remove the possibility that it is a projection issue on the R 
side). They don't need to mean anything, only that they can show us what 
the problem is in code and numeric terms. A link to an R file and an RDS 
file would be helpful.

Roger

> Perhaps someone skillfull in trigonometry can figure it out but i'm not the
> case.
> Is there a way to do this in R?
>
> Thanks,
> Eduardo
>
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>
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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
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e-mail: Roger.Bivand at nhh.no
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