One tricky thing about maps, as they relate to privacy, is that the earth is large.
Compare that to encrypted email: if I’m sending you an encrypted message, the total data involved is minimal. To a first approximation, it’s just the message contents.
But if I want “Google Maps but private,” I first need access to an entire globe’s worth of data, on the order of terabytes. That’s a lot of storage for your (usually mobile) client, and a lot of bandwidth for whoever delivers it. And that data needs to be refreshed over time.
Typical mapping applications (like Google Maps) solve this with a combination of network services that answer your questions remotely (“Tell me what you’re searching for, and I’ll tell you where it is.”) and by tiling data so your client can request exactly what it needs, and no more, which is also a tell.
The privacy focused options I see are:
1. Pre-download all the map data, like OrganicMaps [1], to perform your calculations on the device. From a privacy perspective, you reveal only a coarse-grained notion of the area you’re interested in. As a "bonus", you get an offline maps app. You need to know a priori what areas you’ll need. For directions, that's usually fine, because I’m usually looking at local places, but sometimes I want to explore a random spot around the globe. Real-time transit and traffic-adaptive routing remain unaddressed.
2. Self-host your own mapping stack, as with Headway (I work on Headway). For the reasons above, it’s harder than hosting your own wiki, but I think it’s doable. It doesn’t currently support storing personal data (where you’ve been, favorite places, etc.), but adding that in a privacy conscious way isn’t unfathomable.
The entire planet's worth reverse geocoding data is ~120gb. The map tiles file for whole planet is also ~120gb, and they both are precompiled, so you don't need hundreds of gbs of RAM to run your local planet. It's easier than you probably think nowadays. Not mobile-size, but local server-size
I'd love it if it were easier than I think, because I spend a lot of time thinking about it! I host maps.earth, which is a planet sized deployment of Headway mapping stack (which I also maintain).
To first order, you're right on about the storage size of a vector tileset and an geocoding dataset based on OpenStreetMap. But Google maps is a lot more than that!
Headway uses Valhalla for most routing. A planet wide valhalla graph is about ~100gb of storage. It doesn't produce reasonable transit directions. Transit is an even tougher cookie.
OpenTripPlanner gives good transit routing, but it doesn't scale to planet-wide coverage. We've settled on a cluster of OTP nodes for select metro areas - each one being on the order of 5-10GB of RAM.
So, I'd say we have some of the pieces of a general purposes mapping tool that could replace Google Maps usage, which you could host yourself.
But we don't have satellite imagery, real time traffic data, global transit coverage, rich POI data (like accurate opening hours, photographs, reviews).
Do all people want all these features? Probably not, but a lot of people seem to want at least some of it and it's not obvious to me that they'll be quickly solved.
Compare that to encrypted email: if I’m sending you an encrypted message, the total data involved is minimal. To a first approximation, it’s just the message contents.
But if I want “Google Maps but private,” I first need access to an entire globe’s worth of data, on the order of terabytes. That’s a lot of storage for your (usually mobile) client, and a lot of bandwidth for whoever delivers it. And that data needs to be refreshed over time.
Typical mapping applications (like Google Maps) solve this with a combination of network services that answer your questions remotely (“Tell me what you’re searching for, and I’ll tell you where it is.”) and by tiling data so your client can request exactly what it needs, and no more, which is also a tell.
The privacy focused options I see are:
1. Pre-download all the map data, like OrganicMaps [1], to perform your calculations on the device. From a privacy perspective, you reveal only a coarse-grained notion of the area you’re interested in. As a "bonus", you get an offline maps app. You need to know a priori what areas you’ll need. For directions, that's usually fine, because I’m usually looking at local places, but sometimes I want to explore a random spot around the globe. Real-time transit and traffic-adaptive routing remain unaddressed.
2. Self-host your own mapping stack, as with Headway (I work on Headway). For the reasons above, it’s harder than hosting your own wiki, but I think it’s doable. It doesn’t currently support storing personal data (where you’ve been, favorite places, etc.), but adding that in a privacy conscious way isn’t unfathomable.
[1] https://organicmaps.app (though there are others)
[2] https://github.com/headwaymaps/headway (see a hosted demo at https://maps.earth)