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@tyrasd /
Last active May 5, 2016

This is how I've visualized OpenStreetMap's node density.
  1. download the source data

  2. convert to simple, gnuplot-readable text format

    sed 's/\([0-9]*\) z=\([0-9]*\) x=\([0-9]*\) y=\([0-9]*\)/\3 \4 \1/' < tiles.13 > tiles.13.txt
    sed 's/\([0-9]*\) z=\([0-9]*\) x=\([0-9]*\) y=\([0-9]*\)/\3 \4 \1/' < tiles.16 > tiles.16.txt
  3. start gnuplot

  4. use gnuplot to create the map

    unset xtics
    unset ytics
    unset border
    unset key
    unset legend
    unset title
    set lmargin at screen 0
    set tmargin at screen 0
    set rmargin at screen 1
    set bmargin at screen 1
    set palette rgbformulae 34,35,36
    width = 1024
    set xrange [0:width-1]
    set yrange [0:width]
    set object rectangle from screen 0,0 to screen 1,1 fillcolor rgb"#000000" behind
    set terminal png size width,width
    set output "density.13.png"
    plot 'tiles.13.txt' using ($1/8):(width-1-$2/8):(log($3)) with dots palette
  5. repeat with zoom-16 tiles (don't forget to adapt the numbers above)

  6. results and more information

femtope commented May 5, 2016

Please Fred, is there a way to specify for Africa alone.

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