There’s all kinds of reasons you might want to have a map on a poster. Demographic data, species ranges, voting results, and much, much more.
Sometimes, a map might be available in the literature that you can scan.
Of course, anytime you’re using someone else’s work, you may have problems. For instance, I’m only interested in species labeled 4 on the map (from Efford, 1971), which is the range for Lepidopa benedicti, a local crab. I could go in with a graphics editor and try cleaning it up, but that can be time consuming.
Google Maps is a useful tool for making quick and dirty maps if you have location data of some sort. For instance, here I was able to take data for the crab species from another paper that had location information (Boyko 2002).
Google Maps is an amazing tool for organizing location data, but to get a Google map onto a poster, the only method I know is to do a screen grab. Screen grabs always leave a lot to be desired. It’s a pixel-based image, and you’re limited by the size of your screen, which might not be high enough resolution for a large poster. And the Google Map has a lot of extra stuff on it that you might not want.
I’ve been playing around with the cloud software Indiemapper for some time. You can import data from Google Maps into it, and plot it in a large number of ways:
I’m just using this for simple location points, but you can also use this to make maps that show all manner of stats associated with different locations.
Indiemapper allows you to export your maps in a vector-based format (SVG), or as high a pixel count as JPG or PNG file as you want. You want a 10 inch map at 300 dpi? You can tell Indiemapper to make your exported PNG file 3000 pixels wide.
They offer a 30 day free trial and a discount pricing scheme for academics.
Boyko CB. 2002. A worldwide revision of the recent and fossil sand crabs of the Albuneidae Stimpson and Blepharipodidae, new family (Crustacea, Decapoda, Anomura, Hippoidea). Bulletin of the American Museum of Natural History 272: 1-396. doi: 10.1206/0003-0090(2002)272<0001:AWROTR>2.0.CO;2
Efford IE. 1971. The species of sand crabs in the genus Lepidopa (Decapoda: Albuneidae). Zoologischer Anzeiger 186: 59-102.