Things you find on Google Earth
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I can confirm that Google uses a combination of air and satellite imagery. There are several incidents that The Register calls "cloaking devices", where one tile may contain part of a plane or train, and the neighbouring tile does not, leading to a 'cloaking' or 'decloaking' of said vehicle.
So yes, the tiles at Stansted can display such similar occurrences. While the planes at the north-eastern most end of the runway might be queuing, but the 'two' planes exiting the runway must be the same plane.
The photo of the Easyjet on approach is definitely a different series.
S.
So yes, the tiles at Stansted can display such similar occurrences. While the planes at the north-eastern most end of the runway might be queuing, but the 'two' planes exiting the runway must be the same plane.
The photo of the Easyjet on approach is definitely a different series.
S.
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This is at Schipol, and shows a 747? with only one wing, yet the shadow is a complete aircraft.
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Go to the north of the one-winged B747 and you'll see the line of the 'stitched image' by the difference in colour of the fields etc. Hence, the one-winged B747 was right on the join of the image... yet the shadow remains intact by virtue of the position of the sun. Simple really isn't it 
And when you zoom out enough the whole runway disappears.
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I've been doing aerial survey for 6months, specifically pictometry, the technical term for taking pretty pictures out of an aircraft!
You'll notice as you zoom in the image all of a sudden improves dramatically, that's the change from satellite to aircraft.
"But surely you have satellites which have excellent resolution, why not just use those"
Well from what I understand there is two problems with that, firstly certainly in the civilian world you don't have satellites with that ability, also you'd be repositioning a satellite to specific points all over the world, a costly and lengthy process for all of the world in that resolution, also you could have a satellite sat over Paris waiting for no cloud when London is clear, an aircraft is quicker and more effective at repositioning quickly to the clear sky.
The way pictometry works is some clever people in an office figure out how your going to fly a specific targets, mainly how the lines are going to be positioned and spaced, then as the pilot you go to that area and fly racetrack patterns (or mowing the lawn, whichever analogy you prefer!) covering the whole area. I've seen photos where the target happened to be over a railway track, and it just happened to coincided with the aircraft taking its picture of the track at the same point a train travelled along it, result was a 5 mile long train! There is also a great deal of overlap on the photos, so put those two factors in and what your seeing at Stansted almost certainly all wasn't taken at the same time. Also some targets don't get done in one day, i've taken weeks on some targets, maybe flying a couple of lines a day.
You also get two sorts of aerial photography, one where the aircraft is 30,000ft up doing a half decent map so everyone has their house taken with better resolution than a satellite can provide (probably why you can see your house) then another aircraft at lower lever (3000-6000) does the really high resolution mapping for major towns and cities.
But where the money comes from this, I have no idea!
Hope that helps
You'll notice as you zoom in the image all of a sudden improves dramatically, that's the change from satellite to aircraft.
"But surely you have satellites which have excellent resolution, why not just use those"
Well from what I understand there is two problems with that, firstly certainly in the civilian world you don't have satellites with that ability, also you'd be repositioning a satellite to specific points all over the world, a costly and lengthy process for all of the world in that resolution, also you could have a satellite sat over Paris waiting for no cloud when London is clear, an aircraft is quicker and more effective at repositioning quickly to the clear sky.
The way pictometry works is some clever people in an office figure out how your going to fly a specific targets, mainly how the lines are going to be positioned and spaced, then as the pilot you go to that area and fly racetrack patterns (or mowing the lawn, whichever analogy you prefer!) covering the whole area. I've seen photos where the target happened to be over a railway track, and it just happened to coincided with the aircraft taking its picture of the track at the same point a train travelled along it, result was a 5 mile long train! There is also a great deal of overlap on the photos, so put those two factors in and what your seeing at Stansted almost certainly all wasn't taken at the same time. Also some targets don't get done in one day, i've taken weeks on some targets, maybe flying a couple of lines a day.
You also get two sorts of aerial photography, one where the aircraft is 30,000ft up doing a half decent map so everyone has their house taken with better resolution than a satellite can provide (probably why you can see your house) then another aircraft at lower lever (3000-6000) does the really high resolution mapping for major towns and cities.
But where the money comes from this, I have no idea!
Hope that helps
"But surely you have satellites which have excellent resolution, why not just use those"
Well from what I understand there is two problems with that, firstly certainly in the civilian world you don't have satellites with that ability, also you'd be repositioning a satellite to specific points all over the world, a costly and lengthy process for all of the world in that resolution, also you could have a satellite sat over Paris waiting for no cloud when London is clear, an aircraft is quicker and more effective at repositioning quickly to the clear sky.
Well from what I understand there is two problems with that, firstly certainly in the civilian world you don't have satellites with that ability, also you'd be repositioning a satellite to specific points all over the world, a costly and lengthy process for all of the world in that resolution, also you could have a satellite sat over Paris waiting for no cloud when London is clear, an aircraft is quicker and more effective at repositioning quickly to the clear sky.
0.5m sample can be viewed here:-
http://www.digitalglobe.com/download..._2007_dgwm.jpg
0.6m colour here:-
http://www.digitalglobe.com/download..._2005_dgwm.jpg
Not bad from orbit!
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I have to admit, the information about satelites was what my previous boss said to me!
I suspect that even though (as your images pointed out very well!) satelite imagery is no doubt very good, it still isn't to the level of quality companies like google earth are looking for.
If the satelite image is 1pxl = 0.5M then the cameras we were using at 1pxl = 1inch is obviously going to be superior. I'm sure there are satelites out there with that capability, probably military grade, and I have no doubt that they will be available to civilian use in the not so distant future.
Also you have two types of satelite, Geocentric and Geostationary, my assumption was you would use Geostationary to do high level photographic mapping, surely any Geocentric camera which can go round the earth in two weeks wont have the ability to produce quality detailed low level imagery?
I suspect that even though (as your images pointed out very well!) satelite imagery is no doubt very good, it still isn't to the level of quality companies like google earth are looking for.
If the satelite image is 1pxl = 0.5M then the cameras we were using at 1pxl = 1inch is obviously going to be superior. I'm sure there are satelites out there with that capability, probably military grade, and I have no doubt that they will be available to civilian use in the not so distant future.
Also you have two types of satelite, Geocentric and Geostationary, my assumption was you would use Geostationary to do high level photographic mapping, surely any Geocentric camera which can go round the earth in two weeks wont have the ability to produce quality detailed low level imagery?
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Geostationary satellites orbit about 24,000 miles out, and hovering over a small area of the Earth's surface in Equatorial regions, aren't much good from that range taking close up photos vertically overhead! Their use is weather region photos and broadcast transmissions. For the higher latitudes, they are no use at all for Google Earth. The lower orbit satellites cover a far wider latitude band (depending on the inclination of the orbit) with a far lower altitude and can take far better resolution pictures with a proper overhead view. This geostationary shot of Europe Met Office: Europe: Infrared satellite imagery is an example, slightly deformed image to show corrected scale from top to bottom (ie boost Iceland a bit because it is further from the camera than Spain).
Also you have two types of satelite, Geocentric and Geostationary,
The satellites used to produce the images I linked to orbit at between 450 and 500 kms - a lot lower than geostationary satellites.
it still isn't to the level of quality companies like google earth are looking for.
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Well, you learn something new everday! I didnt realise that the stationary satelites had to be so high but as your post points out it makes perfect sense.
I suppose the other advantage would be it could take a wider angle shot, less need for the stitching and overlaying of images, and less posts on PPRuNe like this current thread!
But I still standby the satelites cant yet do the quality of aerial photography, otherwise i'd be out of a job!
I suppose the other advantage would be it could take a wider angle shot, less need for the stitching and overlaying of images, and less posts on PPRuNe like this current thread!
But I still standby the satelites cant yet do the quality of aerial photography, otherwise i'd be out of a job!
But I still standby the satelites cant yet do the quality of aerial photography, otherwise i'd be out of a job!
