Well, you could look for topographic features that would shout 'funnel'. Areas like saddles, ridges and steep cliffs might be a good place to start. You might also want to see if there are any rivers or ponds on that area. Where I hunt it is more or less flat or just rolling hills and it is hard to find any funnels unless you search the area in person. An arial or satalite map can be helpfull too, if available for the area you plan on hunting.