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How Google Earth Images Are Made
An anonymous reader writes "The Google Librarian Central site has up a piece by Mark Aubin, a Software Engineer who works on Google Earth. Aubin explains some of the process behind capturing satellite imagery for use with the product. 'Most people are surprised to learn that we have more than one source for our imagery. We collect it via airplane and satellite, but also just about any way you can imagine getting a camera above the Earth's surface: hot air balloons, model airplanes - even kites. The traditional aerial survey involves mounting a special gyroscopic, stabilized camera in the belly of an airplane and flying it at an elevation of between 15,000 feet and 30,000 feet, depending on the resolution of imagery you're interested in. As the plane takes a predefined route over the desired area, it forms a series of parallel lines with about 40 percent overlap between lines and 60 percent overlap in the direction of flight. This overlap of images is what provides us with enough detail to remove distortions caused by the varying shape of the Earth's surface.'
"Most people are surprised to learn that we have more than one source for our imagery." Must be people who never leave the US border? How can you possibly miss what a hodge-podge of a patchwork Google Earth is? It's especially apparent if you zoom in on a small island.
My bad.
don't confuse google maps with google earth. They have distinct purposes, and excells at them.
insight through the mind
I sure wish Google Earth had a way to adjust the brightness/contrast of individual tiles or maybe the view window. Some areas are very dim and need brightness/contrast adjustments.
Anyone who has thought about this for more than half a second, or has looked at anything more than just their backyard would realise that it is cobbled together from various sources.
Engineering is the art of compromise.
This makes it sound like Google actually did this work themselves with mental images of Googlites flying kites and riding hot air balloons. That is patently untrue. Most of the images in Google earth have come from other sources (government agencies, scanned aerial photos, etc).
Engineering is the art of compromise.
Maybe you should download and try Google Earth which....
requires 3D hardware, can do smooth zooms, tilts, and pans, and showa the world with elevation.
Google Earth IS the evolved version of the Keyhole client you referred to.
Actually according to our most detailed imagery, your ass isn't shiny and contains only about 1% metal, mostly calcium, potassium, sodium and magnesium ions. -Google team
A friend of mine is a local flight instructor and has done a few flights for Google Maps crew. Perhaps they were just doing specialized by-request work, but in this case it was a dude with an SLR and a big lens shooting out the window of a Cessna.
I was skeptical too, but that’s what he tells me.
Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
I was one of the Aerometric-Alaska flight operators that took photography in 2006 while on-board a variety of small planes. The film we used was generally Kodak 2444, with 9' x 9' shots. After development, these prints can then be scanned at a resolution comparable to roughly that of an 11 megapixel camera. As the article states, these photos are usually taken in succession with 60% overlap. This is what has allowed people to generate topographic maps for decades, even before complex computer interpolation and computer graphics capabilities were present. Stereoscopic perspective of the same area of land taken from 2 separate angles allows people to determine differences in height, in case anyone has ever wondered how that worked. Nowdays, surveys and digital radar scanning is where most of the information that modern topography uses tends to come from.
Actually there's no need for a camera's "panoramic" mode any more. Check out Autostitch , a free for personal use program created by researchers at UBC. Essentially you take as many pictures as you want with varying amount of overlap. Each picture can be rotated differently and even vary somewhat in exposure, and this program automatically figures out which ones go where, even throwing out ones that are not part of the scene. It takes a ton of ram and some CPU speed but the result is better than any other method I've seen. Some examples here at the bottom of this page: AZ Snow Pictures.
4275 Athens-Boonesboro Road, Lexington, Kentucky 40509
r ls=en&q=4275-athens-boonesboro&btnG=Search
y j8t&style=o&lvl=2&tilt=-90&dir=0&alt=-1000&scene=2 023607&encType=1
Seems an appropriate opportunity to ask the question: Why the fuck is this residence blurred out? It appears to be someone who is a planholder in Kentucky's state health care plan, so maybe they're a powerful state government official:
http://www.google.com/search?hl=en&client=safari&
BTW, why are the addresses of all Kentucky state planholders publicly available and indexed on Google? That is just pathetic data security...
Anyway, the same address is accessible (and not blurred) via Microsoft Live!:
http://maps.live.com/default.aspx?v=2&cp=q9wwps7y
And appears to show two residences with pools in the back yard. Nothing to hide. Property records indicate that they were formerly owned by a lawyer named William Hurt, who practices in Lexington but now lives at another address. Given the rather inconspicuous pictures of them at the Microsoft Live flyover, the fact that they're blurred out on Google Maps is even more conspicuous than just showing the pictures of the two houses that are blurred.
There may be a high-powered state government official living there, but how did they have enough influence to get the pics blurred out? Were they skinnydipping in the pool? I don't think the map would show enough detail to make that a problem. Any ideas?
Google Earth used to be cool, but it's turning into one massive billboard (perhaps one of the ideas all along). In Sydney for Australia Day, Google (and whatever the Microsoft's copy of it is called) did flyovers with huge pre-publicity. People lay out banners, .com wannabees stuck huge logos on their rooves, people picnicked and love-maked all on the hope of becoming 'famous' (with four million other people). Google put it up and at the end of the day, Sydney wasn't Sydney any more. Instead, Sydney was transformed into one big banner ad:
- day-flyover/
n s_demolished/page2.html
http://googlesightseeing.com/2007/02/27/australia
Then we had the world's biggest photojournalism fakery with Google restoring New Orleans to pre-Katrina. Beyond weird. Did they think the residents wouldn't notice?
http://www.theregister.co.uk/2007/04/02/new_orlea
Google Earth is sponsored infotainment. If you'd like to see Earth without the Ads, there's a little mob called NASA I hear are going places: http://visibleearth.nasa.gov/
The process he described is the same process that imaging companies have used since LONG before Google Earth acquired Keyhole. And many of those companies are still doing it. In fact, many of them are the same companies from which Google is now acquiring the imagery used in Google Earth. Does this guy really believe Google is conducting their own overflights and sending up their own balloons? Does Google now have their own satellites, too?
If you think a regular flight is boring, you have never been the pilot on a picture taking flight:
1. You fly straight (GPS and autopilot) for half an hour, then
2. turn around, and fly back.
3. Repeat this until the fuel is used up.
4. Refuel and repeat.
The only fun thing to do is when you turn: with the google photographer on his stomach with the camera, you do a Chandelle or Wing-over http://en.wikipedia.org/wiki/Aerobatic_maneuver This gives you a few seconds of weightlessness, and with the photographer in the back now floating in the cabin, he smacks on the floor with an "ooommpf" when gravity is reapplied.
The first few times he complains, but you just tell him you have to do this to properly align the aircraft for the reverse leg of the flight pattern.
So the routine for the photographer is something like:
1. click, click, click, click, click, click, click, click, click, click
2. "Whoooooooooo, ooommpf"
(I wonder if he reads this?)
don't cut it off www.mgmbill.org
So Google is basically saying that anyone willing to help them out can go fly a kite?
Hmpf.
Beware: In C++, your friends can see your privates!
Because (AFAIK) digital cameras don't exist in the large format form factor that [film] cameras for aerial photography uses. Even if they did, from typical aerial photography altitudes digital camera are inferior in resolution to existing films.
I thought film was dead too (or rather, I thought it should be), until we recently had to order 40k acres of imagery at six-inch-pixel resolution, and I talked with the folks who own the cameras and fly the planes.
When it comes to airplane-based commercial aerial photography, film remains the most wide-spread capture medium. A decent camera can easily cost more than $1 million -- and you'll probably want two to capture stereo pairs, and don't forget a spare. For now, digital cameras are no less expensive and offer few benefits over their film-based bretheren.
Both require a GPS-controlled platform, capable of shooting several shots a second. After scanning, typical film-based photography is for all intents and delivers a 250+ megapixel result -- the digital alternative to such a beast is not exactly easy to find, and definately not inexpensive. Those are big files tool, and lossy compression is a bad, bad thing. Given the cost of fuel these days, redundancy is essential when it comes to data. That means being able to store four-to-twelve uncompressed (or minimally) 250+ megapixel images on two systems of one type or another, both of which must be rugged enough to withstand their environment.
Last but not least are the lenses. Outside the world of physics research, the highest quality land-camera lenses, even those in the cinematagraphic world, exhibit far more distortion than is acceptable for survey-grade aerial photography.
So, you're right. And yes, it sucks. We're betting environmental regulations will probably be the nail in the coffin over the next decade.