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Comment by toomuchtodo | Hacker News Reader

> I'm also not quite sure on why exactly it is so complex to distinguish between objects (including vehicles) on the road and ones above/next to it.

Because radar does not have the same resolution as LIDAR.

EDIT: Phased array radar and cheap stationary LIDAR should get under $100 in ~5 years, at which point this whole argument will be moot. Hacks in the meantime!

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What does the world look like in radar? Are there any visualizations available?

Could multiple radar emitters and receivers be used to create a phased array and improve resolution?

Here is the resolution calculation for aircraft radar (with respective example of signature - aka image )

http://www.radartutorial.eu/01.basics/Range%20Resolution.en....

For angular resolution: http://www.radartutorial.eu/01.basics/Angular%20Resolution.e...

> What does the world look like in radar?

Depends on the radar system. Some are distance only without direction. Some are 1D (a line, usually horizontal) and some are 2D. Many objects are partially opaque, which is confusing. Resolution is very poor compared an optical device of the same size.

> Could multiple radar emitters and receivers be used to create a phased array and improve resolution?

Yes. However, this is currently bulky and expensive (in dollars and in compute power). Thankfully, it looks like capitalism is coming in to the rescue here and miniaturizing the everloving shit out of complex radar arrays for human interface tech. This should be usable for vehicles as well.

All the automotive radars are phased array devices, and have been since the Eaton VORAD of the late 1990s. No moving parts. They're usually 1D scan (horizontal) only, although 2-axis scanned automotive devices exist.

If you're cresting a hill or rounding a curve, passing under a bridge, etc., static objects in the visual field are translating in front of the vehicle and are not easy to distinguish from slow moving vehicles. With simple sensors, there isn't enough information to decide that these blips are on a collision course or not.

The Florida situation was the easiest set of circumstances for machine vision to handle and it still failed. More complex, dense road systems with real terrain are much harder to handle. This radar system will still get someone killed.

The driver is still the final authority. Pay attention and in most cases, if you die, it won't be your fault.

Is LiDAR worthwhile despite rain and snow detection? Can that be ignored in software?

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