# densify: Add additional nodes to lines or polygons In terra: Spatial Data Analysis

 densify R Documentation

### 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, flat=FALSE)
``````

### Arguments

 `x` SpatVector `interval` positive number, specifying the desired minimum distance between nodes. The unit is meter for lonlat data, and in the linear unit of the crs for planar data `equalize` logical. If `TRUE`, new nodes are spread at equal intervals between old nodes `flat` logical. If `TRUE`, the earth's curvature is ignored for lonlat data, and the distance unit is degrees, not meter

SpatVector

### 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")

lines(p, col="blue", lwd=3)
points(p, col="blue", cex=2)
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")
plot(y)
# good
lines(vd, col="red")
``````

terra documentation built on Oct. 13, 2023, 5:08 p.m.