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Comment by christiangenco | Hacker News Reader

Wow! I hadn't heard about this leak and used to live in downtown Dallas so when I saw the first few street names I thought "huh, Commerce, Griffin, and Main must be pretty common street names."

That "sci-fi overlay of street names" is really cool tech.

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It's also the only obvious answer for how to provide location information. Should street names be somewhere not overlaid near the street itself?

Don't know about Griffin, but Commerce and Main are pretty common in downtown cities. Commerce and Main is an intersection in downtown Houston.

I was genuinely impressed. Like, it makes sense that it exists given everything else we have now, but it has been a while since I saw a piece of software that works so well against real time video. All of a sudden, all that talk about augmented reality does not seem so far fetched.

It's actually not too difficult. The camera turret has incredibly precise GPS and knows exactly what angle it's at. With that, it's pretty straightforward to figure out where it's pointing at on the ground, grab the relevant map data, and overlay graphics.

Ahh, thank you! I was super curious how that was done.

I wouldn't call it "straightforward" but it is definitely computable. I worked on such a cartography-video overlay system about 10+ years ago, and you need at a minimum: precise GPS (as you pointed out), distance offset between GPS antenna and camera gimbal, precise aircraft attitude in all three axes, precise gimbal attitude, and a very good terrain model giving you altitudes of the land around the camera target. You also need to project your location, camera vector, and field of view polygon into a coordinate system that takes into account the curvature of the earth, because these aircraft are often many km from their targets. Very interesting project.

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