R: Intersections of two great circles

gcIntersectBearing {geosphere} | R Documentation

## Intersections of two great circles

### Description

Get the two points where two great cricles cross each other. In this function, great circles are defined by a points and an initial bearing. In function `gcIntersect` they are defined by two sets of points.

### Usage

    gcIntersectBearing(p1, brng1, p2, brng2)

### Arguments

`p1` | longitude/latitude of point(s). Can be a vector of two numbers, a matrix of 2 columns (first one is longitude, second is latitude) or a SpatialPoints* object
`brng1` | Bearing from p1
`p2` | As above. Should have same length as p1, or a single point (or vice versa when p1 is a single point
`brng2` | Bearing from p2

### Value

a matrix with four columns (two points)

### Author(s)

Chris Veness and Robert Hijmans based on code by Ed Williams

### References

http://williams.best.vwh.net/avform.htm#Intersection

http://www.movable-type.co.uk/scripts/latlong.html

### See Also

`gcIntersect`

### Examples

    gcIntersectBearing(c(10,0), 10, c(-10,0), 10)

[Package geosphere version 1.5-5 Index]