There Are Giant Camera Resolution Test Charts Scattered Across the US | Hacker News Reader

There Are Giant Camera Resolution Test Charts Scattered Across the US

petapixel.com

166 pointsrpledge46 comments

"Even satellites can utilize the charts. Here’s a chart as seen by the satellite used for Google Maps"

It's not clear that that is a satellite photograph. Just because it was taken from above it doesn't mean a satellite did it. Mapping services (such as a Google's) do a disservice to call all this overhead photography 'satellite'. It's the sort of looseness that causes people to think cellular telephones also talk to satellites.

I just spoke to someone who thought that internet connections from the US to Europe go via satellite because there is so much water in between and you cannot just put a cable there. The cables are amazing (baffling even) but come on, they've been there for 150 years!

> Two American commercial satellite imagery firms — DigitalGlobe and GeoEye — have joined forces with the U.S. Geological Survey (USGS) in support of the global team of space and satellite agencies that constitute the International Charter "Space and Major Disasters".

-- http://www.usgs.gov/newsroom/article.asp?ID=1647

> GeoEye satellite imaging technology is state-of-the-art. The geospatial data we capture provides clients with the highest resolution, most accurate satellite imagery in the world. ... We own and operate a constellation of Earth-imaging satellites and an international network of ground stations.

-- http://www.geoeye.com/CorpSite/products/earth-imagery/geoeye...

^ They even have pictures of the satellites (in case there is still any question that GeoEye is being misleading when they use the word "satellite" ;P).

What do you think the odds are that San Bernadino paid for aerial photos that provide the highest resolution coverage?

Can you say more? I am more than happy to believe I'm analyzing the copyright wrong. Is the idea that that location is covered by a few different things, and the copyright is based on the location, not the data actually being shown? I had assumed that there was some complex relationship between the USGS and the localities involved in the photography.

Not really, I don't know a lot about it. My assumption is that Google shows attributions by lat/long and not zoom. I found one page about it, it doesn't say much:

http://www.google.com/permissions/geoguidelines/attr-guide.h...

I also assume that the USGS collects imagery from localities, but I think they are simply aggregating anything of sufficient quality that would be available under a FOIA request (or so, basically, cooperating with anyone that cooperates).

edit: USGS would be pulling in local data because it was more recent.

It's not that far off, there is a ton of satellite photography in Google Maps. It's the other way around, but satellites talk to cell phones and I don't fault people for not knowing it's one-way.

but satellites talk to cell phones

Wait wat? I honestly didn't know this (aside from a cell phone with extra capabilities, like gps).

I thought all phone communications took place with cell towers (except, of course, for satellite phones).

GPS is what I was referring to.

I hope you are joking.

Cellular telephones do _not_ transmit or receive phone calls from satellites.

http://en.wikipedia.org/wiki/Cellular_network

No shit, I was referring to GPS (one of the more used features of a phone and it's commonly known as being satellite based).

> It's the sort of looseness that causes people to think cellular telephones also talk to satellites.

Anyone who hasn't heard of a "cell tower" in 2013 just doesn't care about what makes the phone go. Cell phones have been around, talking to towers and not satellites, for decades. You can't help everyone.

The source for this PetaPixel article is the Center for Land Use Interpretation, a really neat organization. http://www.clui.org/newsletter/winter-2013/photo-calibration...

Here's a google maps link to one of the charts mentioned, on Edwards Airforce Base:

https://maps.google.com/maps?q=Edwards+AFB,+East+Kern,+Kern,...

Fascinating that there are air craft relics near the charts. I can only imagine that is part of the calibrating: so they can tell how large an aircraft is and what resolution they get for the size.

Indeed, plus one of the aircraft is one of only two remaining examples of the X-21 [0]. I suspect the other is also derelict on the range somewhere.

http://en.wikipedia.org/wiki/Northrop_X-21

Can we derive the implied resolution of government satellites by the test charts?

Is this test pattern in use in other known research?

Most of the test patterns I've encountered in using 'OpenCV' [1], 'laser scanning'[2], and 'structured light scanning' [3] have used equal sized geometric shapes. Not increasing in scale, so maybe that's useful.

[1] http://graphics.stanford.edu/~vaibhav/projects/calib-cs205/c...

[2] http://www.david-laserscanner.com/wiki/_media/user_manual/sc...

http://www.sciencedirect.com/science/article/pii/S0143816607...

[3] http://opticalengineering.spiedigitallibrary.org/data/Journa...

It is known as the 1951 USAF Test Chart, and it is and was a standard:

http://en.wikipedia.org/wiki/1951_USAF_resolution_test_chart

Exactly what I was looking for, thanks.

It seems the 'Milspec' status is:

  MIL-STD-150A, dated 06 January 1998, is hereby cancelled without replacement.

With as many multi-spectral instruments we have floating about, I wonder what other shapes, compositions, or controlled temperature gradients might be in use under our noses.

Don't think spatial calibration, think eye chart: https://www.google.com/search?q=eye+chart

It's very common in microscopy, to check your resolution.

Throw away business idea: QR codes for large tract real estate listings.

The prerequisite being a 'Maps' site with <weekly aerial updates. While relatively plausible today (a few styrofoam drones, camera arrays, pay fer acre for 'crowdsourcing', ...)[1], the legal woes are frightening.

[1] 'relatively plausible' in relation to 'cubesats' and other aerospace driven monitoring.

A lot of real-estate sits for years. Weekly photos aren't really necessary.

How about just a large For Sale with an 800 number? If the property is under an approach to a busy airport. The audience being, of course, all those bored folks in window seats with electronics turned off below 10,000 feet.

Design your sign. Slice your image into two or three horizontal stripes. Then email your slices to one of those vinyl banner sign companies, to be printed on 8' x 50' strips.

One of the features of real-estate development is that a lot of research tends to be done anonymously to avoid tipping one's hand. In addition, many tracts of interest are not near airports, etc.

Also, large compasses about 1km in diameter: http://goo.gl/maps/6wTtb

Those aren't for the same purpose, they're for test pilots to use when landing on the lakebed runways that you can see next to the compass.

Both the X-1 and X-15, amongst many other experimental planes, landed on the lakebed rather than on conventional runways at Edwards AFB.

Why did they land on the lake bed as opposed to runways?

Because in experimental craft, one doesn't want to have to line up with a runway when the controls have stopped functioning or a wing has partly fallen off.

Once, when a test pilot landed the X-15 on a lakebed, the fuselage broke in two:

http://www.air-and-space.com/x-15%20forty%20years%20later%20...

Quote: "The X-15-2 on Rosamond Dry Lake following mission 2-3-9*. The fuselage failed when the nose gear impacted the ground. The shock absorbing ability of the front landing gear strut was impaired by foaming of the oil in the strut when it was extended. The back of the X-15 broke at a structural join behind the cockpit."

What lutusp said plus the fact that the lakebed runways are much, much longer than the tarred runways. So the combination of much more width and much more length means its far safer to get an aircraft like the X-15 on the ground.

If it's a compass, then why is it 20 degrees off?

The magnetic north pole isn't in the same spot as the geographic north pole -- see http://en.wikipedia.org/wiki/Magnetic_declination.

Does ATC use magnetic bearings?

Yes. This is why runway numbers (which are the heading with the last digit removed) are known to change from time to time. Aviation charts also display the variation between magnetic and true north. (See the purple dashed lines with 14/15° W http://skyvector.com/?ll=40.55464932694554,-70.9421666906757... )

Idea: remember the EURion constellation? http://en.wikipedia.org/wiki/EURion_constellation

It's a pattern of circles that's printed on money, and when printers detect it in a file they will refuse to print that file. I wonder what would happen if we similarly embedded this pattern in landscapes. Would it prevent printing aereal photo's?

fiducials, not so much for a 2-D 'where', but to help deal with the blurring (http://what-if.xkcd.com/32/)

Any idea why some of them, especially the images from EAB, appear to cast shadows? That is, the white blocks appear to be bordered by black.

Sometimes these pictures are taken with 3 separate lenses and filters -- one for each color. Then they are merged. Sometimes that could get out of alignment.

Maybe bad sharpening artifacts.

Does anyone know of any of these charts at locations accessible to the public? They appear interesting to look at.

They could have made it a bit more interesting, by coding a secret short message into them (yawn).

But nonetheless, a interesting article.

> by coding a secret short message into them

Maybe there is a secret message in them...

DUN-DUN-DUUUUN!!!

"Be sure to drink your Ovaltine."

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