Things you find on Google Earth

[Xeque]

I'm not sure where to put this so I'll leave it to the mods. Also, apologies if it's been ppruned before.

Look at Stansted Airport (EGSS) on Google Earth and draw a line along the extended centreline of 23. Zoom in at the point where the line crosses the M11 and you will see an Easyjet B737 on final to 05 (2.3 miles to go).

OK. So what?

Go back to the runway and zoom in on the second exit for 23 and you will see not one but two Ryanair B737's exiting together.

What is happening here? Two aircraft - one exiting and one waiting to exit with a third aircraft arriving from the opposite direction :eek: The Easyjet is about a 45 seconds from touchdown.

Is it the exact moment when a runway direction change is taking place or do they sometime accept opposing arrivals at Stansted? If so, is it normal to leave so little time to clear the runway?

Also it seems evident that the second Ryanair landed very close behind the first, certainly well before the first aircraft had reached its intended exit.

The Easyjet on final has been on Google for more than a year to my knowledge so the incident happened at least that long ago. Also, I can't find any obvious breaks in the picture so I have to assume that it is taken from a single satellite image.

Any comments?

[oversteer]

:rolleyes: The 'image' is made up of multiple tiles taken at intervals. So aircraft moving around on the ground can appear on multiple tiles. It's not one big image.

[groundbum]

the latest version of google earth now draws the satellite imagery tiles and will tell you if you hover over the dot which satellite and when took the image...

G

[Diaz]

If it has the resolution for you to make out individual aircraft in terms of which airline they are- it is a picture taken from an aircraft flying overhead, not a a satellite- so obviously, it has taken the pictures in strips running in a different direction than the runway, so you are seeing pictures that could be hours or even days apart.

[The SSK]

Something that's been puzzling me - what's the big twin at the far end of the apron at Antwerp? I can only think of a CV580, but it has a very curious shape to the rear fuselage and horizontal stabiliser.

[Flap40]

It's an Andover.

[Xeque]

OK.

Oversteer - There is no need to be 'sarcastic' here. Diaz - I take your point but no-one ever did an aircraft overfly photo composit of Thailand where I live but the image of my house is good enough to show full details of my swimming pool.

If we are looking at 'tiled' images then why do we not see parked aircraft stacked one on top of another on the stands?

[HEATHROW DIRECTOR]

I was under the impression that Google pics were all satellite images??

As for the aircraft mentioned... How about if the two on the runway were simply taxying from one side of the airfield to the other? No problem there with the next lander at a couple of miles out..

There's a forum somewhere, which i becamke rapidly bored with, where there are dozen of such "sightings" listed for Google.

[Groundloop]

HD, a lot of the higher resolution images on Google are aerial photos. Look at the name of the image supplier at the bottom. Companies like Infoterra supply aerial photography. I know some satellite imagery is quite incredible these days but won't show the level of detail as those Stansted images - close but not close enough!

[Xeque]

HD

This is the image I'm talking about.

http://i150.photobucket.com/albums/s113/Xeque22/NewPicture.jpg

No-one moves aircraft around like that on an active runway. And in any case, both are showing flaps in landing configuration so they are certainly not manouvering from A to B.

If it was a duplicated image as suggested by others here then why isn't the aircraft on the taxiway in the bottom left hand corner duplicated also?

I accept that it is possible that the image of the arriving Easyjet and the movements on the ground at Stansted may be from two different timeframes. That is why I made the point that I'd looked for image breaks between the two but could find none.

Someone else mentioned that you can see the date/time stamps of the images used on Google but I don't think my version supports that. I would be happy to be proven wrong here if someone could show me how.

What isn't clear is why two aircraft are queued at the exit from 23. Basically that is the question I'm asking. The fact that a third aircraft is approaching from the opposite direction may well prove to be erroneous. I really hope so.

[Notso Fantastic]

I think the shadows of the aeroplanes look very slightly different, so I think there is a good chance the aeroplanes are from different images. And indeed the other aeroplane further along the taxiway has a different shadow altogether.

Isn't http://local.live.com, the Microsoft version of Google Earth, actually better? Certainly is for my area.

[MAN777]

Its simply a mosaic made up of consecutive digital images, the 737 is still moving and has covered a considerable distance between shots. If you were to put the image in photoshop and zoom in you would probably find the join between the frames.

[HEATHROW DIRECTOR]

Groundloop - OK, many thanks for that.

"No-one moves aircraft around like that on an active runway. "

Well I'm sorry to disillusion you, but it goes on all day all over the world! I've certainly done something similar at Heathrow many, many times with aircraft crossing or backtracking a runway. I accept your point about the configuration and the aircraft are obviously not re-positioning. However, they certainly didn't land either!!!!

[tcinbg]

I think you will find it is the same aircraft. Follow the link which is Microsoft VE, (one aircraft) then click on Google Maps in the top left hand corner and it appears as two aircraft.

http://www.flashearth.com/?lat=51.88132&lon=0.232007&z=15.7&r=0&src=msl

[Xeque]

Thanks everyone for the comments. I'm still not 100% convinced. It's the aircraft on the taxiway at the bottom of the picture that has me bothered. Maybe if Groundbum could tell me how to establish the date and time of the images it would help.
One thing puzzles me. I remember the original aerial photo survey that took place in the UK during the '80's. An aircraft flew a grid pattern at a constant altitude across the UK and established the first photo 'map'. Diaz and Groundloop mentioned current aerial photography. Is this still an on-going project and if so, who is funding it?
I, like HD, always believed that the Google Earth maps were generated by satellite imagery. The detail provided is not that bad. I already mentioned the detail that is visible of my home in Thailand where, I know, no aerial photo mapping has ever taken place.

[Bushfiva]

how to establish the date and time of the images it would help

10th September 2006.

[Chrisbowe82]

53°20'48.09"N 2°16'37.78"W

Hate to rain on your parade, but have a look at MAN specifically 23L
There are about 5 aircraft on the runway in the picture... Still think you've found something?

just go to Manchester airport, UK and look at 23L/05R

[HEATHROW DIRECTOR]

Chrisbowe82 - Blimey... they let Jenks loose in the tower again???

[The Flying Pram]

This (http://www.flashearth.com/?lat=52.363271&lon=4.712219&z=17.1&r=0&src=ggl) is at Schipol, and shows a 747? with only one wing, yet the shadow is a complete aircraft.

[TheChitterneFlyer]

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 :ugh:

[VAFFPAX]

I can confirm that Google uses a combination of air and satellite imagery. There are several incidents that The Register (http://www.theregister.co.uk/) 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.

[IRRenewal]

This is at Schipol, and shows a 747? with only one wing, yet the shadow is a complete aircraft.

And when you zoom out enough the whole runway disappears.

[The Flying Pram]

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 :ugh:

Yes, I did realise that - just testing! Honest....

And when you zoom out enough the whole runway disappears.

I hadn't spotted that, It happens in both Google and Microsoft. Presumably the low resolution shots from satellites are much older than the close up ones. When was the new remote runway built?

[wingisland]

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

[Groundloop]

"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.

wingisland, don't be too dismissive of commercial satellite imagery. The highest resolution available is a pixel size of 0.5m in black and white or 0.6m in colour. You don't reposition satellites, they orbit continuously and cover the whole globe in just over two weeks. With this repeat rate most areas will get cloud free coverage at some time.

0.5m sample can be viewed here:-

http://www.digitalglobe.com/downloads/featured_images/sydney_dec31_2007_dgwm.jpg

0.6m colour here:-

http://www.digitalglobe.com/downloads/featured_images/las_vegas_midstrip_oct14_2005_dgwm.jpg

Not bad from orbit!

[wingisland]

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?

[Rainboe]

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 (http://www.metoffice.gov.uk/satpics/latest_IR.html) 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).

[Groundloop]

Also you have two types of satelite, Geocentric and Geostationary,

Never heard the term Geocentric before to describe a satellite - Geostationary yes. You seem to use geocentric to describe a satellite that "goes round the Earth". As Rainboe mentions geostationary satellites orbit at about 24,000 miles because, only at that altitude, do they orbit the earth in the same time the earth rotates so they remain over the same point, which HAS to be on the equator.

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.

I think you will find that Google Earth uses vast numbers of these images from DigitalGlobe.

[wingisland]

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!

[Groundloop]

But I still standby the satelites cant yet do the quality of aerial photography, otherwise i'd be out of a job!

True, they can't. But for a lot of applications the high resolution satellite image is now good enough. Certainly since these satellites became operational the demand for aerial photography has reduced significantly around the world.