mapmisc (version 1.2.1)

omerc: Oblique mercator projections

Description

Defines an appropriate oblique mercator projection for a spatial object

Usage

omerc(x, angle,  
	post=c('none', 'north', 'wide','tall'),
    preserve=NULL)

Arguments

x

A SpatialP* object or a vector of length 2 giving the centroid of the projection.

angle

angle of rotation or vector of angles

post

post-projection angle rotation

preserve

A SpatialPoints object, the resulting projection is scaled so as to preserve the distances between these points as best as possible.

Value

• An object of class CRS.

Details

A map projection is produced which warps the world onto a cylinder, with the north-south axis rotated by the specified angle. If angle is a vector, the optimal angle for reducing the size of the bounding box is returned.

If post = 'north', an inverse rotation will preserve the north direction at the origin.

If post = 'wide', an inverse rotation makes the smallest possible bounding box which is wider than tall.

If post = 'tall', the bounding box is taller than it is wide

If post is numeric, it specifies an angle for inverse rotation.

References

http://www.remotesensing.org/geotiff/proj_list/oblique_mercator.html, http://en.wikipedia.org/wiki/Space-oblique_Mercator_projection

See Also

CRS,spTransform

Examples

omerc(c(10,50), angle=c(0,45,80))

data('netherlands')

if(require('rgdal', quietly=TRUE)){
nldUtm = spTransform(nldCities,
	omerc(nldCities, angle=0))
projection(nldUtm)

map.new(nldUtm)
text(nldUtm,labels=nldUtm$name)
scaleBar(nldUtm, 'topright')

nldRot = spTransform(nldCities,
omerc(nldCities, angle=seq(25,45,by=1))
)
projection(nldRot)

map.new(nldRot)
text(nldRot,labels=nldRot$name)
scaleBar(nldRot, 'topright')
insetMap(nldRot, 'bottomright',map=world)
}
map.new(nldCities)
	plot(nldTiles,add=TRUE)
	text(nldCities,labels=nldCities$name)

	tilesRot = openmap(nldRot)
	map.new(nldRot)
	plot(tilesRot,add=TRUE)
	text(nldRot,labels=nldRot$name)
	
	tilesUtm = openmap(nldUtm)
	map.new(nldUtm)
	plot(tilesUtm,add=TRUE)
	text(nldUtm,labels=nldUtm$name)