omerc | R Documentation |
Defines an appropriate Oblique Mercator, Oblique Cylindrical Equal Area, and Mollweide projections for a supplied Spatial object
omerc(x, angle,
post=c('none', 'north', 'wide','tall'),
preserve=NULL, ellipse=TRUE)
ocea(x, angle, flip=FALSE)
moll(x=0, angle=NULL, flip=FALSE)
x |
A |
angle |
angle of rotation or vector of angles |
post |
post-projection angle rotation |
flip |
post-projection flipping of coordinates |
preserve |
A |
ellipse |
compute projection region and areas to crop when projecting. |
With omerc
, an Oblique Mercator 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.
ocea
produces an Oblique Cylindrical Equal Area projection and moll
a Mollweide projections
An object of class crs
.
https://en.wikipedia.org/w/index.php?title=Space-oblique_Mercator_projection
crs
,
project
data('worldMap')
worldMap = terra::unwrap(worldMap)
myProj = omerc(c(-100,-70), angle=-45)
crs(myProj, proj=TRUE)
plot(project(worldMap, crsLL))
plot(attributes(myProj)$crop, col='red', add=TRUE)
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