I see you're sourcing images from Wikimedia. Have you found any other good sources? I'm working on indexing images by place taken for my own project and am primarily very slowly and jankily enumerating the flickr API. (You can see https://plantopo.com/geophotos for a pre-alpha view of where I have coverage. Zoom in where there are blue dots and click the map to search. Don't click Oregon or Washington because of a bug I'm working on)
Wikimedia is a totally underrated source of photos.
The problem is filtering good ones. See my PR of the day, where I'm using only the images that are featured on Wikipedia pages. It gives better results than google maps in lots of places. Also some weird pictures like logos but I'm confident they can be ruled out.
My project is for planning hiking trips so the areas I'm searching typically are places in the wilderness that don't have many photos. Right now I'm not doing any ranking. I just semi-randomly take ten photos for the search area.
Are you using opentripplanner for routing?