#' SentinelThumbnailPreview
#'
#' Preview small sentinel thumbnail images to determine which images are good for use and cloud free
#' @param sentinel.df a dataframe generated from function SentinelSearchToDF()
#' @param thumbnail.dir folder directory to store thumbnail images in
#' @param musr Copernicus Open Access Hub user name (authentication)
#' @param mpass Copernicus Open Access Hub password (authentication)
#' @return Dataframe of search results
#' @export
SentinelThumbnailPreview <- function(
sentinel.df=NA,
thumbnail.dir = NA,
musr=NA,
mpass=NA
){
if(FALSE){
sentinel.df=sentdf
thumbnail.dir = samp_thumbnail_dir
}
for(i in 1:nrow(sentinel.df)){
this_thumb <- paste0(as.character(sentinel.df$thumbnail[i]), "Products('Quicklook')/$value")
filename = paste0(thumbnail.dir, "/", sentinel.df$filename[i], ".png")
link <- URLencode(this_thumb, reserved = FALSE, repeated = FALSE)
this_resp <- GET(link, authenticate(musr, mpass))
this_img <- content(this_resp)
if(class(this_img) != "array"){
print("no preview")
png(filename, width=6, height=6, units="in",res=300)
plot(0:1, 0:1, type = "n", axes=FALSE, frame.plot=FALSE, xlab="", ylab="", main=sentinel.df$filename[i])
text(0.5, 0.5, "No preview")
dev.off()
next
}
# Save output
png(filename, width=12, height=12, units="in",res=300)
plot(0:1, 0:1, type = "n", axes=FALSE, frame.plot=FALSE, xlab="", ylab="", main=sentinel.df$filename[i], sub=sentinel.df$summary[i])
rasterImage(this_img, 0, 0, 1, 1)
dev.off()
}
}
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