Use raster
package to convert your files to .tif before loading them in QGIS. I will use a reproducible example from the package example:
library(bfastSpatial)
srdir <- dirout <- file.path(dirname(rasterTmpFile()), 'bfmspatial_2')
dir.create(dirout, showWarning=FALSE)
# Get the directory where the Landsat archives are stored
dir <- system.file('external', package='bfastSpatial')
# Run the batch line
processLandsatBatch(x=dir, pattern=glob2rx('*.zip'), outdir=dirout, srdir=srdir, delete=TRUE, vi='ndvi', mask='fmask', keep=0, overwrite=TRUE)
list <- list.files(dirout, pattern=glob2rx('*.grd'), full.names=TRUE)
The above code creates a .grd image. Now use raster package to convert files.
r <- raster::raster(list[[1]])
raster::writeRaster(r,filename = "image_name", format = "GTiff")
Also, you can create a loop to automate all the process.
for(i in 1:length(list)){
r <- raster::raster(list[[i]])
name <- gsub(pattern = ".*bfmspatial_2/",replacement = "", r@file@name) # your folder here (pattern)
name <- gsub(pattern = ".grd",replacement = "", name)
raster::writeRaster(r,filename = name, format = "GTiff")
}
I hope it helps you