R: Cross Track Distance

dist2gc {geosphere} | R Documentation

## Cross Track Distance

### Description

Compute the distance of a point to a great-circle path (also referred to as the cross track distance or cross track error). The great circle is defined by `p1` and `p2`, while `p3` is the point away from the path.

### Usage

    dist2gc(p1, p2, p3, r=6378137)

### Arguments

`p1` | Start of great circle path. 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
`p2` | End of great circle path. As above
`p3` | Point away from the great cricle path. As for p2
`r` | radius of the earth; default = 6378137

### Value

A distance in units of `r` (default is meters)

The sign indicates which side of the path p3 is on. Positive means right of the course from p1 to p2, negative means left.

### Author(s)

Ed Williams and Robert Hijmans

### References

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

http://williams.best.vwh.net/ftp/avsig/avform.txt

### See Also

`dist2Line, alongTrackDistance`

### Examples

    dist2gc(c(0,0),c(90,90),c(80,80))

[Package geosphere version 1.5-5 Index]