I recently needed to create a big georeferenced image from a mapnik style file, and found out no image exporting tool currently offers more than a direct interface to mapnik's options. That is, I could not get "image in 300 dpi for printing on an A5 sheet", I had to understand what scale_factor is, and what is the default resolution, and why lines had become so thick. And I'm a programmer — imagine a confusion of a regular user!
Today I have published Nik4. It makes everything easier.
Grab a 800x600 image at z13?
-c LON LAT -x 800 600 -z 13 — and no suprises like when the output image differs from osm.org (nik2img puzzled me with that one). Print a region in 300 dpi on A5?
-a 5 --ppi 300 --bbox X1 Y1 X2 Y2. You don't have to think about scale_factor ever. Make a very large image? No problem, use
--tiles 4 and wait a bit; you won't run out of memory.
See https://github.com/Zverik/Nik4 for an extensive description and installation instructions (
easy_install nik4 — there, no more instructions needed). Print more maps.
And for generating tiles there is just as simple polytiles.py.