Author Topic: "Ground truth" - Corona landmarks  (Read 6078 times)

Offline Oersted

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Offline Archibald

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Re: "Ground truth" - Corona landmarks
« Reply #1 on: 04/11/2017 06:25 pm »
That's... amazing. Then it make sense. How do you calibrate a spy satellite, and test its resolution ? I wonder which engineer came with that solution. His coleagues must have thought "he is crazy".
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Online Blackstar

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Re: "Ground truth" - Corona landmarks
« Reply #2 on: 04/11/2017 06:47 pm »
That's... amazing. Then it make sense. How do you calibrate a spy satellite, and test its resolution ? I wonder which engineer came with that solution. His coleagues must have thought "he is crazy".

Resolution test targets existed before CORONA. They were often put on airfields, because that's where the recon planes launched from. There were many complex variations on them. The Soviets had them as well.

Online Blackstar

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Re: "Ground truth" - Corona landmarks
« Reply #3 on: 04/11/2017 07:04 pm »
I'd have to go dig through my materials, but I think that there are two different relevant ground markings:

-calibration markers
-resolution test targets

The resolution test targets had a bunch of white bars of different sizes and distances from each other. These were often located at airfields. There were even portable version (which I think were primarily just pieces of white painted plywood that could be picked up and loaded into a truck).

I think that these calibration markers mentioned in the article were not for determining resolution, but for calibrating the cameras, possibly the mapping cameras (as opposed to the main reconnaissance camera). What the users, and the camera developers, needed to know was what the distance between two points on the film was compared to the ground distance. If you have a square piece of film, and you cover it with equally-spaced dots, are all the dots on that film the same ground distance from each other? Or are the dots near the edges farther apart than the dots near the center? I think that these ground targets were used for that purpose.


UPDATE: The things in the article were known as Controlled Range Network (CORN) targets.
« Last Edit: 04/11/2017 07:43 pm by Blackstar »

Offline whitelancer64

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Online Blackstar

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Re: "Ground truth" - Corona landmarks
« Reply #5 on: 04/11/2017 07:46 pm »
Another article with some better pictures:

http://99percentinvisible.org/article/solve-x-deciphering-calibration-marks-made-classified-spy-missions/

That article also includes the resolution test targets I mentioned.

This story reemerges every few years as a reporter suddenly re-discovers these things.

You can find more info here:

http://journals.sagepub.com/doi/abs/10.1177/107118137702100205


Offline Star One

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Re: "Ground truth" - Corona landmarks
« Reply #6 on: 04/11/2017 08:26 pm »
I wonder if the the KH-11 fleet still need to use things like this?

Online FutureSpaceTourist

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Re: "Ground truth" - Corona landmarks
« Reply #7 on: 04/06/2021 06:43 am »
twitter.com/thejackbeyer/status/1379295907586269189

Quote
This is Corona Satellite calibration target AJ46. In the 1960s 272 of these concrete markers were laid out in a 16 x 16 mile grid in and around Casa Grande, Arizona to aid in calibrating the optics of our first spy satellites.

Instagram.com/p/CNT8Q2GhEjP/

https://twitter.com/thejackbeyer/status/1379297765990129666

Quote
It's fascinating to me that these vestiges of the Cold War still exist, often right alongside modern civilization, if one only knows where to look. I can't imagine living a life in constant fear of total nuclear annihilation, and yet - the threat has never really gone away.

Offline Yiosie

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Re: "Ground truth" - Corona landmarks
« Reply #8 on: 06/24/2022 01:04 am »
Turns out the "Corona" calibration targets were for aerial photogrammetry purposes, and may not be related to the Corona satellites at all.

Candy CORN: analyzing the CORONA concrete crosses myth [dated Dec. 21, 2020]

Quote from: The Space Review
I could not come up with a satisfactory answer why the government would build a fixed optical range with such large targets specifically for CORONA in a post-1966 timeframe and not mention it in documentation anywhere. One website states the targets were calibration targets for CORONA from 1966 until 1972. The targets were supposedly abandoned due to shifting caused by subsidence from nearby ground water pumping. [6] Even Wikipedia has a page about these “Corona Satellite Calibration Targets.” Keen observers will note that while NRO references are listed at the bottom, no specific document is identified with information on either Casa Grande or the concrete cross dimensions. [7]

<snip>

I found what I believe to be the answer on the front page of the Casa Grande Dispatch (Pinal County Edition), dated May 31, 1967: “CG [Casa Grande] Area to be Subject of Precise Photography.” [12]

Walt Wiley’s front-page story tells of a US Army Corps of Engineers effort to create “…an extremely accurate yardstick for dynamic testing of aerial cameras at low and high altitudes.” A follow-up article on October 8, 1968, provides estimated costs and timelines, and a curious statement by Roger Lewis, an aide to Arizona Representative Morris Udall: “I was told the markers would be used for photography testing for aircraft at low or extremely high altitude.” The next sentence is conjecture on the part of Lewis: “[Lewis] added that it was his impression that ‘high altitude’ aircraft would also include satellites.” Lewis’ reason or agenda behind this statement of conjecture is unknown. [13]

And to hammer home the linkage to aerial photogrammetry, I found this description from John O. Phillips the Chief of the Geodesy Division, Coast and Geodetic Survey, circa 1966:

“The resurvey on the original Phoenix, Arizona, test area was completed early in 1963 with modern electronic distance measuring equipment and triangulation methods, and the results were rigidly adjusted during the reporting period. The resurvey and the adjustment were performed to provide accuracy commensurate with currently used aerial photogrammetric equipment…[C]onsiderable progress has been made on surveys to establish another test range (Casa Grande Test Range) just south of the original Phoenix test area. The Casa Grande was designed to be a superaccurate range for use in dynamic calibration of aerial cameras. When completed, the Casa Grande test range will consist of 273 points positioned horizontally and vertically by precision survey methods. Each point will be elaborately paneled, and all points will be located according to an orderly arrangement within a 16-mile square area.” [19]

Online edzieba

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Re: "Ground truth" - Corona landmarks
« Reply #9 on: 06/24/2022 01:45 pm »
I guess a good way to hide your giant geodetic calibration array for satellite imagery is to tell everyone very publicly that it's a giant geodetic calibration array for reconnaissance aircraft imagery, get whoever is doing reconnaissance aircraft imagery to pay for it, and let them use it. As long as you can get your design requirements in place before it's constructed (and make sure they don't get removed by someone asking too many questions about odd requirements) then that's as much involvement in the project as you need. Involvement could even date back to WS-117L given how long the lead time on some of these projects can be (and how long WS-117L's child projects hung around) meaning the only mention of the calibration targets in CORONA documentation would be in a handbook for image analysts detailing target directions - or just advising reference to whatever documentation existed for use of those targets for calibration of aerial imagery.

A more interesting mystery would be if the USSR had constructed similar calibration targets, and if these were known to and used by the US to calibrate imagery during overflights. Or even less likely to have any information available: if the USSR were aware the CORONA/aircraft/etc targets within CONUS and used them to calibrate their overflight imagery.

Offline hoku

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Re: "Ground truth" - Corona landmarks
« Reply #10 on: 06/24/2022 02:26 pm »
<snip>
A more interesting mystery would be if the USSR had constructed similar calibration targets, and if these were known to and used by the US to calibrate imagery during overflights. Or even less likely to have any information available: if the USSR were aware the CORONA/aircraft/etc targets within CONUS and used them to calibrate their overflight imagery.
Gobi desert also features some interesting artificial "artsy" ground patterns near "40.457751,93.378481". Any guess what purpose they might have served? Image distortion calibration at Landsat-type ground resolution distance? Test of automatic pattern recognition to create maps, and identify airport runways, etc? Some pre-/post-strike damage assessment simulation?  Art installation?

edit: USGS maintains a "Test Sites Catalog" of radiometric, geometric, and spatial sites - see https://www.usgs.gov/tools/test-sites-catalog, https://calval.cr.usgs.gov/apps/spatialsites_catalog
« Last Edit: 06/24/2022 03:02 pm by hoku »

Offline libra

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Re: "Ground truth" - Corona landmarks
« Reply #11 on: 06/24/2022 03:35 pm »
And of course aliens pioneered the idea at Nazca...  ;D ;D

https://en.wikipedia.org/wiki/Nazca_Lines


Offline kevin-rf

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Re: "Ground truth" - Corona landmarks
« Reply #12 on: 06/24/2022 08:09 pm »
Nice to see things on the larger scale  :)

I spent my day looking at an US Air Force 1951 test target at the micro scale today. The calibration plate target had some errors that led me to finding out that the MIL-STD-150A target has been deprecated. Sounds like it is better suited for film than digital sensors hence it's retirement.

MIL-STD-150A (NOTICE 5), MILITARY STANDARD: PHOTOGRAPHIC LENSES (16 OCT 2006) [NO S/S DOCUMENT]., MIL-STD-150A, dated 06 January 1998, is hereby cancelled without replacement.

Since someone will ask, Image of defective calibration plate (those circles are 20 um across)


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Offline limen4

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Re: "Ground truth" - Corona landmarks
« Reply #13 on: 06/25/2022 05:54 pm »
Quote

Gobi desert also features some interesting artificial "artsy" ground patterns near "40.457751,93.378481". Any guess what purpose they might have served? Image distortion calibration at Landsat-type ground resolution distance? Test of automatic pattern recognition to create maps, and identify airport runways, etc? Some pre-/post-strike damage assessment simulation?  Art installation?

edit: USGS maintains a "Test Sites Catalog" of radiometric, geometric, and spatial sites - see

It is part of a huge missile target area. A good overview is here https://warontherocks.com/2017/02/has-china-been-practicing-preemptive-missile-strikes-against-u-s-bases/. I remember that one target represents the ground plan of a real city.

Offline hoku

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Re: "Ground truth" - Corona landmarks
« Reply #14 on: 08/22/2022 04:49 pm »
<snip>
A more interesting mystery would be if the USSR had constructed similar calibration targets, and if these were known to and used by the US to calibrate imagery during overflights. Or even less likely to have any information available: if the USSR were aware the CORONA/aircraft/etc targets within CONUS and used them to calibrate their overflight imagery.
Answer to your first question: yes, at least by 1974 the USSR had their own set(s) of calibration targets, and they were apparently repeatedly observed by the US - see "The HEXAGON Story, page 205 (page 191 in the PDF of the 2011 release) 
https://permanent.fdlp.gov/gpo26371/7.pdf

If someone could figure out the exact coordinates of the Tyuratam/Baikonur calibration targets, we could check via USGS EarthExplorer, how frequently these targets were visited.

edit: found the target area at about 45 48 58 N  63 17 45 E
edit 2: calibration targets are not (yet?) marked on the attached map from 1964
edit 3: map from 1980 added, which marks the "RECON TARGET AREA"
https://www.cia.gov/readingroom/document/cia-rdp80t01782r000100800001-8
« Last Edit: 08/22/2022 08:13 pm by hoku »

Online Blackstar

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Re: "Ground truth" - Corona landmarks
« Reply #15 on: 08/22/2022 06:10 pm »
Answer to your first question: yes, at least by 1974 the USSR had their own set(s) of calibration targets, and they were apparently repeatedly observed by the US - see "The HEXAGON Story, page 205 (page 191 in the PDF of the 2011 release) 


Thanks for the reminder on that.

Back in the 2000s, a writer for Novosti Kosmonavtiki magazine did an article about Soviet-era calibration targets, and they had some photos of them. Somebody once sent me the issue, but I have no idea how to search for it on my computers.

Offline JetProp

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Re: "Ground truth" - Corona landmarks
« Reply #16 on: 08/24/2022 11:10 pm »
Quote
I have no idea how to search for it on my computers.
Hello! This is the NK №7, 2001 year, pages 66 - 68. If you write e-mail, i can send to you this number of magazine.
« Last Edit: 08/24/2022 11:12 pm by JetProp »

Online Blackstar

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Re: "Ground truth" - Corona landmarks
« Reply #17 on: 08/25/2022 12:23 am »
Quote
I have no idea how to search for it on my computers.
Hello! This is the NK №7, 2001 year, pages 66 - 68. If you write e-mail, i can send to you this number of magazine.

Thank you. Here you go:


Offline JetProp

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Re: "Ground truth" - Corona landmarks
« Reply #18 on: 08/25/2022 02:17 pm »
Thank you. Here you go:
Very well! Sorry for off-top, you can download all numbers of NK here: https://www.roscosmos.ru/33921/

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