[R-sig-Geo] How to export a GeoTIFF 8 bit raster

[Michael Sumner]

this might work, your file link doesn't provide access to me so I created a
guess example

library(terra)
x <- rast(matrix(sample(0:255, 12), 3))
file.tif <- tempfile(fileext = ".tif")
#writeRaster(x, file.tif, gdal = "NBITS=8", datatype = "INT1U")
#rast(file.tif)

terra has its own controls over the options, some interact/overlap with the
gdal ones I haven't explored that

HTH,  Mike

On Mon, Jan 31, 2022 at 5:52 AM Rik Ferreira <rikferreiraalves using gmail.com>
wrote:
>
> Hello!
>
> How a raster image can be exported as a 8 bit GeoTIFF image?
>
> I'm downloading a 8 bit image from this link:
> http://geoinfo.cnps.embrapa.br/documents/2918/download, cropping it with a
> vector mask, treating it, and exporting it with terra package (writeRaster
> function).
>
> However, the original image is a GeoTIFF with 8 bit depth but the output
> image (terra package, writeRaster function) is a 32 bit image.
>
> I can control it with `gdal = "NBITS=8"` argument to writeRaster but i get
> such warning:
>
> Warning message:
> > In x using ptr$writeRaster(opt) :
> >   GDAL Message 6:
> > /mnt/HDD/STORAGE/r-projects/raster-bit-depth/output/recorte.tif: Only
> > NBITS=16 is supported for data type Float32
> >
>
> How can I export this raster as a 8 bit GeoTIFF image with terra package?
>
> --
> Rik Ferreira Alves
> Graduando em Geografia - Unimontes
> https://rikferreira.netlify.app/
>
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>
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--
Michael Sumner
Software and Database Engineer
Australian Antarctic Division
Hobart, Australia
e-mail: mdsumner using gmail.com

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