Yeah this is something I've been thinking about recently, not so much in terms of the difficulty of managing spam on a per post basis, as I'm thinking that the instances will be very small and moderation on that front should be easy, so long as you can keep the problematic user from signing up in the first place. One thing I've been thinking is that perhaps there could be a captcha-like solution that will benefit from the limited location. For instance: Select only images that are of this location. Local users will know, bots will struggle. It doesn't stop anyone else from using Google street view or something but it does make the bar the bit higher. I don't know how to deal with the obvious accessibility issue with this though so I'm going to keep it in mind until I get around to that sort of thing. Long term of course we're going to have the issue with federated spam also, so I don't want to implement a solution that will only be in my way in the long run.

> there could be a captcha-like solution that will benefit from the limited location. For instance: Select only images that are of this location. Local users will know, bots will struggle.

Hah, that is a fun idea! But it could be a challenge to implement, unless you have a trusted person in that location selecting an image or some other local funfact – and at that point you might as well implement a graph of trust, spreading out from the first user in that area. Kind of like an invite system, where everyone vouches for the next one they invite in.

Come to think of it, having a limiting factor that an invite system imposes, might make the whole concept more attractive and a bit mystical, as it takes some effort to access the network.

I can see a lot of challenges implementing this though, but it is fun to explore different new directions this could take!

Thanks, I'll give the trust system some thought. These are both systems that could be turned on or off per instance so I'm theory they could both exist. I was thinking that the instance administrator would have to be the one to prove the images for the captcha.