merid {GEOmap}

Orthogonal Projection of Meridian or Parallel

Description

Orthogonal Projection Meridian or Parallel

Usage

merid(lon, lat1=-90,   lat2=90,  lam0=0, phi1=41, R=1, by=1)
paral(lat, lon1=-180 , lon2=180, lam0=0, phi1=41, R=1, by=1)

Arguments

lon

merid starting Longitude, degrees

lat

paral starting Latitude, degrees

lam0

origin Longitude, degrees

phi1

origin Latitude, degrees

R

Radius

by

increment in degrees

lat1

merid starting Latitude, degrees

lat2

merid ending Latitude, degrees

lon1

paral starting Longitude, degrees

lon2

paral ending Longitude, degrees

Details

Retruns points along a meridian running through lat, lon with a projection based on lam0 phi.

Value

list of x-y values for plotting

Author(s)

Jonathan M. Lees<[e-mail]>

References

Snyder, John P., Map Projections- a working manual, USGS, Professional Paper, 1987.

See Also

ortho.proj

Examples

 olat = 0
         olon = 0

          tlat = 23
         tlon = 30

M = merid(tlon, lat1=tlat, olon, olat, 1)


R = 1

phi1=40


GLOBE.ORTH(20, phi1, 1,plotmap=FALSE)

M1 = merid(20, lat1=20, lat2=40, phi1=phi1, lam0=olat, R=1, by=1)

P2 = paral(40, lon1=20 , lon2=40, lam0=olat, phi1=phi1, R=1, by=1)

M2 = merid(40, lat1=40, lat2=20, phi1=phi1, lam0=olat, R=1, by=1)

P1 = paral(20, lon1=40 , lon2=20, lam0=olat, phi1=phi1, R=1, by=1)

polygon(c(M1$x, P2$x, M2$x, P1$x), c(M1$y, P2$y, M2$y, P1$y),
col=rgb(.8, .8, 1))