Last chance! 50% off unlimited learning
Sale ends in
The spTransform methods provide transformation between datum(s) and conversion between projections (also known as projection and/or re-projection), from one unambiguously specified coordinate reference system to another, using PROJ.4 projection arguments. For simple projection, when no +datum tags are used, datum projection does not occur. When datum transformation is required, the +datum tag should be present with a valid value both in the CRS of the object to be transformed, and in the target CRS. In general +datum= is to be prefered to +ellps=, because the datum always fixes the ellipsoid, but the ellipsoid never fixes the datum.
In addition, the +towgs84 tag should be used where needed to make sure that datum transformation does take place. Parameters for +towgs84 will be taken from the bundled EPSG database if they are known unequivocally, but may be entered manually from known authorities. Not providing the appropriate +datum and +towgs84 tags may lead to coordinates being out by hundreds of metres. Unfortunately, there is no easy way to provide this information: the user has to know the correct metadata for the data being used, even if this can be hard to discover.
default void method
returns transformed coordinates of an "SpatialPoints" object using the projection arguments in "CRSobj", of class CRS
returns transformed coordinates of an "SpatialPointsDataFrame" object using the projection arguments in "CRSobj", of class CRS
returns transformed coordinates of an "SpatialLines" object using the projection arguments in "CRSobj", of class CRS
returns transformed coordinates of an "SpatialLinesDataFrame" object using the projection arguments in "CRSobj", of class CRS
returns transformed coordinates of an "SpatialPolygons" object using the projection arguments in "CRSobj", of class CRS
returns transformed coordinates of an "SpatialPolygonsDataFrame" object using the projection arguments in "CRSobj", of class CRS
Because regular grids will usually not be regular after projection/datum transformation, the input object is coerced to a SpatialPointsDataFrame, and the transformation carried out on that object. A warning: “Grid warping not available, coercing to points” is given.
Because regular grids will usually not be regular after projection/datum transformation, the input object is coerced to a SpatialPointsDataFrame, and the transformation carried out on that object. A warning: “Grid warping not available, coercing to points” is given.
# NOT RUN {
data(state)
states <- data.frame(state.x77, state.center)
states <- states[states$x > -121,]
coordinates(states) <- c("x", "y")
proj4string(states) <- CRS("+proj=longlat +ellps=clrk66")
summary(states)
state.ll83 <- spTransform(states, CRS("+proj=longlat +ellps=GRS80"))
summary(state.ll83)
state.merc <- spTransform(states, CRS=CRS("+proj=merc +ellps=GRS80"))
summary(state.merc)
state.merc <- spTransform(states,
CRS=CRS("+proj=merc +ellps=GRS80 +units=us-mi"))
summary(state.merc)
if (projNAD()) {
states <- data.frame(state.x77, state.center)
states <- states[states$x > -121,]
coordinates(states) <- c("x", "y")
proj4string(states) <- CRS("+init=epsg:4267")
print(summary(states))
state.ll83 <- spTransform(states, CRS("+init=epsg:4269"))
print(summary(state.ll83))
state.kansasSlcc <- spTransform(states, CRS=CRS("+init=epsg:26978"))
print(summary(state.kansasSlcc))
SFpoint_NAD83 <- SpatialPoints(matrix(c(-103.869667, 44.461676), nrow=1),
proj4string=CRS("+init=epsg:4269"))
SFpoint_NAD27 <- spTransform(SFpoint_NAD83, CRS("+init=epsg:4267"))
print(all.equal(coordinates(SFpoint_NAD83), coordinates(SFpoint_NAD27)))
print(coordinates(SFpoint_NAD27), digits=12)
print(coordinates(SFpoint_NAD83), digits=12)
}
data(meuse)
coordinates(meuse) <- c("x", "y")
proj4string(meuse) <- CRS(paste("+init=epsg:28992",
"+towgs84=565.237,50.0087,465.658,-0.406857,0.350733,-1.87035,4.0812"))
# see http://trac.osgeo.org/gdal/ticket/1987
summary(meuse)
meuse.utm <- spTransform(meuse, CRS("+proj=utm +zone=32 +datum=WGS84"))
summary(meuse.utm)
cbind(coordinates(meuse), coordinates(meuse.utm))
kiritimati_primary_roads <- readOGR(system.file("vectors",
package = "rgdal")[1], "kiritimati_primary_roads")
kiritimati_primary_roads_ll <- spTransform(kiritimati_primary_roads,
CRS("+proj=longlat +datum=WGS84"))
opar <- par(mfrow=c(1,2))
plot(kiritimati_primary_roads, axes=TRUE)
plot(kiritimati_primary_roads_ll, axes=TRUE, las=1)
par(opar)
opar <- par(mfrow=c(1,2))
scot_BNG <- readOGR(system.file("vectors", package = "rgdal")[1],
"scot_BNG")
scot_LL <- spTransform(scot_BNG, CRS("+proj=longlat +datum=WGS84"))
plot(scot_LL, axes=TRUE)
grd_LL <- gridlines(scot_LL, ndiscr=100)
summary(grd_LL)
grd_BNG <- spTransform(grd_LL, CRS(proj4string(scot_BNG)))
grdtxt_LL <- gridat(scot_LL)
grdtxt_BNG <- spTransform(grdtxt_LL, CRS(proj4string(scot_BNG)))
plot(scot_BNG, axes=TRUE, las=1)
plot(grd_BNG, add=TRUE, lty=2)
text(coordinates(grdtxt_BNG),
labels=parse(text=as.character(grdtxt_BNG$labels)))
par(opar)
crds <- matrix(data=c(9.05, 48.52), ncol=2)
spPoint <- SpatialPoints(coords=crds,
proj4string=CRS("+proj=longlat +ellps=sphere +no_defs"))
a <- spTransform(spPoint, CRS(paste("+proj=ob_tran +o_proj=longlat",
"+o_lon_p=-162 +o_lat_p=39.25 +lon_0=180 +ellps=sphere +no_defs")),
use_ob_tran=TRUE)
a
#should be (-5.917698, -1.87195)
spTransform(a, CRS("+proj=longlat +ellps=sphere +no_defs"),
use_ob_tran=TRUE)
try(spTransform(a, CRS(paste("+proj=tmerc +lat_0=0 +lon_0=9 +k=1",
"+x_0=3500000 +y_0=0 +ellps=bessel +units=m +no_defs")),
use_ob_tran=TRUE))
spTransform(spPoint, CRS(paste("+proj=tmerc +lat_0=0 +lon_0=9 +k=1",
"+x_0=3500000 +y_0=0 +ellps=bessel +units=m +no_defs")))
spTransform(spTransform(a, CRS("+proj=longlat +ellps=sphere +no_defs"),
use_ob_tran=TRUE), CRS(paste("+proj=tmerc +lat_0=0 +lon_0=9 +k=1",
"+x_0=3500000 +y_0=0 +ellps=bessel +units=m +no_defs")))
crds1 <- matrix(data=c(7, 51, 8, 52, 9, 52, 10, 51, 7, 51), ncol=2,
byrow=TRUE, dimnames=list(NULL, c("lon", "lat")));
crds2 <- matrix(data=c(8, 48, 9, 49, 11, 49, 9, 48, 8, 48), ncol=2,
byrow=TRUE, dimnames=list(NULL, c("lon", "lat")));
crds3 <- matrix(data=c(6, 47, 6, 55, 15, 55, 15, 47, 6, 47), ncol=2,
byrow=TRUE, dimnames=list(NULL, c("lon", "lat")));
spLines <- SpatialLines(list(Lines(list(Line(crds1), Line(crds2),
Line(crds3)), ID="a")));
spLines@proj4string <- CRS("+proj=longlat +ellps=sphere +no_defs");
bbox(spLines);
spLines_tr <- spTransform(spLines, CRS("+proj=ob_tran +o_proj=longlat
+o_lon_p=-162 +o_lat_p=39.25 +lon_0=180 +ellps=sphere +no_defs"),
use_ob_tran=TRUE);
bbox(spLines_tr)
bbox(spTransform(spLines_tr, CRS("+proj=longlat +ellps=sphere"),
use_ob_tran=TRUE))
spPolygons <- SpatialPolygons(list(Polygons(list(Polygon(crds1),
Polygon(crds2), Polygon(crds3)), ID="a")));
spPolygons@proj4string <- CRS("+proj=longlat +ellps=sphere +no_defs");
bbox(spPolygons);
spPolygons_tr <- spTransform(spPolygons, CRS("+proj=ob_tran +o_proj=longlat
+o_lon_p=-162 +o_lat_p=39.25 +lon_0=180 +ellps=sphere +no_defs"),
use_ob_tran=TRUE);
bbox(spPolygons_tr)
bbox(spTransform(spPolygons_tr, CRS("+proj=longlat +ellps=sphere"),
use_ob_tran=TRUE))
#added after posting by Martin Ivanov
data(nor2k)
summary(nor2k)
nor2kNGO <- spTransform(nor2k, CRS("+init=epsg:4273"))
summary(nor2kNGO)
all.equal(coordinates(nor2k)[,3], coordinates(nor2kNGO)[,3])
#added after posting by Don MacQueen
crds <- cbind(c(-121.524764291826, -121.523480804667), c(37.6600366036405, 37.6543604613483))
ref <- cbind(c(1703671.30566227, 1704020.20113366), c(424014.398045834, 421943.708664294))
crs.step1.cf <- CRS(paste("+proj=lcc +lat_1=38.43333333333333",
"+lat_2=37.06666666666667 +lat_0=36.5 +lon_0=-120.5",
"+x_0=2000000.0 +y_0=500000.0 +ellps=GRS80 +units=us-ft +no_defs",
"+towgs84=-0.991,1.9072,0.5129,0.025789908,0.0096501,0.0116599,0.0"))
locs.step1.cf <- spTransform(SpatialPoints(crds,
proj4string=CRS("+proj=longlat +datum=WGS84")), crs.step1.cf)
suppressWarnings(proj4string(locs.step1.cf) <- CRS(paste("+proj=lcc",
"+lat_1=38.43333333333333 +lat_2=37.06666666666667 +lat_0=36.5",
"+lon_0=-120.5 +x_0=2000000.0 +y_0=500000.0 +ellps=GRS80 +units=us-ft",
"+no_defs +nadgrids=@null")))
locs.step2.cfb <- spTransform(locs.step1.cf, CRS("+init=epsg:26743"))
coordinates(locs.step2.cfb) - ref
all.equal(unname(coordinates(locs.step2.cfb)), ref)
# Test for UTM == TMERC (<= 4.9.2) or UTM == ETMERC (> 4.9.2)
nhh <- SpatialPointsDataFrame(matrix(c(5.304234, 60.422311), ncol=2),
proj4string=CRS("+init=epsg:4326"), data=data.frame(office="RSB"))
nhh_utm_32N_P4 <- spTransform(nhh, CRS("+init=epsg:3044"))
nhh_tmerc_P4 <- spTransform(nhh, CRS(paste("+proj=tmerc +k=0.9996",
"+lon_0=9 +x_0=500000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")))
nhh_etmerc_P4 <- spTransform(nhh, CRS(paste("+proj=etmerc +k=0.9996",
"+lon_0=9 +x_0=500000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")))
all.equal(coordinates(nhh_utm_32N_P4), coordinates(nhh_tmerc_P4),
tolerance=1e-9, scale=1)
# UTM == TMERC: PROJ4 <=4.9.2
all.equal(coordinates(nhh_utm_32N_P4), coordinates(nhh_etmerc_P4),
tolerance=1e-9, scale=1)
# UTM == ETMERC: PROJ4 > 4.9.2
unis <- SpatialPointsDataFrame(matrix(c(15.653453, 78.222504), ncol=2),
proj4string=CRS("+init=epsg:4326"), data=data.frame(office="UNIS"))
unis_utm_33N_P4 <- spTransform(unis, CRS("+init=epsg:3045"))
unis_tmerc_P4 <- spTransform(unis, CRS(paste("+proj=tmerc +k=0.9996 +lon_0=15",
"+x_0=500000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")))
unis_etmerc_P4 <- spTransform(unis, CRS(paste("+proj=etmerc +k=0.9996",
"+lon_0=15 +x_0=500000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs")))
all.equal(coordinates(unis_utm_33N_P4), coordinates(unis_tmerc_P4),
tolerance=1e-9, scale=1)
# UTM == TMERC: PROJ4 <=4.9.2
all.equal(coordinates(unis_utm_33N_P4), coordinates(unis_etmerc_P4),
tolerance=1e-9, scale=1)
# UTM == ETMERC: PROJ4 > 4.9.2
# }
Run the code above in your browser using DataLab