If the illuminated areas are a very small portion of the entire map, then the circle metaphor actually may be more appropriate. But I see your point. Hmm... P

If the illuminated areas are a very small portion of the entire map, then the circle metaphor actually may be more appropriate. But I see your point. Hmm... Perhaps better still would be an immense valley of very uneven steepness and roughness, that we are climbing out of.