layer.Raster: Writes raster objects to KML

In plotKML: Visualization of Spatial and Spatio-Temporal Objects in Google Earth

Description

Writes rasters to PNG images and makes a KML code (ground overlays). Works with "RasterLayer" and "RasterStack" class objects. Target attributes can be specified using aesthetics arguments (e.g. "colour").

Usage

kml_layer.Raster(obj, subfolder.name = paste(class(obj)), plot.legend = TRUE, 
     metadata = NULL, raster_name, 
     png.width = ncol(obj), png.height = nrow(obj), 
     min.png.width = 800, TimeSpan.begin, TimeSpan.end,
     layer.name, png.type, ...)

Arguments

obj	object of class "RasterLayer", "SpatialPixelsDataFrame" or "SpatialGridDataFrame"
subfolder.name	character; optional subfolder name
plot.legend	logical; specify whether a map legend should be generated automatically
metadata	(optional) specify the metadata object
raster_name	(optional) specify the output file name (PNG)
png.width	(optional) width of the PNG file
png.height	(optional) height of the PNG file
min.png.width	(optional) minimum width of the PNG file
TimeSpan.begin	object of class "POSIXct"; (optional) begin of the sampling period
TimeSpan.end	object of class "POSIXct"; (optional) end of the sampling period
layer.name	character; optional layer name
png.type	character; PNG type
...	additional aesthetics arguments

Details

Google Earth does not properly handle a 24-bit PNG file which has a single transparent color (read more at Google Earth Help). To force transparency, plotKML will try to set it using the -matte -transparent "\#FFFFFF" option in the ImageMagick convert program (ImageMagick needs to be installed separately and located using plotKML.env()). On some Unix run machines the png.type argument has to be set manually to avoid producing empty PNGs.

Author(s)

Tomislav Hengl, Pierre Roudier and Dylan Beaudette

See Also

kml-methods, kml_open, kml_layer.RasterBrick, plotKML-method

Examples

data(eberg_grid)
library(sp)
coordinates(eberg_grid) <- ~x+y
gridded(eberg_grid) <- TRUE
proj4string(eberg_grid) <- CRS("+init=epsg:31467")
data(SAGA_pal)
library(raster)
r <- raster(eberg_grid["TWISRT6"])
## Not run: # KML plot with a single raster:
kml(r, colour_scale = SAGA_pal[[1]], colour = TWISRT6) 

## End(Not run)

Example output

plotKML version 0.6-1 (2020-03-08)
URL: http://plotkml.r-forge.r-project.org/
Warning message:
In showSRID(uprojargs, format = "PROJ", multiline = "NO", prefer_proj = prefer_proj) :
  Discarded datum Deutsches_Hauptdreiecksnetz in CRS definition
KML file opened for writing...
Reprojecting to +proj=longlat +datum=WGS84 +no_defs ...
sh: 1: awk: Permission denied

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Writing to KML...
Closing  r.kml
Warning message:
In showSRID(uprojargs, format = "PROJ", multiline = "NO", prefer_proj = prefer_proj) :
  Discarded datum Unknown based on Bessel 1841 ellipsoid in CRS definition

plotKML documentation built on April 27, 2021, 3:01 p.m.