Would you be interested in a 3D map that allows you to place a virtual camera at a certain location, adjust focal length and aperture, play with framing, and preview you photo? Think of it as 3D Google Maps with photography-specific tooling.
Would you also like to visualise sunlight conditions for your virtual scene so that you know the ideal time to go to the location to take an actual picture?
This surely can be really useful for landscape and architecture shots because exploring different angles and framing in real life can take some time, and a digital map would allow to speed up the workflow.
When it comes to data, the only high-quality digital 3D model of the world with good coverage is Google Maps. Luckely, they've recently opened access to their 3D data for app developers. For example, here's how Golden Gate Bridge looks like: https://i.imgur.com/wl2drhQ.png
If you've ever used Google Maps then you know that it only has 3D data coverage in large cities, but this is as good as it gets for now when it comes to 3D data.
I'm just brainstorming ideas related to maps, this seems like an interesting one.