Grab images of Earth from the Himawari-8 satellite

himawari-grabber.sh

#!/bin/bash

# Fetch full-resolution Earth images from the Himawari-8 satellite
# Requires ImageMagick, curl, Perl

# The URL structure of the image server is liable to change, but currently looks like this:
# Typical url = https://himawari8-dl.nict.go.jp/himawari8/img/D531106/20d/550/YYYY/MM/DD/hhmm00_XX_YY.png
#  YYYY/MM/DD = date
#  hhmm = UTC time (rounded to 10 minutes)
#  XX, YY = X and Y coordinates of tile (0 <= XX, YY <= 19)

# Images updated every 10 minutes, but take about 20 minutes to go online
# Generate timestamp data for the URL and output filename
t=`date -u -v-22M "+%Y/%m/%d/%H%M" | head -c 14`"000"
t0=`echo $t | sed s/[^0-9]/-/g`
baseurl="https://himawari8-dl.nict.go.jp/himawari8/img/D531106/20d/550/$t"_

# Create a random prefix for temp file names
rr=`cat /dev/urandom | xxd -p | head -c32`

# Progress bar width
pw=60

# Images are served as a 20x20 mosaic of 550x550 pixel PNG images
for i in {0..19} ; do
    for j in {0..19} ; do
        curl -s "$baseurl$i"_"$j.png" > /tmp/$rr-$i-$j.png
        perl -e '$w='"$pw"'; $p='"$[i * 20 + j]"'; $x=int($p*$w/400+.5); $y=$w-$x; print "\rDownloading [\33[32m", "#" x $x, "-" x $y, "\33[0m]";'
    done
done
echo " Done"

# Assemble each column
for i in {0..19} ; do
    convert -append `ls /tmp/$rr-$i-* | sort -t- -k3 -n` /tmp/slice-$rr-$i.png
    perl -e '$w='"$pw"'; $p='"$i"'; $x=int($p*$w/25+.5); $y=$w-$x; print "\rStitching   [\33[32m", "#" x $x, "-" x $y, "\33[0m]";'
done

# And now stitch the columns together
convert +append `ls /tmp/slice-$rr-* | sort -t- -k3 -n` "earth-$t0.png"
perl -e '$w='"$pw"'; print "\rStitching   [\33[32m", "#" x $w, "\33[0m]";'

# Remove the temporary files
rm /tmp/$rr-*
rm /tmp/slice-$rr-*

echo " Done"
echo -e "\x1B[32mCreated file earth-$t0.png\x1B[0m"