R: Orthogonal Projection of Meridian or Parallel

merid {GEOmap} | R Documentation

## 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<jonathan.lees@unc.edu>

### 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))

[Package GEOmap version 2.4-0 Index]