This is also possible with rgeos library(sp) library(rgeos)
x <- 673593.21 y <- 673593.21 sp0 <- SpatialPoints(coords = data.frame(x=x, y=y), proj4string = CRS('+proj=utm +zone=20 +south +ellps=WGS84 +datum=WGS84 +units=m +no_defs')) sp1 <- gBuffer(sp0, byid=TRUE, width = 15, quadsegs = 2) plot(sp1) Cheers, Loïc On 12/09/2017 16:57, Rolf Turner wrote: > > On 13/09/17 08:48, Kátia Emidio wrote: > >> Dear all, >> My question is how to create a circular spatial polygon, with 8 arcs >> of 45 >> degrees, and radius measuring 15m. Having in the centre point the UTM >> coordinates, zone 20S. >> >> x= *673593.21* >> y= *673593.21* > > "Circular polygon" is a contradiction in terms. If a shape is a polygon > then it is *not* a circle. (Of course in real life we use polygons with > large numbers of sides to *approximate* circles. But 8 is not large!) > > You can create an octagon with the required centre and radius using > *spatstat* via: > > oct <- disc(radius=15,centre=c(673593.21,673593.21),npoly=8) > > Does that provide (at least a start on) what you want? > > cheers, > > Rolf Turner > _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo