gistfile1.sh

#!/bin/bash
set -e -u

# 1. render each layer of each zoom level
# 2. combine each layer of each zoom level to one image in a specified manner
# 3. cut each layer into 

#### CONFIGURATION ####

ZMIN=0
ZMAX=5

MAPFILE="land-glow.mml"
TMPDIR="layers"
FINALDIR="/home/aj/Dropbox/geo-un-world/renders"

#### PROGRAM ####

## RENDER BACKGROUND TILES

for L in `seq $ZMIN $ZMAX`; do

  # Determine output dimensions based on zoomlevel
  Zd=$((256*(2**$L)))

  # Render with Mapnik
  nik2img.py --no-open \
    -d $Zd $Zd \
    -e -20037508 -20037508 20037508 20037508 \
    "$MAPFILE" "$TMPDIR/land_glow_z$L.png"

  # Generate transparency with ImageMagick
  convert \
    -size ${Zd}x${Zd} xc:black \
    "$TMPDIR/land_glow_z$L.png" -alpha Off \
    -compose Copy_Opacity -composite \
    -format tiff -depth 8 -monochrome -alpha On \
    "$TMPDIR/land_glow_trans_z$L.tif"

  # Make geotiff with gdal
  gdal_translate \
    -a_ullr -20037508 20037508 20037508 -20037508 \
    -a_srs "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs" \
    -co alpha=yes \
    "$TMPDIR/land_glow_trans_z$L.tif" \
    "$FINALDIR/land_glow_z$L.tif"

done