Author Topic: Stereo parallax  (Read 3384 times)

Offline MrSpock

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Stereo parallax
« on: May 04, 2012, 02:40:58 AM »
Hi,

I got this link from a HB claiming that they are proof of the fact that we never went to the moon...

http://www.aulis.com/stereoparallax.htm

Comments? I´m fighting with this guy on a swedish forum regarding the hoax.

Offline ChrLz

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Re: Stereo parallax
« Reply #1 on: May 04, 2012, 07:06:17 AM »
Hmm.  I'm not real happy about giving a long-debunked (and completely-debunked) website any new hits, just to help out on some other forum.

Is this not something covered here:
http://www.clavius.org/jackwhite.html

If it's something genuinely new, and you wish to post the argument here or a link to the forum, then fair enough... maybe?

Otherwise how do we know that you aren't Jack White spamming that ridiculous site?  Seriously, visiting that site will drop your IQ by tens of points within seconds.

Offline JayUtah

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Re: Stereo parallax
« Reply #2 on: May 04, 2012, 10:16:46 AM »
So a researcher goes off to create a new technique for visualizing parallax, applies it to one toy example, and then proceeds to use that method to "invalidate" the Apollo photographs -- and only they.

He skipped the part where he validates that his method works for parallax at all relative scales (including the miles-long scales alleged in lunar photography).  Parallax does not exhibit linear behavior as distance varies.  The ratio of distances from the viewer to two objects, the d1/d2 ratio in the projection math, determines the lateral effect of parallax observed between those objects.  Hence if two distant objects are used as references such that the distance ratio approaches 1, little difference will be observed.

He skipped the part where he validates that his method works for determining via parallax whether subject photographs were taken in the field or in a studio, as he alleges the Apollo photographs were.  Conspicuously missing is any study of the method as applied to known studio photography.

He skipped the part where he studied whether any distortions in the image might be caused by the non-linear effects of the Zeiss Biogon lens, a feature for which it is justly famous.  In the larger sense, the researcher here has failed to perform any sort of error analysis.  He simply attributes all anomalous data to the hypothesis he wants to test:  that Apollo photographs were taken indoors.

He skipped the part where he determined that photographs taken in a domed studio, as he alleges, differ from photographs taken in the field in a way that his method can discern.  This is pure question-begging.  He determines analytically that a certain degree and type of distortion would occur if the backdrop were attached to a concave surface, but fails in any way to validate or confirm that it would produce the effect seen.

In short is a very common story:  snappy visuals that seem to illustrate an important scientific point, with absolutely no scientific rigor placed behind it.  Pseudoscience.  He hopes the viewer will be impressed with his ability to distort photographs seemingly at random and make animated GIFs and assume that he got all the rest of it right.
"Facts are stubborn things." --John Adams

Offline Echnaton

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Re: Stereo parallax
« Reply #3 on: May 04, 2012, 10:17:41 AM »
Welcome to the forum MrSpock.  Now that a link to a article that addresses the issue has been posted, please tell us any question that you have that have not been answered?  Do you think the missions were hoaxed?  Are you uncertain on how to evaluate the information presented? Does the link simply raise doubts that lead to feeling uneasy about what you have previously thought to be true, if so what are your doubts? 

Most hoax proponents practice what can be generally classified as raising fear, unease and doubt.   Shortened as FUD.  It plays into the natural process we all go through of finding out that some things we believe are really not as accurate as we had imagined.   The remedy for FUD is education that results in greater certainty of knowledge.  Something the FUD mongers aren't selling.  So if you have questions, this is the right place. ask away.
The sun shone, having no alternative, on the nothing new. —Samuel Beckett

Offline MrSpock

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Re: Stereo parallax
« Reply #4 on: May 04, 2012, 01:58:46 PM »
First off - I am absolutely not a hoax believer nor Jack White, just an ordinary swedish male who fights the hoax on a swedish message board. I do not doubt the moon landings in any way!

The guy who linked to the web page in my first post is with 99% certainty mcclellan from the old forum and the old thread regarding the Pokrovsky theory: http://apollohoax.proboards.com/index.cgi?board=theories&action=display&thread=2732&page=3
For a few months he fought with the exact same answers and "proofs" as in the thread above (but in swedish).
Then he became quiet and a couple of days ago he came back with the link regarding the stereo parallax.

Since I am not a photography expert or good at discussions I just thought if I throw the question in this forum I might get some answers that I can bounce back at him on the swedish forum.

By the way - thanks for the answer Jay Utah!

Offline JayUtah

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Re: Stereo parallax
« Reply #5 on: May 04, 2012, 03:10:42 PM »
First off - I am absolutely not a hoax believer...
That was apparent in your first post.  I'm sorry that it seems you're being asked to account for another's claims.  Unfortunately many first-time posters arrive here "just asking questions" as a way to put critics off guard.

Quote
Since I am not a photography expert or good at discussions I just thought if I throw the question in this forum I might get some answers that I can bounce back at him on the swedish forum.
Sure, I'm glad my answer helped.  In general it's cumbersome to discuss here something that's happening in other forums, but if you find our answers useful then I'm willing to keep helping.

Referring again to http://www.aulis.com/stereoparallax.htm I find:

Step 3 of the proposed process mentions applying transformations in image space, such as perspective distortions, independent x- and y-axis scaling, and rotations.  First, some of these would not be projection-preserving, and thus are invalid in rectification.  Second, there is no mention made of how the parameters for these transformations are derived.  Hence they amount to manual processing and therefore cannot be scientifically reproducible.

The proposed antiprojection, La = Lb b/a, is linear.  Most lenses do not implement a linear projection model, and the Zeiss Biogon explicitly does not.  Hence the mathematical framework is simplistic and incorrect.

Fig. 7 purports to show a parallax difference between two Apollo photos that include a distant background.  The author believes that because a geometric change is apparent in the blink-comparator, this should be attributed to parallax.  In fact the method fails.
  • No values are given for any rotations, distortions, or other transformations applied to the photograph(s).  The results are therefore irreproducible and scientifically invalid.
  • A simple contrast expansion of the "difference" image shows misalignment in the ridge lines consistent with a rotation between raster images roughly coincident with the original line of sight.  The author has misapplied his broken method and thus interprets the difference in rotation (and possibly subsequent distortive attempts to correct it) as parallax.

Figs. 10 and 11 are similar.  The author applies uncontrolled, arbitrary image-space manipulations that are not projection-preserving, then proceeds to attribute resulting misalignment of the raster to parallax.  And again, no method is shown for deterministically deriving the distortion parameters; it is purely subjective and therefore irreproducible.

The author then imagines that the effects he introduces through non projective-preserving manipulations are explicable in affine space by a sort of concave screen.  This is pure fantasy:  a much simpler explanation exists, that of the ineptitude of the author's image-space manipulation and his fundamental misunderstanding of the actual projective geometry at work here.  He has proven absolutely nothing other than his ability to produce in one instance a distortion map that corrects for the distortion he previously applied in another instance.  There is absolutely nothing here that is valid or proven to be a method for determining the authenticity of photographs.
"Facts are stubborn things." --John Adams

Offline Echnaton

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Re: Stereo parallax
« Reply #6 on: May 04, 2012, 03:19:32 PM »
First off - I am absolutely not a hoax believer

I see that now.    People here sometimes get a bit knee jerk to a short initial post,  and that is reflected in my previous post.    Sorry to have just skimmed and replied.
The sun shone, having no alternative, on the nothing new. —Samuel Beckett

Offline ka9q

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Re: Stereo parallax
« Reply #7 on: May 04, 2012, 10:31:51 PM »
He skipped the part where he studied whether any distortions in the image might be caused by the non-linear effects of the Zeiss Biogon lens, a feature for which it is justly famous.
This was my first thought when looking at the pictures. I immediately noticed that the reseau marks had shifted quite a bit between each pair of pictures, meaning that the camera was pointed in different directions and that any geometric distortion in the lens would change the shape of even the distant scenery. That's one of the reasons the reseau marks are there. They're usually cited as accounting for any stretching of the film, but they would also help locate each feature within the lens geometry. You'd have to know what that geometry is to correct those distortions, but I presume that's known, and the marks are a lot more precise than the edges of the frame.

I didn't know until you just said so that the Biogon was "justly famous" for its non-linear effects.

Offline ka9q

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Re: Stereo parallax
« Reply #8 on: May 04, 2012, 10:39:28 PM »
Pseudoscience. 
It certainly is pseudoscience, but I have to say that it was much better-looking pseudoscience than what usually passes for "evidence" that Apollo was hoaxed.

I didn't fully understand each of his steps as I didn't think he was worth that much effort. But I got the impression that, at one point, he distorts the image in a totally arbitrary fashion with many degrees of freedom and then complains that the background "parallax" disappears, thus "proving" that the background was projected on a screen. Wait -- wasn't it his original complaint that there shouldn't be any parallax on the distant scenery? Or we we supposed to forget that?


Offline AstroBrant

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Re: Stereo parallax
« Reply #9 on: September 20, 2014, 01:13:18 PM »
First off - I am absolutely not a hoax believer...
That was apparent in your first post.  I'm sorry that it seems you're being asked to account for another's claims.  Unfortunately many first-time posters arrive here "just asking questions" as a way to put critics off guard.

Quote
Since I am not a photography expert or good at discussions I just thought if I throw the question in this forum I might get some answers that I can bounce back at him on the swedish forum.
Sure, I'm glad my answer helped.  In general it's cumbersome to discuss here something that's happening in other forums, but if you find our answers useful then I'm willing to keep helping.

Referring again to http://www.aulis.com/stereoparallax.htm I find:

Step 3 of the proposed process mentions applying transformations in image space, such as perspective distortions, independent x- and y-axis scaling, and rotations.  First, some of these would not be projection-preserving, and thus are invalid in rectification.  Second, there is no mention made of how the parameters for these transformations are derived.  Hence they amount to manual processing and therefore cannot be scientifically reproducible.

The proposed antiprojection, La = Lb b/a, is linear.  Most lenses do not implement a linear projection model, and the Zeiss Biogon explicitly does not.  Hence the mathematical framework is simplistic and incorrect.

Fig. 7 purports to show a parallax difference between two Apollo photos that include a distant background.  The author believes that because a geometric change is apparent in the blink-comparator, this should be attributed to parallax.  In fact the method fails.
  • No values are given for any rotations, distortions, or other transformations applied to the photograph(s).  The results are therefore irreproducible and scientifically invalid.
  • A simple contrast expansion of the "difference" image shows misalignment in the ridge lines consistent with a rotation between raster images roughly coincident with the original line of sight.  The author has misapplied his broken method and thus interprets the difference in rotation (and possibly subsequent distortive attempts to correct it) as parallax.

Figs. 10 and 11 are similar.  The author applies uncontrolled, arbitrary image-space manipulations that are not projection-preserving, then proceeds to attribute resulting misalignment of the raster to parallax.  And again, no method is shown for deterministically deriving the distortion parameters; it is purely subjective and therefore irreproducible.

The author then imagines that the effects he introduces through non projective-preserving manipulations are explicable in affine space by a sort of concave screen.  This is pure fantasy:  a much simpler explanation exists, that of the ineptitude of the author's image-space manipulation and his fundamental misunderstanding of the actual projective geometry at work here.  He has proven absolutely nothing other than his ability to produce in one instance a distortion map that corrects for the distortion he previously applied in another instance.  There is absolutely nothing here that is valid or proven to be a method for determining the authenticity of photographs.

I was going to start a thread on this, but i saw that there was already a thread on it.

If and when I get off my butt and start making videos again, I would like to do one on Oleynik's analysis. Some of my critics and friends have suggested that I pay too much attention to relatively weak and insignificant hoax believers. So I decided to take on Oleynik. (Colin Rourke, too.)

I've read your comments and have already made some of the observations you have made here. The real challenge is that on YouTube I have to keep my video at a level which at least some hoax believers, (and Apollo defenders), can understand. Indeed, I have to be able to understand it myself.

Before getting into details and soliciting all sorts of advice from you, let me at least ask if you would be willing to do that. Of course, your help will be duly noted in my video. I'd like to get other people's ideas as well, so do you think I should post a new thread on this?
May your skies be clear and your thinking even clearer.
(Youtube: astrobrant2)

Offline JayUtah

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Re: Stereo parallax
« Reply #10 on: September 20, 2014, 01:16:15 PM »
Sure, I can help, time permitting.  I really prefer to avoid the YouTube ecosystem for debate on these matters, but that seems to be your forte.
"Facts are stubborn things." --John Adams

Offline AstroBrant

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Re: Stereo parallax
« Reply #11 on: September 21, 2014, 12:47:11 AM »
Sure, I can help, time permitting.  I really prefer to avoid the YouTube ecosystem for debate on these matters, but that seems to be your forte.

No, no, I don't want you to have to go to YouTube. I'd like to have the discussion here. I want to get what information I can from you since I find my video idea to be quite challenging, especially when trying to keep it at a level that most YouTubers could follow.

I can see that the lens distorts the field. In fact, when Oleynik shows the contour grids of how he thinks the projection screen is shaped, he is probably making a pretty good distortion grid for the lenses, or at least the portions of the lenses that were involved in a particular photo. One criticism I plan to make involves why in the world anyone would think that NASA made these warped projection screens when they would only cause distortion. And gee, how many did they have to make? And HOW do you make a large projection screen which is contoured in all three dimensions?? That would seem awfully unnecessary and costly.

I was also already planning to criticize him for this "algorithm" he used but gave no details on.

One thing that concerned me was when I looked at an article on the Biogon lenses and how it claimed that they were among the least distorting lenses in the market. I see that you didn't describe them that way. Were they pretty bad? BTW, I don't understand their distortion charts and probably shouldn't use them in my video.

Don't worry about time. I've got plenty. (I hope). When I finally get to making my video, I will upload it unlisted and ask you to give me feedback on it. I've done this kind of peer review with people before. This time I'm very interested in your ideas before making it. Give it some thought and tell me what you think should be included in a ten minute video.
May your skies be clear and your thinking even clearer.
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Offline nomuse

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Re: Stereo parallax
« Reply #12 on: September 21, 2014, 03:26:03 AM »
What amuses me is the thought that a studio shot made in the early 1970's would have not just a curved cylorama over 80' in width, but one with a compound curve. If there was ever a film that painted a large backdrop on a spherical surface, I haven't heard of it.

Pretty ambitious for an outfit with cardboard and tinfoil set pieces, and only a half-dozen styrofoam rocks they re-used over and over, eh?

(Once again, the hoaxies have come up with a scenario that would only work if there were a half-dozen pictures. Not hundreds of them. Not panoramas shot at multiple stations. Not freaking full-motion video from a rover as it rides for twenty minutes at a time across the landscape!)

Offline ChrLz

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Re: Stereo parallax
« Reply #13 on: September 21, 2014, 05:15:51 AM »
...One thing that concerned me was when I looked at an article on the Biogon lenses and how it claimed that they were among the least distorting lenses in the market. I see that you didn't describe them that way. Were they pretty bad? BTW, I don't understand their distortion charts and probably shouldn't use them in my video.
Note that this is an amateur enthusiast talking - happy to be corrected...
Is that the distortion info in this document?:
https://www.hq.nasa.gov/alsj/Biogon5.6_60mm_ZEISS.pdf

If so, then that info (which looks theoretical rather than measured..) tells you that the lens tends (as you move outwards from the image centre) towards very slight barrel distortion (V in the graph) up to a maximum at about 26mm radius (u in the graph), then comes back to zero at about 35mm radius, then heads towards pincushion distortion after that (which is outside the film size..).  They claim the maximum amount of distortion is only 0.002% (in fact a bit less) in either direction.

I'll defer to Jay about the film gate size (69mm (=2u so u=34.5mm) I think), but that graph suggests that at the edges of the image frame (radius ~ 35mm) there is almost zero distortion, and that the slight 'barreling' that occurs as you head outwards is pretty much negligible even at its peak at 26mm out.  Did they really mean 0.002% and not a *ratio* of 0.002, ie 0.2%..?

I have my doubts about such stellar performance.  The best way to measure curvilinear distortion is to .. well, duh .. measure it - ie take a picture of a test grid (at several focal distances to be sure to be sure..) and then check what was recorded on the film.  I've not seen any distortion charts for the f5.6 60mm, but they may be out there.. or perhaps we just need to find one (ie the lens) with a helpful owner..?  :)

Offline darren r

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Re: Stereo parallax
« Reply #14 on: September 21, 2014, 06:20:55 AM »
What amuses me is the thought that a studio shot made in the early 1970's would have not just a curved cylorama over 80' in width, but one with a compound curve. If there was ever a film that painted a large backdrop on a spherical surface, I haven't heard of it.

Pretty ambitious for an outfit with cardboard and tinfoil set pieces, and only a half-dozen styrofoam rocks they re-used over and over, eh?

(Once again, the hoaxies have come up with a scenario that would only work if there were a half-dozen pictures. Not hundreds of them. Not panoramas shot at multiple stations. Not freaking full-motion video from a rover as it rides for twenty minutes at a time across the landscape!)

Absolutely! What makes me laugh is when they try to use Capricorn One as an example of how the pictures could have been faked, when the Mars shots in that film consist of one tiny, tightly-framed set, around which the camera doesn't move!
" I went to the God D**n Moon!" Byng Gordon, 8th man on the Moon.