Open Street Map RL Wallpaper…

We wanted to paint one wall in our vestibule to add a little more color to the room. As we could not settle on a specific color, I thought of wallpaper. And is there any better theme than OpenStreetMap Data¹?

 
The theme was settled. It had to be a map, but which tiles? I thought of the beautiful pencil drawn MapBox tiles I saw some time ago:

We wanted some redish color so I had to convert the image with ImageMagick:

#!/bin/bash
# I found this script in the imagemagick formus:
# http://www.imagemagick.org/discourse-server/viewtopic.php?t=17460#p91820
# It does about the same as gimp with the colorize option.
test -z $1 && exit -1

hue=$1
sat=50
light=0
hue=`convert xc: -format "%[fx:100*$hue/360]" info:`
sat=`convert xc: -format "%[fx:2*$sat]" info:`
test=`convert xc: -format "%[fx:$light<0?0:1]" info:`
light=`convert xc: -format "%[fx:abs($light)]" info:`
if [ $test -eq 0 ]; then
fillcolor="black"
else
fillcolor="white"
fi

convert \
$2 -set colorspace RGB -colorspace gray -set colorspace sRGB \
-fill "hsl($hue%,100%,50%)" -tint 40% \
-modulate 100,$sat,100 \
-fill $fillcolor -colorize $light% $3

the result is something like this:

I crawled more™ tiles with the OpenstreetMap Bigmap script, but changed the source to MapBox’s servers for their pencil drawn tiles:

#!/usr/bin/perl

# generated from http://openstreetmap.gryph.de/bigmap.cgi/
# permalink for this map: http://openstreetmap.gryph.de/bigmap.cgi?xmin=71104&xmax=71231&ymin=45952&ymax=46143&zoom=17&scale=256&baseurl=http%3A%2F%2Ftile.openstreetmap.org%2F!z%2F!x%2F!y.png
#
use strict;
use LWP;
use GD;

my $img = GD::Image->new(32768, 49152, 1);
my $white = $img->colorAllocate(248,248,248);
$img->filledRectangle(0,0,32768,49152,$white);
my $ua = LWP::UserAgent->new();
$ua->env_proxy;
for (my $x=0;$x<128;$x++)
{
    for (my $y=0;$y<192;$y++)
    {
        my $xx = $x + 71104;
        my $yy = $y + 45952;
        # changed the path here:
        foreach my $base(split(/\|/, "https://c.tiles.mapbox.com/v3/examples.a4c252ab/17/!x/!y.png"))
	{
		my $url = $base;
                $url =~ s/!x/$xx/g;
                $url =~ s/!y/$yy/g;
		print STDERR "$url... ";
		my $resp = $ua->get($url);
		print STDERR $resp->status_line;
		print STDERR "\n";
		next unless $resp->is_success;
		my $tile = GD::Image->new($resp->content);
		next if ($tile->width == 1);
		if ($base =~ /seamark/) {
		my $black=$tile->colorClosest(0,0,0);
		$tile->transparent($black);
		}
		$img->copy($tile, $x*256,$y*256,0,0,256,256);
	}
    }
}
binmode STDOUT;
print $img->png();

Finally I had a 32,768 x 49,152 pixel PNG file with 324 MB. Scaling it the first time on my laptop took 8 hours. To colorize it the right way I found myself a machine with a little more ram. The final file was 20,110 x 35,000 pixels with a possible resolution of 340 dpi. It almost killed the windows machine at the copyshop but the results were really nice.