GDALinfo reports the
size and other parameters of the dataset. create2GDAL creates
a GDAL data set from a SpatialGridDataFrame object, in particular to
be able to save to GDAL driver formats that only permit copying rather
than creation.readGDAL(fname, offset, region.dim, output.dim, band, p4s=NULL, ..., half.cell=c(0.5, 0.5), silent = FALSE, OVERRIDE_PROJ_DATUM_WITH_TOWGS84=NULL)
asSGDF_GROD(x, offset, region.dim, output.dim, p4s=NULL, ..., half.cell=c(0.5,0.5), OVERRIDE_PROJ_DATUM_WITH_TOWGS84=NULL)
writeGDAL(dataset, fname, drivername = "GTiff", type = "Float32", mvFlag = NA, options=NULL, copy_drivername = "GTiff", setStatistics=FALSE, colorTables = NULL, catNames=NULL)
create2GDAL(dataset, drivername = "GTiff", type = "Float32", mvFlag = NA, options=NULL, fname = NULL, setStatistics=FALSE, colorTables = NULL, catNames=NULL)
GDALinfo(fname, silent=FALSE, returnRAT=FALSE, returnCategoryNames=FALSE, returnStats=TRUE, returnColorTable=FALSE, OVERRIDE_PROJ_DATUM_WITH_TOWGS84=NULL, returnScaleOffset=TRUE)
GDALSpatialRef(fname, silent=FALSE, OVERRIDE_PROJ_DATUM_WITH_TOWGS84=NULL)create2GDAL provides a way
to pass through a file name with driver-required extension for sensitive
drivers set_OVERRIDE_PROJ_DATUM_WITH_TOWGS84 is used. Ignored if the GDAL version is less than “1.8.0” or if the CPLConfigOption variable is already set; see getProjectionRef for further detailsgetRasterData, or
getRasterTable, depending on rotation angles (see below);
see the rgdal documentation for the available options (subsetting
etc.) copy_drivername driver to create a dataset, and copyDatset
to copy to the target driver read.GDAL returns the data in the file as a Spatial object.Usually, GDAL maps will be north-south oriented, in which case the rgdal
function getRasterData is used to read the data, and an object
of class SpatialGridDataFrame-class is returned.Some map formats supported by GDAL are not north-south oriented grids. If
this is the case, readGDAL returns the data as a set of point
data, being of class SpatialPointsDataFrame-class. If the points
are on a 45 or 90 degree rotated grid, you can try to enforce gridding
later on by e.g. using gridded-methods(x)=TRUE.
readGDAL will issue a warning: Y axis resolution
positive, examine data for flipping, when the step is positive, but
this need not mean that the data are flipped. Examine a display of the
data compared with your knowledge of the file to determine whether this
is the case (one known case is interpolation files created under Qgis
up to February 2010 at least). To retreive the correct orientation,
use flipVertical.writeGDAL, if types other than ‘Int32’,
‘Float32’, ‘Float64’ are used, the “mvFlag”
argument should be used to set a no data value other than the default
NA. Note that the flag only replaces NA values in the data being exported
with the value of the argument - it does not mark data values equal to
“mvFlag” as missing. The value is stored in the file being written
in driver-specific ways, and may be used when the file is read. When the
default “mvFlag=NA” is used, no NoDataValue is written to the file,
and the input data is written as is.Also in writeGDAL, the “options” argument may be
used to pass a character vector of one or more options to the
driver, for example ‘options=“INTERLEAVE=PIXEL”’,
or ‘options=c(“INTERLEAVE=PIXEL”,
“COMPRESS=DEFLATE”)’. Typical cases are given in the examples
below; it may also be necessary in some cases to escape quotation markes
if included in the string passed to the driver.
image, asciigrid library(grid)
GDALinfo(system.file("external/test.ag", package="sp")[1])
x <- readGDAL(system.file("external/test.ag", package="sp")[1])
class(x)
image(x)
summary(x)
x@data[[1]][x@data[[1]] > 10000] <- NA
summary(x)
image(x)
x <- readGDAL(system.file("external/simple.ag", package="sp")[1])
class(x)
image(x)
summary(x)
x <- readGDAL(system.file("pictures/big_int_arc_file.asc", package="rgdal")[1])
summary(x)
cat("if the range is not 10000, 77590, your GDAL does not detect big\n")
cat("integers for this driver\n")
y = readGDAL(system.file("pictures/Rlogo.jpg", package = "rgdal")[1], band=1)
summary(y)
y = readGDAL(system.file("pictures/Rlogo.jpg", package = "rgdal")[1])
summary(y)
spplot(y, names.attr=c("red","green","blue"),
col.regions=grey(0:100/100),
main="example of three-layer (RGB) raster image", as.table=TRUE)
data(meuse.grid)
gridded(meuse.grid) = ~x+y
proj4string(meuse.grid) = CRS("+init=epsg:28992")
fn <- tempfile()
writeGDAL(meuse.grid["dist"], fn)
GDALinfo(fn)
writeGDAL(meuse.grid["dist"], fn, setStatistics=TRUE)
GDALinfo(fn)
mg2 <- readGDAL(fn)
proj4string(mg2)
SP27GTIF <- readGDAL(system.file("pictures/SP27GTIF.TIF",
package = "rgdal")[1], output.dim=c(100,100))
summary(SP27GTIF)
image(SP27GTIF, col=grey(1:99/100))
GDALinfo(system.file("pictures/cea.tif", package = "rgdal")[1])
GDALSpatialRef(system.file("pictures/cea.tif", package = "rgdal")[1])
cea <- readGDAL(system.file("pictures/cea.tif", package = "rgdal")[1],
output.dim=c(100,100))
summary(cea)
image(cea, col=grey(1:99/100))
fn <- system.file("pictures/erdas_spnad83.tif", package = "rgdal")[1]
erdas_spnad83 <- readGDAL(fn, offset=c(50, 100), region.dim=c(400, 400),
output.dim=c(100,100))
summary(erdas_spnad83)
image(erdas_spnad83, col=grey(1:99/100))
erdas_spnad83a <- readGDAL(fn, offset=c(50, 100), region.dim=c(400, 400))
bbox(erdas_spnad83)
bbox(erdas_spnad83a)
gridparameters(erdas_spnad83)
gridparameters(erdas_spnad83a)
tf <- tempfile()
writeGDAL(erdas_spnad83, tf, drivername="GTiff", type="Byte", options=NULL)
all.equal(erdas_spnad83, readGDAL(tf))
writeGDAL(erdas_spnad83, tf, drivername="GTiff", type="Byte",
options="INTERLEAVE=PIXEL")
all.equal(erdas_spnad83, readGDAL(tf))
writeGDAL(erdas_spnad83, tf, drivername="GTiff", type="Byte",
options=c("INTERLEAVE=PIXEL", "COMPRESS=DEFLATE"))
all.equal(erdas_spnad83, readGDAL(tf))
x <- GDAL.open(system.file("pictures/erdas_spnad83.tif", package = "rgdal")[1])
erdas_spnad83 <- asSGDF_GROD(x, output.dim=c(100,100))
GDAL.close(x)
summary(erdas_spnad83)
image(erdas_spnad83, col=grey(1:99/100))
tf <- tempfile()
xx <- create2GDAL(erdas_spnad83, type="Byte")
xxx <- copyDataset(xx, driver="PNG")
saveDataset(xxx, tf)
GDAL.close(xx)
GDAL.close(xxx)
GDALinfo(tf)
tf2 <- tempfile()
writeGDAL(erdas_spnad83, tf2, drivername="PNG", type="Byte")
GDALinfo(tf2)
GT <- GridTopology(c(0.5, 0.5), c(1, 1), c(10, 10))
set.seed(1)
SGDF <- SpatialGridDataFrame(GT, data=data.frame(z=runif(100)))
opar <- par(mfrow=c(2,2), mar=c(1,1,4,1))
image(SGDF, "z", col=colorRampPalette(c("blue", "yellow"))(20))
title(main="input values")
pfunc <- colorRamp(c("blue","yellow"))
RGB <- pfunc(SGDF$z)
SGDF$red <- RGB[,1]
SGDF$green <- RGB[,2]
SGDF$blue <- RGB[,3]
image(SGDF, red="red", green="green", blue="blue")
title(main="input RGB")
tf <- tempfile()
writeGDAL(SGDF[c("red", "green", "blue")], tf, type="Byte", drivername="PNG")
t1 <- readGDAL(tf)
image(t1, red=1, green=2, blue=3)
title(main="output PNG RGB")
par(opar)
t0 <- meuse.grid["ffreq"]
fullgrid(t0) <- TRUE
t0$ffreq <- as.integer(t0$ffreq)-1
# convert factor to zero-base integer
CT <- c("red", "orange", "green", "transparent")
CT
cN <- c("annual", "2-5 years", "infrequent")
tf <- tempfile()
writeGDAL(t0, tf, type="Byte", colorTable=list(CT), catNames=list(cN),
mvFlag=3L)
attr(GDALinfo(tf, returnStats=FALSE, returnCategoryNames=TRUE),
"CATlist")[[1]]
ds <- GDAL.open(tf)
displayDataset(ds)
t(col2rgb(getColorTable(ds)[1:4]))
GDAL.close(ds)
fn <- system.file("pictures/test_envi_class.envi", package = "rgdal")[1]
Gi <- GDALinfo(fn, returnColorTable=TRUE, returnCategoryNames=TRUE)
CT <- attr(Gi, "ColorTable")[[1]]
CT
attr(Gi, "CATlist")[[1]]
with <- readGDAL(fn)
with <- readGDAL(fn, silent=TRUE)
table(with$band1)
table(as.numeric(with$band1))
with1 <- readGDAL(fn, as.is=TRUE)
table(with1$band1)
spplot(with, col.regions=CT)
tf <- tempfile()
cN <- levels(with$band1)
with$band1 <- as.integer(with$band1)-1
writeGDAL(with, tf, drivername="ENVI", type="Int16", colorTable=list(CT),
catNames=list(cN), mvFlag=11L)
cat(paste(readLines(paste(tf, "hdr", sep=".")), "\n", sep=""), "\n")
wGi <- GDALinfo(tf, returnColorTable=TRUE, returnCategoryNames=TRUE)
CTN <- attr(wGi, "ColorTable")[[1]]
CTN
attr(wGi, "CATlist")[[1]]
withN <- readGDAL(tf)
table(withN$band1)
withN1 <- readGDAL(tf, as.is=TRUE)
table(withN1$band1)
spplot(withN, col.regions=CTN)
# a file with scale and offset
fn <- system.file("pictures/scaleoffset.vrt", package = "rgdal")[1]
g <- GDALinfo(fn)
attr(g, 'ScaleOffset')
g
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