An R function to convert kml files saved from Google Earth to data frames of utm and long-lat coordinates.
The default UTM zone is 50, and the default hemisphere is South
(EPSG:32750). These defaults can be changed by specifying different
values for the utmzone= and hemi=
parameters.
The code uses the WGS84 ellipsoid for Longitude-Latitude
coordinates, but this can be changed by editing the function code before
running to include the edited kmlconvert() function in the
R global environment.
Note: depending on the type of kml file, the output is:
kmlconvert <- function(file = NULL, utmzone = 50, hemi = "south") {
require(sf)
require(maptools)
LongLat <- st_crs(4326)
UTM <- st_crs(paste0("+proj=utm +zone=",utmzone," +",hemi))
kml_0 <- getKMLcoordinates(file, ignoreAltitude = T)
if(is.matrix(kml_0[[1]])){
coords_0 <- as.data.frame(matrix(unlist(kml_0), length(unlist(kml_0))/2, 2))
colnames(coords_0) <- c("x","y")
LL_0 <- st_as_sf(coords_0, coords=c("x","y"), crs = LongLat)
utm_0 <- st_transform(LL_0, crs = UTM)
rslt_0 <- as.data.frame(cbind(st_coordinates(LL_0), st_coordinates(utm_0)))
colnames(rslt_0) <- c("Longitude", "Latitude", "Easting", "Northing")
cat("Path, line, or polygon\n")
print(rslt_0, digits=8, row.names=F)
write.table(rslt_0, file="clipboard", row.names = F, sep="\t")
cat("\nOutput data also copied to clipboard\n")
} else {
coords_0 <- as.data.frame(matrix(unlist(kml_0), length(kml_0), 2, byrow=T))
colnames(coords_0) <- c("x","y")
LL_0 <- st_as_sf(coords_0, coords=c("x","y"), crs = LongLat)
utm_0 <- st_transform(LL_0, crs = UTM)
rslt_0 <- as.data.frame(cbind(st_coordinates(LL_0), st_coordinates(utm_0)))
colnames(rslt_0) <- c("Longitude", "Latitude", "Easting", "Northing")
cat("Individual points\n")
print(rslt_0, digits=8, row.names=F)
write.table(rslt_0, file="clipboard", row.names = F, sep="\t")
cat("\nOutput data also copied to clipboard\n")
}
return(rslt_0)
rm(list = ls(pattern = "_0"))
}We can test the function on a kml file saved from Google Earth:
kml1 <- "https://github.com/Ratey-AtUWA/spatial/raw/main/botanic.kml"
cat("first 10 lines of input file:\n\n")
readLines(kml1)[1:10] ; cat(" \u22EE\n\n",rep("-",60),"\n",sep="")
kmlconvert(kml1, 50, "south")## Loading required package: maptools## Checking rgeos availability: FALSE
## Please note that 'maptools' will be retired during 2023,
## plan transition at your earliest convenience;
## some functionality will be moved to 'sp'.
## Note: when rgeos is not available, polygon geometry computations in maptools depend on gpclib,
## which has a restricted licence. It is disabled by default;
## to enable gpclib, type gpclibPermit()##
## Attaching package: 'maptools'## The following objects are masked from 'package:sp':
##
## elide, sp2Mondrian## first 10 lines of input file:
##
## [1] "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
## [2] "<kml xmlns=\"http://www.opengis.net/kml/2.2\" xmlns:gx=\"http://www.google.com/kml/ext/2.2\" xmlns:kml=\"http://www.opengis.net/kml/2.2\" xmlns:atom=\"http://www.w3.org/2005/Atom\">"
## [3] "<Document>"
## [4] "\t<name>botanic.kml</name>"
## [5] "\t<StyleMap id=\"msn_open-diamond\">"
## [6] "\t\t<Pair>"
## [7] "\t\t\t<key>normal</key>"
## [8] "\t\t\t<styleUrl>#sn_open-diamond</styleUrl>"
## [9] "\t\t</Pair>"
## [10] "\t\t<Pair>"
## ⋮
##
## ------------------------------------------------------------
## Individual points
## Longitude Latitude Easting Northing
## 115.81952 -31.983884 388474 6460742
## 115.81949 -31.983902 388472 6460740
## 115.81961 -31.983966 388483 6460733
## 115.81964 -31.983931 388486 6460737
## 115.81959 -31.983894 388481 6460741
##
## Output data also copied to clipboard
## Longitude Latitude Easting Northing
## 1 115.8195 -31.98388 388474 6460742
## 2 115.8195 -31.98390 388472 6460740
## 3 115.8196 -31.98397 388483 6460733
## 4 115.8196 -31.98393 388486 6460737
## 5 115.8196 -31.98389 388481 6460741CC-BY-SA • All content by Ratey-AtUWA. My employer does not necessarily know about or endorse the content of this website.
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