Get the Mapnik stylesheets

.bash_profile

export MAPNIK_INSTALL=/Library/Frameworks/Mapnik.framework/unix
export PROJ_LIB=${MAPNIK_INSTALL}/share/proj
export ICU_DATA=${MAPNIK_INSTALL}/share/icu
export GDAL_DATA=${MAPNIK_INSTALL}/share/gdal

generate_image.sh

./generate_xml.py --dbname paris_cod --host [host] --user [userdatabase] --port 5432 --password [theuserpassword]

get_shape.sh

./get-coastlines.sh

mapnik-stylesheets.sh

git clone https://github.com/openstreetmap/mapnik-stylesheets
cd mapnik-stylesheets

Resolution-calcul-exemple

Units Conversion Factor
inches        1
ft           12
mi        63360
m       39,3701
km      39370,1
dd      4374754      Decimal Degrees
in            1

Setup 
dpi          72      Screen dots per inch            
Units        dd      Units our map is in for OpenLayers            
Factor  4374754      Scale factor based on units.

Bounding Box 
(-122,1655000,43,0083000,-122,1077000,42,9505000 )
Left         -122,1655000                  
Right        -122,1077000                  
Top            43,0083000                  
Bottom         42,9505000     

Map DIV               The size of the area on the webpage the map will go in.
WIDTH         600     pixel
HEIGHT        600     pixel

dx         = Left - Right
Scale      = dx/WIDTH * dpi * Factor
Resolution = dx/WIDTH

dx                  0,0578     
dy                  0,0578     
Scale          30343,29374                  
Resolution  0,000096333333