intermediate function

Intermediate points on a great circle (sphere)

Get intermediate points (way points) between the two locations with longitude/latitude coordinates. gcIntermediate is based on a spherical model of the earth and internally uses distCosine. 1.1

gcIntermediate(p1, p2, n=50, breakAtDateLine=FALSE, addStartEnd=FALSE, sp=FALSE, sepNA)

Arguments

• p1: longitude/latitude of a single point, in degrees. This can be a vector of two numbers, a matrix of 2 columns (first one is longitude, second is latitude) or a SpatialPoints* object
• p2: as for p1
• n: integer. The desired number of intermediate points
• breakAtDateLine: logical. Return two matrices if the dateline is crossed?
• addStartEnd: logical. Add p1 and p2 to the result?
• sp: logical. Return a SpatialLines object?
• sepNA: logical. Rather than as a list, return the values as a two column matrix with lines seperated by a row of NA values? (for use in 'plot')

Returns

matrix or list with intermediate points

References

https://www.edwilliams.org/avform147.htm#Intermediate

Author(s)

Robert Hijmans based on code by Ed Williams (great circle)

Examples

gcIntermediate(c(5,52), c(-120,37), n=6, addStartEnd=TRUE)