rams it
Join Date: Oct 2004
Location: Seattle
|
How exactly can it take aerial photos of the Pacific Northwest, for example, without any clouds?
|
quote |
BANNED
I am worthless beyond hope. Join Date: May 2004
Location: Inner Swabia. If you have to ask twice, don't.
|
It only uses photos from clear days...
|
quote |
rams it
Join Date: Oct 2004
Location: Seattle
|
|
quote |
‽
|
|
quote |
BANNED
I am worthless beyond hope. Join Date: May 2004
Location: Inner Swabia. If you have to ask twice, don't.
|
Quote:
They probably use the most recent set of data... which are collected by people who decide when to fly (most likely on clear days), but as chucker noted sometimes the weather is a bitch... |
|
quote |
Space Pirate
Join Date: May 2004
Location: Atlanta
|
Yeah... just in case you don't know (assuming you do), the photos aren't in real-time. They're not often even in the same five year span.
|
quote |
Environmental Bloodhound
|
Simple answer: Magic.
|
quote |
Selfish Heathen
Join Date: May 2004
Location: Zone of Pain
|
Better answer: Gnomes.
1. Take satellite photos around the world. 2. ??? 3. Profit! |
quote |
rams it
Join Date: Oct 2004
Location: Seattle
|
Quote:
Someone mentioned flying though, so are these pictures from a plane? You had me at asl ....... |
|
quote |
Space Pirate
Join Date: May 2004
Location: Atlanta
|
Yes, they're not from satellites.
THOSE are sweet, sweet machines that require at least a J25. |
quote |
Veteran Member
Join Date: Feb 2006
Location: Arizona
|
there planes?
|
quote |
BANNED
I am worthless beyond hope. Join Date: Jul 2004
Location: Washington, DC
|
They're awfully high up to be taken from aircraft, considering that you can see aircraft in some areas.
|
quote |
Member
|
Definetly satelite images, you can see the source of the image in the google earth window. One of them is http://www.terrametrics.com/ and you can read where the source images come from.
The images of the Oceans are sourced directly from NASA. They source mapping data for the roads and buildings from Europa technologies, and from Navteq. |
quote |
BANNED
I am worthless beyond hope. Join Date: Jul 2004
Location: Washington, DC
|
Users are now able to "build" their own buildings, too, and submit them to Google.
|
quote |
Veteran Member
Join Date: Jun 2005
Location: State of Flux
|
|
quote |
hustlin
Join Date: May 2004
|
It's a combination both satellite imagery and super-high resolution aerial photography.
|
quote |
Veteran Member
Join Date: Jun 2004
Location: Portlandia
|
|
quote |
Veteran Member
Join Date: May 2005
Location: Paris, France
|
Quote:
It's a fabulous resource. I never tire of "exploring" world cities and remote little islands. |
|
quote |
Veteran Member
Join Date: May 2004
Location: Clayton, NC
|
Number 2, obviously: Go back in time and create a best-of-class, easy to use, powerful, Internet search engine and use the photos to make a subsection which shows maps, etc. then simply Go Public and continue to step 3.
Ugh. |
quote |
Space Pirate
Join Date: May 2004
Location: Atlanta
|
|
quote |
Veteran Member
Join Date: May 2004
|
Almost, but not quite:
Regarding the KH (Keyhole) US surveillance satellites (from here): "The black and white images are used by the military and civilian communities. Many of the details about this class of satellites remain classified, but it is known that there are several of these overhead at any given time. They have an imaging resolution of 5-6 inches, which means they can see something 5 inches or larger on the ground. These satellites probably can't read your house number, but they can tell whether there is a bike parked in your driveway." And remember, that's just the public info. The actual specs are probably much better. *lol* Check out the name for KH-10. Now we know why Dorian seemingly pulls information out of thin air... http://en.wikipedia.org/wiki/Spy_satellite |
quote |
Space Pirate
Join Date: May 2004
Location: Atlanta
|
I can't believe it took me this long to post a link to the article on How Google Earth Works at HowStuffWorks.com.
Sheesh. |
quote |
Veteran Member
Join Date: May 2005
Location: Paris, France
|
True, I should have qualified that statement to exclude spy satellites, which obviously offer much higher resolution than the commercial satellites in operation. which to the best of my knowledge are incapable of resolving objects less that a few metres across.
Resolution is a much misunderstood concept anyway (ask ten Leica fans to define it and you'll get at least five different answers!). A much better method (and indeed the primary scientific method) for describing the quality of an optical system is the Modulation Transfer Function (MTF), which is simply a description of the spatial frequency response of the lens system. So we can say that a lens delivers a certain contrast ratio (in percent) at a given frequency (usually line pairs per mm at the image plane). Quote:
But the contrast ratio of any lens drops as spatial frequency increases, so by simply choosing an object with higher contrast in the first place, the resolution is increased (this is why resolution is so useless for describing lens performance). For this reason resolution is often tested at a particularly high object contrast ratio, usually 1000:1. But a person walking down the street, viewed from a satellite's position in space, is far less than 1000 times brighter or darker than the street. So it's not accurate to say that a satellite that can just about detect an object 5 inches across against a uniform background (representing the object as a blur of just discernable contrast) actually has a resolution of 5 inches. When people think "wow, 5 inches!" they might imagine clear photos of their small dog sleeping in the garden. In reality such a dog would not be remotely identifiable as a dog. In fact, it's very possible that the dog would not even appear as a smudge on the photo, because for all we know they might mean a 5-inch object with a contrast ratio in excess of 1000000:1 (e.g. a spotlight shining upwards) rather than a dog on grass with a contrast ratio of perhaps 10:1. … engrossed in such factional acts as dreaming different dreams. |
|
quote |
hustlin
Join Date: May 2004
|
Quote:
|
|
quote |
BANNED
I am worthless beyond hope. Join Date: May 2004
Location: Inner Swabia. If you have to ask twice, don't.
|
More to the point...
The spy sattelites can see paterns of objects placed five inches apart, but not say two inches apart... |
quote |
Posting Rules | Navigation |
|
Thread Tools | |
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Google Spreadsheets | kieran | Third-Party Products | 17 | 2006-06-07 17:46 |
'Farmer's huge arse pops up on Google Earth' | Hassan i Sabbah | AppleOutsider | 2 | 2006-06-04 12:28 |
What have you found with Google Earth | alcimedes | AppleOutsider | 12 | 2006-04-07 23:04 |
New version of Google Earth now runs on Mac OS 10.3.9 | Dorian Gray | Third-Party Products | 4 | 2006-02-21 22:27 |
A Safe and Happy 4th to my American brethren. | Moogs | AppleOutsider | 6 | 2004-07-04 17:01 |