rex

You may have seen this before on any of various photography websites or collections labeled as Google Earth gallery...

http://preview.tinyurl.com/FrankfurtAirport

How can this be... three big jets, taking off like geese in a line, less than 2000 feet apart?

Wink... if you know the answer. I'll post it here tomorrow.

Best wishes,

Rex

rex

no nibble of interest from any one? really? no one got their curiosity piqued?

RonDace

Are they taking multiple photos to increase the resolution by combining the individual frames?

adrienne

Hi Rex,

Well I'm curious but I have no idea. How do you know the planes are 2,000 feet apart?

capxxx

One is a shadow and one is parked on the ground. What do I win?

rex

Ron gets the prize (or at least that's my understanding); presumably, the sat photos minimmize clouds and other interference by taking multiple photos just one or two seconds apart - - so, the "three" planes are in fact, the same plane.

>

There is a scale in the lower lefthand corner.

adrienne

Well I knew the 3 black planes were shadows!

So you're saying that there are three photos superimposed to show three white planes?

rex

Yes, I believe that they add the three photos (taken a second or two apart) together. And so, the (positive or white) image of the plane (but also its shadow) appears to be in three different places.

Echnaton

There are three images of the same white plane and three images of its shadow.

However, there are not three images of cars or trucks on the autobahn.

Strange, strange.

Did someone play a trick? Sometimes, the programmers make such jokes.

Cowboy1968

If they work with several photos pasted into one, I'd assume that some software looks for items that have only moved a little like the cars or trucks and deducts those from exposure 2 and 3. Since the airplane moved faster, the system might have failed and regarded it as 3 different objects.

rex

Actually, if you look closely on the highway, you can find a few distinctive looking vehicles that ARE visible "twice".

I agree that there probably is software designed to remove duplicated moving objects, though there are probably human operators that have to agree (or not) with the software's "decisions".

I also see four aircraft shadows, not three - - so I think that the software (or its human operators) did not perform some customary edit(s) on this particular portion of the imagery, leaving these multiple aircraft images visible. I do agree that the higher speed of the airplane (and also accelerating, considerably - - unlike a highway vehicle) probably have to something to do with this "effect" being visible on this image.

For what it's worth, I have looked at DFW, ORD and LHR for similarly aircraft images, and they are conspicuously absent. Makes me think that Google Earth DOES routinely "clean up" such images to remove the distraction of moving objects. The same things is true for certain sections of highway which are clogged almost every single hour that the sun is shining. In general, highways appear very much vacated. They can't be harvesting ALL these images on "Sunday mornings" and other low traffic times. I assume that they have graphic algorithms for making highways look less clogged (and a certain amount of human operator involvement with that as well).

capxxx

(I used to do work in remote sensing so can give some educated guesses ...)

Google buys its satellite images from GeoEye, I believe. GeoEye buys its images from a collection of satellite companies. So its probably not Google doing any software manipulation of the images.

Those satellites have a fairly high return-to-scene rate (between, say, every 5 days to every 100 days), so they probably just pick the best-looking image -- low traffic, daylight, no clouds, no shadows from clouds, etc, -- among a large set of options. All of Google Earth is in bright sunshine, and I think they tend to prefer times when the leaves are off the trees,. too.

The satellite is moving in relation to earth, and they tend to have multiple cameras -- so the duplicate images due to motion and multi-images probably is routinely removed (based on angles and trigonometry and such). But writing software to identify cars on highways (and planes) and remove duplicates, sounds hard. What would be the point of cleaning up a highway image, anyway?

Maybe the plane was traveling in the opposite direction as the satellite and a plane was high in the air (the runway is just coincidence) -- then you'd get that kind of effect when you travel in a car and the nearby picket fence appears to move faster than the tree on the horizon. Or maybe there are two planes (and their shadows) that are many thousand feet apart in vertical distance.

Echnaton

I found the same picture with Google Earth and got a better resolution. It is the same aircraft (you can read "Lufthansa" on the hull) and I found that cars were doubled, too.

So, this are triple pictures. I know a digital camera that does the same in order to remove blurring (the Fuji F70 EXR).

Mystery solved.

rex

>

It remains my (original) contention that there are NOT three aircraft in rapid close-together serial take-off... only one (but it could also be two, I suppose)...

...neverthless, the ability to read the Lufthansa on the hull certainly does not indicate that the thre images are the same aircraft - - given that this is the Frankfurt airport. I can't help but think that quite often, two, or even three Lufthansa aircraft take off from FRA, one right after the other, and from overhead they might easily be indistinguishable, one from another.

...and I also disagree with...

>

Because it appears that we can see shadows which are comparable in size to the overhead-viewed image(s) of the plane(s), I submit that this means they are still quite low in altitude. I don't think that an object the size of a commercial airplane casts a very identifiable shadow on the ground once it gets above a thousand feet or so.