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Why is the Gaza Strip blurry on Google Maps?

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Re: Why is the Gaza Strip blurry on Google Maps?

#271

Post by beerandt »

ComputerGuru wrote: post #211
kzrdude wrote: post #187

It's usually called satellite imagery, but isn't most of the high-resolution, closest photos actually aerial imagery, not from satellites? In that case I would understand if there isn't that much coverage.

No; at least per the providers, actual low-orbit satellite imagery is available to the (paying) public at 50cm resolution.

It's available, but by far the actual high quality (This is usually a result of the data set already being paid for, either via the local assessor's office or the USDA. This doesn't mean it's always available for free, but that the economics means it's usually available for less than the actual cost.

Re: Why is the Gaza Strip blurry on Google Maps?

#272

Post by londons_explore »

yborg wrote: post #205
tomerv wrote: post #177

Earlier quoted context omitted.

Interesting to note that the removal of selective availability enabled the creation of Geocaching ( https://en.wikipedia.org/wiki/Geocaching#History ).

It also enabled the modern mobile navigation industry. I was working on automotive navigation systems in the early 90s and SA was a killer for the product, options were various dead-reckoning and inertial sensors or differential GPS, both of which ended up being cost-prohibitive. But you can't do usable route guidance with a 100m CEP in an urban area.

With modern high powered CPU's, more detailed maps, and particle filters (which require all that cpu), dead reckoning has become much more viable.

I suspect you could go hours driving round a city with the GPS and WiFi location turned off before losing your position - simple wheel speed, gyro and compass is sufficient for most stuff.

Re: Why is the Gaza Strip blurry on Google Maps?

#273

Post by askvictor »

tomerv wrote: post #177
jrochkind1 wrote: post #113

Earlier quoted context omitted.

My memory says that US government GPS at one point intentionally introduced reduction in accuracy/resolution as well, but they stopped, which was part of what led to the commercial GPS revolution (along with cheaper tech of course). Let's see... Wikipedia seems to confirm: > During the 1990s, GPS quality was degraded by the United States government in a program called "Selective Availability"; this was discontinued o…

Interesting to note that the removal of selective availability enabled the creation of Geocaching ( https://en.wikipedia.org/wiki/Geocaching#History ).

There were already workarounds in place before they switched off SA - the introduced error was consistent within a given area, so provided you had a fixed location that broadcast its coordinates, you could correct for the error. I believe there were products and possibly even standards that did all of this; would have been even easier in today's world of mobile internet. I have suspicions that this was a large reason for disabling SA - your enemy can work around it, so it's not much use, but if you get your enemy hooked on it without the work-around, you can turn SA back on in a war situation.

Re: Why is the Gaza Strip blurry on Google Maps?

#274

Post by liversage »

jrochkind1 wrote: post #113
squeaky-clean wrote: post #97

Not really related to the article at hand, but I've been on a bit of a Google Maps binge the past couple weeks. I learned a few interesting facts, blurry Israel being one of them. Another strange thing I found that might not be super well known (I didn't know about it) is that all GPS data in China is offset by a nonlinear psuedo-random amount. If you turn on the satellite view in Google Maps and look at various citi…

My memory says that US government GPS at one point intentionally introduced reduction in accuracy/resolution as well, but they stopped, which was part of what led to the commercial GPS revolution (along with cheaper tech of course). Let's see... Wikipedia seems to confirm: > During the 1990s, GPS quality was degraded by the United States government in a program called "Selective Availability"; this was discontinued o…

I've heard that just before Operation Desert Storm began in 1991 the reduced accuracy that affected civil GPS was temporarily turned off. This was a result of not being able to procure enough military grade GPS devices for army vehicles etc. If this is true it may also have had an effect on the decision to completely turn it off.

Re: Why is the Gaza Strip blurry on Google Maps?

#275

Post by Cd00d »

deadalus wrote: post #5

Is it possible to have real-time live-feed of the entire planet? If cost isn't an issue, would something like that be possible?

Think of each pixel. If you want 1m resolution, you need at least one pixel for every meter of the planet. And, satellites can't be told to stay over land only. So, how many satellites do you need in your constellation to keep a 1s refresh time?

The earth is 200 million miles^2 surface area.

So, no. I sorta remember 4 day refresh at 3m resolution was the "wish I could get to" goal.

Re: Why is the Gaza Strip blurry on Google Maps?

#276

Post by [deleted] »

stormbrew wrote: post #240
sequoia wrote: post #231

Earlier quoted context omitted.

Here is a single reference: https://www.middleeastobserver.org/2016/07/12/pcbs-reports-g... "Do you generally call things out as being untrustworthy for claiming that the top 5% is among the highest in a rank?" The reason I consider this claim "misleading" is that I never see the "one of the most densely populated..." phrase on stories about Paris, Kathmandu, Seoul or any of the hundreds of more densely populated are…

Are Paris, Kathmandu, Seol, or Hoboken under blockade by a government that claims their land but makes the people on that land stateless, and also periodically bombs their urban infrastructure? It's possible that the density of gaza is in some way relevant to the current events taking place there in a way that it might not be for the other places you've listed.

[deleted]

Re: Why is the Gaza Strip blurry on Google Maps?

#278

Post by newman8r »

csteubs wrote: post #172
caymanjim wrote: post #34

Earlier quoted context omitted.

The short answer is no. High-resolution imagery comes from low-orbit satellites, which make a complete orbit about every two hours, and image long, narrow strips with each pass, taking days to image the whole planet. There are many of these satellites: commercial, non-military (publicly-accessible) governmental, and governmental (secret), of varying resolutions. These are also supplemented by aerial (plane) imagery.…

I'm the founder of a company working to solve this exact problem. Revisit rate of Planet's 200+ Dove satellites are quite good (multiple/day) but are comparatively low-res compared to their Rapideye satellites, of which there are fewer. There are a slew of others (Maxar is the next biggest name that comes to mind) but the thesis is low earth orbit is getting crowded, satellites are incredibly expensive even with off-…

Are you talking about passengers taking photos/video out of windows?

Re: Why is the Gaza Strip blurry on Google Maps?

#279

Post by woodpanel »

sequoia wrote: post #242
jcranmer wrote: post #142

Earlier quoted context omitted.

You're probably missing this listing: https://en.wikipedia.org/wiki/List_of_countries_and_dependen... Where Gaza listed as its own country, it would be one of the densest, since it's basically a city and its urban sprawl and nothing more (like the other densest entries on the list). Of course, Gaza is itself arguably only part of Palestine, but the West Bank itself is pretty dense (see how high Palestine ranks on tha…

Looking at the country list, I see Israel is the #5 most densely populated country in the world. And Bnei Brak is the #5 most densely populated city, far more densely populated than Gaza. Bnei Brak was hit by rockets this week. Can you link me to some articles that refer to "Hamas firing rockets on Bnei Brak, one of the most densely populated cities in the world"? Or "on israel, one of the most densely populated coun…

Since this question revolves around words and their effect…

"most populated" > "crammed" > "jailed" > "the new warsaw ghetto"

there must be a word that describes your question of why:

The word you're looking for also describes what's enabling the cognitive dissonance of putting Gaza in the same category as a Singapur, a Tokio or Hong Kong without blinking: Economic powerhouses that draw talent from developing and developed nations worldwide vs. a town with an economy that only consists of NGOs, the Hamas and UN-Organizations (The wage gap between ordinary gaza citizens and those working for the state is 50%).

But instead of owning that word, it's easier to just keep uttering "Israel is bombing one of the most densely populated places in the world".

Re: Why is the Gaza Strip blurry on Google Maps?

#280

Post by URSpider94 »

jrochkind1 wrote: post #113
squeaky-clean wrote: post #97

Not really related to the article at hand, but I've been on a bit of a Google Maps binge the past couple weeks. I learned a few interesting facts, blurry Israel being one of them. Another strange thing I found that might not be super well known (I didn't know about it) is that all GPS data in China is offset by a nonlinear psuedo-random amount. If you turn on the satellite view in Google Maps and look at various citi…

My memory says that US government GPS at one point intentionally introduced reduction in accuracy/resolution as well, but they stopped, which was part of what led to the commercial GPS revolution (along with cheaper tech of course). Let's see... Wikipedia seems to confirm: > During the 1990s, GPS quality was degraded by the United States government in a program called "Selective Availability"; this was discontinued o…

This is different but related. China has no ability to influence GPS accuracy within its borders. What they do is manipulate all of the authoritative maps available so that GPS coordinates won’t map cleanly to the digital waypoints in the map. The GPS locations are very precise, they are just off by as much as a quarter mile in varying directions depending on where in the county you are.
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