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Comment by notjulianjaynes | Hacker News Reader

Slightly off topic, but thanks to your first link I was just doing some satellite image sightseeing of Wuhan and noticed that on Google maps the streets are offset about 3 blocks east of where they should be.

It's fairly obvious here [1] where the curved road extends out into a lake.

Not saying this means anything, just found it amusing.

1. https://maps.app.goo.gl/reVDkMAhfMRbv1uJ8

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It's fairly well-known [0] that China messes with maps data and forces Google to do so.

[0]: https://en.wikipedia.org/wiki/Restrictions_on_geographic_dat...

Is this similar to how the US used to mandate that civilian use of GPS was off by a certain amount?

Yes, it's ostensibly still for defense purposes in China

A bit different. The GPS restriction was to prevent GPS on a device moving over 400 mph (I think that's roughly the speed?), and to limit accuracy to within a few meters rather than a few centimeters. The restrictions were intended to prevent the use of civilian GPS systems in precision missiles.

Not a lot of civilian uses require anywhere near that speed or accuracy.

It's a lot harder to justify grossly inaccurate geographic data as not hurting civilian uses.

you're referring to the CoCom Limits on GPS receives, which limits functionality when the device is moving faster than 1,900 km/h aka 1,200 mph) and/or at an altitude higher than 18,000 m (59,000 ft), so you can't build a home made ICBM with it. Technically it's supposed to be and and not or, and high altitude amateur aerial ballonists tend to hit that flight ceiling, and so have a list of chipsets they can use in their balloons that don't stop working when they get too high.

https://en.m.wikipedia.org/wiki/Coordinating_Committee_for_M...

I never understood how this works, at least effectively. Isn’t this just a device DRM? If you can build an ICBM you can probably hack a gps receiver, or build an unlocked one, no? If that encryption key is in every gps device, surely it must be available on eg darknet. And thus you could use existing gps infrastructure (ie avoid the expensive part of launching your own satellites). What am I missing?

There's no encryption, it's just a limit in the firmware.

What am I missing?

The collective intelligence --- or lack thereof --- of the bureaucracies that come up with these laws.

It wasn't a pre-set error, rather each satellite was originally configured to broadcast a low-precision coarse signal and a high-precision signal and the high-precision signal could only be decoded using an encryption key. They later released the encryption key when civilian applications took off.

iirc there still are several signals broadcast, a rare public high precision signal (for land surveyors), a high precision stream (military) and a high enough precision stream (public navigation)

Sort of. It uses a pre-defined transformation that doesn't interfere with street navigation. If you're on a street it will precisely reflect that value as well as any other GPS. But it makes it difficult to perform purely GPS-based instrument navigation, which in theory makes it harder to conduct eg missile strikes.

No, the US one is basically error(like noise) injection and has been disabled: https://www.gps.gov/systems/gps/modernization/sa/

The Chinese one is effectively a warped coordinate system, see GCJ02: https://en.m.wikipedia.org/wiki/Restrictions_on_geographic_d...

Huh, I guess I wasn't aware of this previously. Figured it was a bug or something.

Considering the satellite imagery exists this seems silly. Glad I didn't drive into a lake!

I just want to add to this that when I first heard about this virus I searched the WIV on Google Maps. I believe that was 14 January 2020. When I searched it again a few weeks later, the location on Google Maps had changed.

I have no screenshots of this, but I did find it quite odd at the time.

Addresses of things change on Google maps. They fix problems and find issues and it's entirely possible that an address changing means something was updated. Or there's an international address conspiracy that Google is part of, you'll have to decide for yourself!

This change of address is initated by an authority of that region or owner of that business. What exactly is your motivation is spreading FUD on this matter?

I don't think it's fine. When I worked at Google, we got updated address information for businesses periodically and we had an official process that applied updates to the data we had stored. It was actually a colossal pain in the butt. I could see that still being the way that addresses can get updated?

omniglottal, I wish you'd comment further about address info changing. Like the other responder to you, third parties can ask to update address info. It's absolutely not conspiratorial. Can we agree it's not a conspiracy?

You don't have to be a business owner to change the location of a business on Google Maps. They rely on the general public to correct inaccuracies - I've done this a few times for certain locations near me. Presumably they use some kind of scoring system to determine whether the request to make the change is valid.

It's fine on Apple Maps.

That's Chinese map data obfuscation. The idea is to make it marginally harder for an adversary to target missiles using public map data.

Which is useless in this day. I was in China last week and Google Map’s street layer was aligned correctly to where I was, but the satellite imagery was not.

This demonstrates that Google already knows the correct coordinates of street in China, including those of an airport finished in 2021. For some reason they have spent no time manually aligning the imagery.

Coordinates on the globe are constant whether China likes it or not, my only guess is that Google doesn’t want to spend time fixing data in a country that blocks them entirely.

The wiki above explains it. Technically they are supposed to purchase a shift algorithm.

Google is doing no business in China, so they don’t “have to.” They could easily bypass that by internally mapping the imagery to the vectors, they have thousands of developers who could do this.

Even if they had to buy it, they’re not buying it because again they don’t do business there.

Who does Google buy map data within China from?

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