I'm guessing the "AI" was used in the geometry mapping from the sat data they used for their region maps.

Microsoft's Bing maps uses a huge amount of aerial orthophotos as well, not just satellite. Also aerial lidar for DEMs vs satellite radar data (the old srtm 1/3 for us48 states, etc).

I was just going by the trailer, which I'd imagine the Wikipedia page is citing, that references the azure AI and satellite data towards the beginning of the video.

My dream feature would be weather based on live meterological inputs.

You can have that right now for both X-Plane and Prepar3d with a very well made addon called Active Sky by Hifi Simulation Technologies.

Haven't they supported that for ages? I thought even FS2002 had that

FS2004 was the first to feature live weather

FlightGear has that, and is open-source.

https://www.flightgear.org/

I see! I was hoping it would have meant realistic auto generated air traffic :)

Artificial Intelligence could be used for a lot of things, like:

weather generation

ground handling at airports

random bird strikes

controlling in-game aircraft and their routes

Realistic ATC that understands what you say (think Cortana) and responds intelligently.

In the trailer, I saw multiple planes flying alongside. I was wondering whether this meant multiplayer (no idea if this is common in flight sims, they're a genre I still want to get started in), but it could also be a computer that flies alongside?

Azure AI is Microsoft's artificial intelligence platform in the the cloud , running on Microsoft's Azure cloud platform. I am guessing they will be using a cloud based AI service to provide AI features in the game.

Nothing

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