densify {terra}

R Documentation

Add additional nodes to lines or polygons

Description

Add additional nodes to lines or polygons. This can be useful to do prior to using project such that the path does not change too much.

Usage

## S4 method for signature 'SpatVector'
densify(x, interval, equalize=TRUE)

Arguments

x	SpatVector
interval	numeric larger than 1, specifying the desired minimum interval between nodes
equalize	logical. If TRUE, new nodes are spread at equal intervals between old nodes

Value

SpatVector

Examples

Run examples

v <- vect(rbind(c(-120,-20), c(-80,5), c(-40,-60), c(-120,-20)), 
  type="polygons", crs="+proj=longlat")
vd <- densify(v, 200000)

p <- project(v, "+proj=robin")
pd <- project(vd, "+proj=robin")

# good 
plot(pd, col="gray", border="red", lwd=10)
points(pd, col="gray")

# bad
lines(p, col="blue", lwd=3)
points(p, col="blue", cex=2)
plot(p, col="blue", alpha=.1, add=TRUE)
legend("topright", c("good", "bad"), col=c("red", "blue"), lty=1, lwd=3)

## the other way around does not work
## unless the original data was truly planar (e.g. derived from a map)
x <- densify(p, 250000)
y <- project(x, "+proj=longlat")
# bad
plot(y)
# good
lines(vd, col="red")

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