Tile Map
Peta yang ada di Web sekarang ini banyak menggunakan tile map. Tile map menampilkan peta memakai gambar-gambar kecil dalam grid berbentuk persegi. Gambar yang diunduh sesuai dengan luas yang sedang dilihat pada level zoom, bujur maupun lintang tersebut. Gambar-gambar kecil tersebut biasanya berformat PNG karena memiliki ketajaman yang lebih baik dibandingkan format JPEG terutama pada garis dan batas antara dua warna.
Pada umumnya peta tile map ini memiliki zoom dari 1 yaitu mencakup keseluruhan bumi dan zoom 17 untuk melihat rumah-rumah. Jumlah gambar pada setiap level adalah perkalian antara x (bujur) dan y (lintang). Berikut tabel jumlah gambar per level.
| Level | X | Y | Jumlah |
|---|---|---|---|
| 2 | 0-3 | 0-3 | 16 |
| 3 | 0-7 | 0-7 | 64 |
| 4 | 0-15 | 0-15 | 256 |
| 5 | 0-31 | 0-31 | 1024 |
| 6 | 0-63 | 0-63 | 4096 |
| 7 | 0-127 | 0-127 | 16384 |
| 8 | 0-255 | 0-255 | 65536 |
| 9 | 0-511 | 0-511 | 262144 |
Unduh
Pengunduhan gambar dengan jumlah banyak tersebut penulis menggunakan curl. Berikut perintah yang digunakan untuk melakukan pengunduhan.
curl --output '#1_#2.png' 'http://a.tiles.telegeography.com/maps/submarine-cable-map-2014/6/[0-63]/[0-63].png'
Gabung Gambar
Penggabungan gambar menggunakan program ImageMagick.
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| #!/bin/bash | |
| function show_help | |
| { | |
| echo "Usage: $0 (-x xcoord) (-y ycoord) (-l level)" | |
| echo " [-r x width] [-s y width] -h for help" | |
| } | |
| if [ $# -le 1 ]; then | |
| show_help | |
| exit 1 | |
| fi | |
| # A POSIX variable | |
| OPTIND=1 # Reset in case getopts has been used previously in the shell. | |
| ## Note !1e0=png !1e3=webp !1e4=bin | |
| G_SAT='https://www.google.com/maps/vt/pb=!1m5!1m4!1i$level!2i[$x-$x1]!3i[$y-$y1]!4i128!2m2!1e1!3i803!3m9!2sid!3sid!5e1105!12m1!1e4!12m1!1e47!12m1!1e3!4e0!5m1!1e0' | |
| G_SAT_1='https://www.google.com/maps/vt/pb=!1m5!1m4!1i$level!2i[$x-$x1]!3i[$y-$y1]!4i128!2m2!1e1!3i803!3m9!2sid!3sid!5e1105!12m1!1e4!12m1!1e47!4e0!1e0' | |
| G_MAP='https://www.google.com/maps/vt/pb=!1m5!1m4!1i$level!2i[$x-$x1]!3i[$y-$y1]!4i128!2m2!1e0!3i429133041!3m7!2sid!3sid!5e1105!12m1!1e47!12m1!1e3!4e0!5m1!1e0' | |
| G_CON_0='https://www.google.com/maps/vt/pb=!1m4!1m3!1i$level!2i[$x-$x1]!3i[$y-$y1]!2m2!1e5!2sshading!2m2!1e6!2scontours!2m3!1e0!2sm!3i429133076!3m7!5e1105!12m1!1e67!12m1!1e63!12m1!1e3!4e0!5m2!5f1!6b1' | |
| G_CON_1='https://www.google.com/maps/vt/pb=!1m4!1m3!1i$level!2i[$x-$x1]!3i[$y-$y1]!2m2!1e5!2sshading!2m2!1e6!2scontours!2m3!1e0!2sm!3i429133076!3m7!5e1105!12m1!1e67!12m1!1e63!5f1!6b1' | |
| SOURCE_URL=$G_SAT | |
| X_WIDTH=10 | |
| Y_WIDTH=10 | |
| EXT="png" | |
| ANNOTATE=false | |
| while getopts ":x:y:r:s:l:h?" opt; do | |
| case $opt in | |
| x ) x=$OPTARG ;; | |
| y ) y=$OPTARG ;; | |
| l ) level=$OPTARG ;; | |
| r ) X_WIDTH=$OPTARG ;; | |
| s ) Y_WIDTH=$OPTARG ;; | |
| h ) show_help; exit 0 ;; | |
| \? ) echo "Invalid option: -$OPTARG" >&2; exit 1 ;; | |
| : ) echo "Option -$OPTARG requires an argument." >&2; exit 1 ;; | |
| esac | |
| done | |
| shift $((OPTIND-1)) | |
| if [ -z "$x" -o -z "$y" -o -z "$level" ]; then | |
| echo "Option -x -y -l required" | |
| exit 1 | |
| fi | |
| echo "x: $x, y: $y, level: $level, xrange: $X_WIDTH, yrange: $Y_WIDTH" | |
| function calculate | |
| { | |
| let x1=x+$X_WIDTH | |
| let y1=y+$Y_WIDTH | |
| eval URL="$SOURCE_URL" | |
| echo $URL | |
| } | |
| function fetch | |
| { | |
| echo "==> Downloading" | |
| curl -C - --output "#1_#2.${EXT}" "$URL" | |
| } | |
| function merge | |
| { | |
| mkdir 'out' | |
| if $ANNOTATE; then | |
| echo "==> Annotating" | |
| mogrify -gravity South \ | |
| -annotate +0+5 '%f' \ | |
| -pointsize 11 \ | |
| -fill white \ | |
| -bordercolor '#DFDFDF' \ #grey | |
| -border 1 *.${EXT} | |
| fi | |
| echo "==> Merging" | |
| for ((c=$x; c<=$x1; c++)); | |
| do | |
| echo $c | |
| if [ $x -lt 10 ]; then | |
| for ((i=0; i<=9; i++)); | |
| do | |
| echo -n "rename ${c}_${i} "; | |
| a=${c}_${i}.${EXT}; | |
| j=`echo $a | cut -d _ -f 2` ; | |
| mv $a `printf ${c}_0${j}`; | |
| done | |
| fi | |
| montage -verbose \ | |
| -mode concatenate \ | |
| -tile 1x ${c}\_*.${EXT} out/${c}.${EXT} | |
| done | |
| cd 'out' | |
| for ((a=0; a<=9; a++)); # $(seq 0 1 9) | |
| do | |
| if [ -z ${a}.${EXT} ]; then | |
| mv ${a}.{EXT} 0${a}.${EXT}; | |
| fi | |
| done; | |
| let START_POS=x/10 | |
| let END_POS=x1/10 | |
| let DIFF=$END_POS-$START_POS | |
| for ((a=START_POS; a<=END_POS; a++)); | |
| do | |
| montage -verbose \ | |
| -mode concatenate \ | |
| -tile x1 ${a}*.${EXT} F${a}.${EXT} | |
| done; | |
| if [ $DIFF -gt 3 ]; then | |
| let HALF=$START_POS+$DIFF/2 | |
| let NEXT=$HALF+1 | |
| montage -verbose \ | |
| -mode concatenate \ | |
| -tile x1 $(eval echo F{${START_POS}..${HALF}}.${EXT}) L.${EXT} | |
| montage -verbose \ | |
| -mode concatenate \ | |
| -tile x1 $(eval echo F{${NEXT}..${END_POS}}.${EXT}) R.${EXT} | |
| montage -verbose \ | |
| -mode concatenate \ | |
| -tile x1 L.${EXT} R.${EXT} FINAL.${EXT} | |
| else | |
| montage -verbose \ | |
| -mode concatenate \ | |
| -tile x1 $(eval echo F{${START_POS}..${END_POS}}.${EXT}) FINAL.${EXT} | |
| fi | |
| cd ".." | |
| echo "==> Done merging" | |
| } | |
| function cleanup | |
| { | |
| echo "==> Cleanup" | |
| mkdir "source" | |
| mv *.${EXT} source/ | |
| mv out/FINAL.${EXT} . | |
| convert -resize 1366x\> FINAL.${EXT} RE1000.${EXT} | |
| } | |
| function main | |
| { | |
| mkdir "${level}-${x}-${y}" | |
| cd "${level}-${x}-${y}" | |
| calculate | |
| fetch | |
| merge | |
| cleanup | |
| } | |
| main |