April 30, 2007

They use film?

Filed under: Google, map — ubikcan @ 8:11 am

While I thought I knew roughly how aerial photography is carried out for things like Google Earth, I had no idea that film, not digital, imagery is collected.

Apparently the people who do all this imagery collection in planes are also very worried about “environmental regulations” putting a stop to it. I must say they might be right, then we’d only have satellites.

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.

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