I am trying to create a high resolution file of a geographic area about 10 miles in diameter to order an image that will print on a wallpaper for a wall 110" tall and 140" wide. I need at least 300 dpi.
Thank you.
The simplest (no software installation) and cheapest (no design agency to contract) way for this is likely the web site print.get-map.org. It might not do quite the 300 dpi that you ask for but it will come close (and let’s be honest, you will only need 300 dpi on a wallpaper if you intend to read street names with a magnifying glass).
You could also look into the free (as in: no money to pay, not: free software) software maperitive.net which will allow you to generate an Illustrator-compatible SVG file for the area of interest, and your printer should be able to process that.
Or you could go to the length of installing a PostGIS database, mapnik, openstreetmap-carto, osm2pgsql, and the “nik4.py” utility, then download the OSM Data for the region of interest, and render a high-resolution PNG yourself. Much of what you’d be doing is described on switch2osm.org - only in the end you’d deviate from that by using nik4 instead of mod_tile and renderd.
140×110×300×300 ~ 1400 M pixels.
A .png that size would be some 1,5 GB (1.5 for Americans).
Which area? Please show us a screenshot of Openstreetmap with a rectangle 14:11 on it.
What style do you need? For the concern above, topography maps with colored elevations will have more pixel variation, probably increasing the file size. Do you need land-cover?
How will it be printed? Won’t you actually need to split it to smaller parts in the end anyway?
Any requirements on color? The CYMK vs RGB difference? Almost all readily available maps are designed for electronic displays.