
StreetLearn: Learning to navigate in cities without a map - espadrine
https://sites.google.com/view/streetlearn
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cs702
The agent learns to navigate entire cities by exploring them on the ground (it
sees only Google Street View photos), _without any map or location data_.

The human analogy would be to ask _you_ to learn to navigate a new city (whose
language you don't understand) without ever using a map or location data,
simply by driving around and looking out of the car. You will drive around
and, as you see different street scenes, you will gradually build a "mental
model of the city" that allows you to navigate it.

That's essentially what the agent does.

Once trained, when the agent is asked to go to a particular location, it knows
how to get there, despite never having seen a map of the city.

Impressive.

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ForHackernews
Oh, I thought this was going to be a technique for humans to find their way.
We need some other word for "learning" that specifies "training a computer
model".

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JorgeGT
My two tricks: satellite dishes point south†, more or less, and Christian
churches are usually built with the altar pointing east.

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†In the northern hemisphere.

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madcaptenor
Satellite dishes point south in the _northern_ hemisphere, right? Since they
orbit over the equator.

I've never found this practically useful, because the one city where I've
wandered a lot and saw a lot of satellite dishes is Philadelphia, which has a
grid layout. But I do recall noticing it.

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JorgeGT
Yes, of course! Sorry for that. Being European I sometimes envy not only those
neat grid layouts, but also the numbered streets, because from the numbering
you can infer the position of the target. But "Saint Joseph's street" could be
at the next corner or on the other side of town, you cannot know...

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mopeloi
So, is this picking up on large landmarks which are visible in StreetView? Sun
position in imagery? In Manhattan can it see a sign reading W 53rd St and know
whether to go north or south to its destination? The paper suggests that there
are learned landmarks, but doesn't talk about street signs at all. As a New
Yorker, that would be the first method I would use to reach a destination.

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curiousgal
It's a neural network so chances are, we'll never know _how_ it came up with
it's decision. For CNNs we can look at the output of each layers to get a hint
but the more diverse the architecture is (such as in this example) the harder
that becomes.

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speps
It went backwards all the way in London. I wonder if it didn't know which side
of the road it should have been on... Might have helped going through some one
way streets.

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mxwsn
That's just due to Google maps street view - the original images happened to
be recorded in the other direction. You'd have the same 50/50 chance on any
two way road.

