| mapTissot {oce} | R Documentation |
Plot ellipses at grid intersection points, as a method for indicating the distortion inherent in the projection, somewhat analogous to the scheme used in reference 1. (Each ellipse is drawn with 64 segments.)
mapTissot(grid = rep(15, 2), scale = 0.2, crosshairs = FALSE, ...)
grid |
numeric vector of length 2, specifying the increment in
longitude and latitude for the grid. Indicatrices are drawn at e.g.
longitudes |
scale |
numerical scale factor for ellipses. This is multiplied by
|
crosshairs |
logical value indicating whether to draw constant-latitude
and constant-longitude crosshairs within the ellipses. (These are drawn
with 10 line segments each.) This can be helpful in cases where it is
not desired to use |
... |
extra arguments passed to plotting functions, e.g.
|
Dan Kelley
Snyder, John P., 1987. Map Projections: A Working Manual. USGS Professional Paper: 1395 (available at https://pubs.er.usgs.gov/publication/pp1395).
A map must first have been created with mapPlot().
Other functions related to maps:
formatPosition(),
lonlat2map(),
lonlat2utm(),
map2lonlat(),
mapArrows(),
mapAxis(),
mapContour(),
mapCoordinateSystem(),
mapDirectionField(),
mapGrid(),
mapImage(),
mapLines(),
mapLocator(),
mapLongitudeLatitudeXY(),
mapPlot(),
mapPoints(),
mapPolygon(),
mapScalebar(),
mapText(),
oceCRS(),
shiftLongitude(),
usrLonLat(),
utm2lonlat()
library(oce) data(coastlineWorld) par(mfrow=c(1, 1), mar=c(2, 2, 1, 1)) p <- "+proj=aea +lat_1=10 +lat_2=60 +lon_0=-45" mapPlot(coastlineWorld, projection=p, col="gray", longitudelim=c(-90,0), latitudelim=c(0, 50)) mapTissot(c(15, 15), col='red')