[Λήψη δορυφορικών εικόνων στην R μέσω του GIBS API] #GIBS

rgibs.R

library(gdalUtils)

rGIBS<-function(date=Sys.Date(), EPSGCODE,PRODUCT,projwin, outputdir=file.path(Sys.getenv("HOME"),"gibs_downloads"),...){
  dir.create(outputdir, showWarnings = FALSE)
  setwd(outputdir)
  #generate xml
  makeXML <- function(date, EPSGCODE,PRODUCT){
    myxml<- sprintf('<GDAL_WMS><Service name="TiledWMS"><ServerUrl>https://gibs.earthdata.nasa.gov/twms/epsg%s/best/twms.cgi?</ServerUrl><TiledGroupName>%s tileset</TiledGroupName><Change key="${time}">%s</Change></Service></GDAL_WMS>',EPSGCODE, PRODUCT, date)
    tmp <- tempfile(fileext=".xml")
    fileConn<-file(tmp)
    writeLines(myxml, fileConn)
    close(fileConn)
    return(tmp)
  }
  
  infile<-makeXML(date,EPSGCODE,PRODUCT)
  outfile<-gsub(" ","_",(sprintf('%s_%s_EPSG%s.tif',PRODUCT,date,EPSGCODE)))
  
  
  gdal_translate(
    infile,
    outfile,
    projwin=projwin,
    verbose = T,
    ...
  )
  
  
  #delete temp file
  unlink(infile)
  message(sprintf("Image %s was saved in %s", outfile, outputdir))
  return (file.path(outputdir,outfile))
  
}

PRODUCT<-'VIIRS SNPP DayNightBand ENCC'
EPSGCODE<-4326
date<-'2017-08-15'
projwin <- c(19.07, 42.16, 28.39, 34.5)

image<-rGIBS(date=date,EPSGCODE=EPSGCODE,PRODUCT=PRODUCT, projwin=projwin, of = "GTiff")
plotRGB(stack(image))

dates<-seq(as.Date("2017/11/08"), as.Date("2017/11/09"), "days")

myresults<-lapply(
  dates,
  rGIBS,
  EPSGCODE=EPSGCODE,
  PRODUCT=PRODUCT,
  projwin=projwin,
  of = "GTiff"
  )