rgl.sphline: Draw Great and Minor Circle Line Segments

In asgr/sphereplot: Spherical Plotting

Draw Great and Minor Circle Line Segments

Description

Given points on a sphere, these functions will draw the connecting great and minor circle minimum distance line connecting them.

Usage

rgl.sphline(long1, lat1, long2, lat2, radius = 1, deg = TRUE, col = "black", res = 1000,
  ...)
rgl.sphlines(long, lat, ...)
rgl.seglong(long1, long2, lat, radius=1, deg=TRUE, col='black', res=1000, ...)
rgl.seglat(long, lat1, lat2, radius=1, deg=TRUE, col='black', res=1000, ...)
rgl.segbox(long1, long2, lat1, lat2, radius=1, deg=TRUE, col='black', res=1000, ...)

Arguments

long1	Numeric scalar; longitude of first location.
lat1	Numeric scalar; latitude of first location.
long2	Numeric scalar; longitude of second location.
lat2	Numeric scalar; latitude of second location.
long	Numeric vector; longitudes on plotting path.
lat	Numeric vector; latitudes on plotting path.
radius	Numeric scalar; radius of segment to draw.
deg	Logical; specifies if input is in degrees (default) or radians.
col	Specifies line colour.
res	Numeric scalar; resolution of line to draw (how many elements in the total great circle). Only make this large if plotting points very close together, otherwise the default is generally high enough resolution.
...	Other arguments to pass to lines3d.

Details

The main difference between rgl.sphline and rgl.sphlines is that the former takes scalar inputs but gives you the great outputs listed below, whilst rgl.sphlines can take vector inputs and plot complicated paths, but provides no return from the function.

Value

rgl.sphline and rgl.sphlines are called for the side effect of plotting on the current sphere.

rgl.seglong draws longitude lines of constant latitude (technically minor circle arcs, except at the equator).

rgl.seglat draws latitude lines of constant longitude (great circle arcs).

rgl.segbox draws boxes with the specified longitude and latitude limits.

rgl.sphline also returns various diagnostic outputs:

great_circle	Cartesian coordinates of the full great circle.
segment	Cartesian coordinates of the great circlen segment.
CrossEq	Location where great circle crosses the equator.
PeakDec	Peak declination / latitude of the great circle.
AngSep	Angular separation of the two points in degrees.
CrossProd	Three element cross product vector for the two input positions.

Author(s)

Aaron Robotham

See Also

rgl.sphglobe

Examples

rgl.sphglobe('world1')
rgl.sphline(20,30,40,60)
rgl.sphpoints(c(20,40), c(30,60), size=10)
rgl.sphline(340,-20,80,30)
rgl.sphpoints(c(340,80), c(-20,30), size=10)
rgl.sphline(30,40,80,-60)
rgl.sphpoints(c(30,80), c(40,-60), size=10)

asgr/sphereplot documentation built on Sept. 5, 2023, 4:58 a.m.