Geographic Information Systems Asked by Floni on July 22, 2021
I have a raster file and I would like to save it to be able to open it with a attribute table in ArcMap.
When I use the command writeRaster(raster, "test_output11", format = "GTiff"), I don´t have the aux files such as .tfw, .xml, .ovr, .cpg, .dbf.
Should I produce all the files manually by changing format = "GTiff"? I can ´t find a general command for it.
Those files are generated in ArcGIS. Are auxiliary files for georeferencing and visualization, aren't part of GTiff as .shx or .dbf are in a shapefile.
.tfw is ESRI World file.ovr are piramid layers.xml is schema look and histogram.cpg is for TIFF interpretation..dbf is for raster attribute table (thanks to @radouxju)You can add .tfw using GDAL through raster package:
library(raster)
r <- raster()
values(r) <- sample(x = 1:10,size = ncell(r),replace = T)
writeRaster(r,'test.tif',options=c('TFW=YES'))
Check other options from GDAL GeoTIFF File Format to customize your export.
Correct answer by aldo_tapia on July 22, 2021
You need to ratify your raster and give it some attributes, then write to GTiff format. Both a .tif and a .tif.aux.xml file will be written out, and ArcGIS can use the latter to derive symbology (QGIS sadly doesn't...). Example:
library(raster)
set.seed(1)
r <- raster(matrix(sample(c(1, 7:9, 19), 100, replace=TRUE), 10))
r <- ratify(r)
levels(r)[[1]]$NAME <- letters[1:nrow(levels(r)[[1]])]
# check results with levels(r)[[1]]
writeRaster(r, 'C:/DATA/r.tif')
Note that there's not much point doing this with continuous data, such surfaces should be reclassified first.
If you want a .dbf RAT that Arc will pick up automatically, this will work:
# datatype must be integer and raster must be single band
writeRaster(r, 'C:/DATA/r_2.tif', datatype = 'INT2S')
library(tidyverse)
as.data.frame(table(as.vector(r)),
stringsAsFactors = FALSE) %>%
rename(VALUE = Var1, COUNT = Freq) %>%
# you can add some more cols here,
# just keep nchar() < 254 and colnames < 8 chars:
mutate(VALUE = as.integer(VALUE)) %>%
foreign::write.dbf(., 'C:/DATA/r_2.tif.vat.dbf',
factor2char = TRUE, max_nchar = 254)
Answered by obrl_soil on July 22, 2021
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