ApolloHoax.net

Apollo Discussions => The Hoax Theory => Topic started by: MrSpock on May 04, 2012, 02:40:58 AM

Title: Stereo parallax
Post by: MrSpock 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.
Title: Re: Stereo parallax
Post by: ChrLz 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 (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.
Title: Re: Stereo parallax
Post by: JayUtah 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.
Title: Re: Stereo parallax
Post by: Echnaton 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.
Title: Re: Stereo parallax
Post by: MrSpock 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!
Title: Re: Stereo parallax
Post by: JayUtah 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.

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.
Title: Re: Stereo parallax
Post by: Echnaton 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.
Title: Re: Stereo parallax
Post by: ka9q 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.
Title: Re: Stereo parallax
Post by: ka9q 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?

Title: Re: Stereo parallax
Post by: AstroBrant 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?
Title: Re: Stereo parallax
Post by: JayUtah 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.
Title: Re: Stereo parallax
Post by: AstroBrant 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.
Title: Re: Stereo parallax
Post by: nomuse 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!)
Title: Re: Stereo parallax
Post by: ChrLz 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..?  :)
Title: Re: Stereo parallax
Post by: darren r 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!
Title: Re: Stereo parallax
Post by: Kiwi on September 21, 2014, 10:31:36 AM
...Not freaking full-motion video from a rover as it rides for twenty minutes at a time across the landscape!)

Small correction -- that's colour movie film that we see taken from the rover when it's in motion, and it often shows the video camera which was always stowed for trips between stations, mainly because the antenna had to be accurately aimed at earth for the video to be transmitted successfully.

One thing you've not mentioned is the multitude of photos taken by the LMP when travelling between stations. In many cases distant rocks can be seen, along with more photos as the rover approaches them. Apollo 17's Turning Point Rock and Tracy's Rock are just two of many examples, and sometimes video or stills can be seen looking back at the route taken and showing the rover's tracks.

There are three types of things that I think have been underused in debunkings of the "filmed in a studio" claims:--

1. The long video clips taken on the EVAs from the Apollo 16 and 17 rovers.  They don't always concentrate on the astronauts and include pans and tilts up, down and around, and they never show any sort of studio environment. No furniture, reflectors, artificial lights, power cords, stands, gantries, or cranes. And most vehicle tracks and footprints can be attributed to either the activities we see or to activities that were otherwise documented.

2.  Long-distance photos or video of the lunar module, which included telephoto shots of the LM from a distance, or wide-angle shots that accidentally included it, such as the panoramas at Tracy's Rock (or Split Rock) at Apollo 17's Station 6, which include a tiny LM in the distance to the right of the top of the rock -- see AS17-140-21493 to 21496.
http://www.hq.nasa.gov/alsj/a17/AS17-140-21493HR.jpg
http://www.hq.nasa.gov/alsj/a17/AS17-140-21494HR.jpg
http://www.hq.nasa.gov/alsj/a17/AS17-140-21495HR.jpg
http://www.hq.nasa.gov/alsj/a17/AS17-140-21496HR.jpg

On the other hand, there are photos that include Tracy's Rock or Turning Point Rock from the vicinity of the LM or the ALSEP site, and there's the upsun video of Jack Schmitt skipping back to the LM when he sings "I was strolling on the moon one day..."

HBs would have trouble describing a realistic studio and setup for the Apollo 16 Grand Prix.

3. Video of astronauts taking panoramas and telephoto shots. For instance, Gene Cernan is on video taking a series of telephotos shots of one of the massifs from close to the rover, and we can see a slight motion of the lens as he presses the shutter. We can also examine the photos he took, and some of them show camera shake because of that lens motion.
Title: Re: Stereo parallax
Post by: gillianren on September 21, 2014, 11:10:24 AM
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!

When I saw the movie, my opinion was that the set was even too small for a TV show.  You'd have to have been extremely careful in every shot not to get the edges of the backdrop.  It was one of the (many) problems I had with that movie.
Title: Re: Stereo parallax
Post by: AstroBrant on September 21, 2014, 09:56:01 PM
(snip...)
Is that the distortion info in this document?:
https://www.hq.nasa.gov/alsj/Biogon5.6_60mm_ZEISS.pdf

Yes, that's it. I could get the general idea but not enough to tackle Oleynik's analysis. thank you for the rest of the information. I may be able to figure it out now, but it seems that the distortions I am seeing are way outside of those specs. maybe there's another reason for it.

One thing I have found for my critique is a stereo pair of pictures taken from the same place, showing significant distortion. The background stretches considerably from one picture to the next, both vertically and horizontally. This would be good for making the point that it must be something other than true parallax that we are seeing since the baseline is of negligible length.
Title: Re: Stereo parallax
Post by: AstroBrant on September 21, 2014, 10:05:38 PM


One thing you've not mentioned is the multitude of photos taken by the LMP when travelling between stations.

Yes, especially in Apollo17. I used about 20 or 30 in sequence in one of my videos, all centered on the western peak of South Massif. IIRC there were over a hundred pics from one traverse.

Re. Grand Prix. Another tough one to pass off as a studio shot is Jack carrying the ALSEP equipment out. He disappears completely from sight over one ridge.
Title: Re: Stereo parallax
Post by: nomuse on September 21, 2014, 10:31:41 PM
The clip I remember is...I think it was "House Rock," but I can't remember the flight. Shot from the parked rover, the astronauts go walking down a gentle slope towards a boulder. And keep walking. And keep walking. Because the boulder is the size of a small house. And if you are imagining a studio shot, the size of that studio gets larger, and larger, and larger as they walk.
Title: Re: Stereo parallax
Post by: cjameshuff on September 21, 2014, 11:37:52 PM
The clip I remember is...I think it was "House Rock," but I can't remember the flight. Shot from the parked rover, the astronauts go walking down a gentle slope towards a boulder. And keep walking. And keep walking. Because the boulder is the size of a small house. And if you are imagining a studio shot, the size of that studio gets larger, and larger, and larger as they walk.


https://www.hq.nasa.gov/alsj/a16/a16.house_rock.html
Title: Re: Stereo parallax
Post by: ka9q on September 22, 2014, 02:24:27 AM
Can anybody explain lens geometry to me? I know the Biogon lenses were good, but I don't know what model is considered ideal. Any lens maps (part of) a spherical scene onto a flat imaging surface, so for all of a wide-angle image of a scene at a given distance to be in focus the effective focal length of the lens has to be greater at the edges of the image. That implies that a given angular separation will appear larger on the flat film at the edges of the image than at the center.

Am I right that it's this simple? Or does the lens do more?
Title: Re: Stereo parallax
Post by: cjameshuff on September 22, 2014, 07:44:52 AM
Can anybody explain lens geometry to me? I know the Biogon lenses were good, but I don't know what model is considered ideal. Any lens maps (part of) a spherical scene onto a flat imaging surface, so for all of a wide-angle image of a scene at a given distance to be in focus the effective focal length of the lens has to be greater at the edges of the image. That implies that a given angular separation will appear larger on the flat film at the edges of the image than at the center.

Am I right that it's this simple? Or does the lens do more?

There are many different ways to do it, just as there's many ways of projecting a globe onto a flat map. Most lenses try to imitate a pinhole camera, which behaves as you describe, keeping lines straight but having angular sizes exaggerated away from the center. Other lenses are designed to preserve angular size or area, and will produce curved images of straight lines, but tend to be better suited to wide angles.

http://en.wikipedia.org/wiki/Fisheye_lens#Mapping_function

And of course, real lenses have to work with a light field manipulated through a series of lenses and can only approximate these.
Title: Re: Stereo parallax
Post by: JayUtah on September 22, 2014, 07:39:13 PM
Can anybody explain lens geometry to me? I know the Biogon lenses were good, but I don't know what model is considered ideal. Any lens maps (part of) a spherical scene onto a flat imaging surface, so for all of a wide-angle image of a scene at a given distance to be in focus the effective focal length of the lens has to be greater at the edges of the image. That implies that a given angular separation will appear larger on the flat film at the edges of the image than at the center.

Am I right that it's this simple? Or does the lens do more?

The Biogon lens tried to more faithfully replicate life by pushing the most notable distortion toward the edges of the frame -- mostly in the corners.
Title: Re: Stereo parallax
Post by: AstroBrant on September 23, 2014, 01:32:34 AM
The clip I remember is...I think it was "House Rock," but I can't remember the flight. Shot from the parked rover, the astronauts go walking down a gentle slope towards a boulder. And keep walking. And keep walking. Because the boulder is the size of a small house. And if you are imagining a studio shot, the size of that studio gets larger, and larger, and larger as they walk.

That one was an excellent demonstration of how deceiving size and distance can be on the moon. One of the several videos I would like to make is one which would show lunar scenes and ask the viewer to guess how far away or how big certain features are. I've already done some of the calculations and have images that I have added objects to, like an aircraft carrier, a school bus, and the New York city skyline.

That House Rock clip will be in my video. I also have some pictures from a rover traverse sequence where two rocks seem to be about the same size and at about the same distance. The next few frames will show us approaching and passing one of the rocks while the other is still a long way off.
Title: Re: Stereo parallax
Post by: nomuse on September 23, 2014, 03:17:44 AM
Not completely restricted to the Moon. I had the experience of walking along the floor of Death Valley. No plants, nothing to take scale off of, extremely dry air and little in the way of aerial perspective. I could still get a general sense of how far it was to the rock formation I was heading for, but only within a magnitude (I guessed almost that low!)
Title: Re: Stereo parallax
Post by: ka9q on September 23, 2014, 04:05:12 AM
That one was an excellent demonstration of how deceiving size and distance can be on the moon. One of the several videos I would like to make is one which would show lunar scenes and ask the viewer to guess how far away or how big certain features are. I've already done some of the calculations and have images that I have added objects to, like an aircraft carrier, a school bus, and the New York city skyline.
Have you seen the IMAX film Magnificent Desolation? Tom Hanks, who narrated, did something very similar with images from my favorite Apollo mission, Apollo 15. It's my favorite because of the dazzling scenery, especially Hadley Rille. To make this point about scale, he stuck the Statue of Liberty to scale down in the rille.

It wasn't just us looking at TV and photos who had trouble judging scale on the moon. The astronauts themselves were often fooled.

Title: Re: Stereo parallax
Post by: AstroBrant on September 30, 2014, 10:35:58 PM
(snip...)
Have you seen the IMAX film Magnificent Desolation? Tom Hanks, who narrated, did something very similar with images from my favorite Apollo mission, Apollo 15. It's my favorite because of the dazzling scenery, especially Hadley Rille. To make this point about scale, he stuck the Statue of Liberty to scale down in the rille.

It wasn't just us looking at TV and photos who had trouble judging scale on the moon. The astronauts themselves were often fooled.

No, I haven't seen it. I'll have to check it out. Darn! Every time I think I have an original idea for something I find out somebody else already did it. Oh well, at least I'll know not to use the Statue of Liberty.

On this matter of parallax measurement and lens distortion I noticed something just a couple of days ago. I found pictures of the earth taken by Gene from Station 2, (near Nansen, at the base of South Massif). He did a pan from the same place. I thought it would be fun to make my own pan and add the earth above it. I just used MS Paint, but I was amazed at how badly some of the pictures lined up. Some of this could be attributed to the changing of the vertical angle of the camera from one picture to the next, but there were other problems, like how vertical distances between two objects near the right edge of one picture were quite different from their separation as they appeared near the left edge of the next picture. These must be caused by lens distortion. Since they are the same objects and the pictures were taken from the same spot, it couldn't be due to parallax or perspective foreshortening.

I wonder if the people who have assembled pans for ALSJ run into this problem so much that it becomes a matter of routine for them, and if they have to skew pictures to make objects line up where they join them together. I wonder if they even may have to vertically compress the top portion of some pictures and stretch the bottom, and vice versa.
 
This may be a good point in my video.
Title: Re: Stereo parallax
Post by: ka9q on October 01, 2014, 06:15:01 AM
I can't really speak to the topic of lens distortion, but I know there are programs that will assemble panoramas for you while correcting for geometric distortion and/or remapping the composite image to a different projection.

Regarding visual size comparisons for Hadley Rille, an obvious one that I haven't actually seen yet is to put it and the Grand Canyon either side-by-side or on top of each other to proper scale, of course. You would have to find a picture of the Canyon with a similar perspective to one of Apollo 15's shots of the Rille. We visited the Canyon two years ago and took tons of pictures from both North and South Rim I'd be willing to contribute.


Title: Re: Stereo parallax
Post by: Zakalwe on October 01, 2014, 01:02:50 PM
I can't really speak to the topic of lens distortion, but I know there are programs that will assemble panoramas for you while correcting for geometric distortion and/or remapping the composite image to a different projection.



There's plenty of stitching programs out there. Photosynth is very good, as is the free Microsoft Image Composite Editor.
http://research.microsoft.com/en-us/um/redmond/groups/ivm/ice/
https://photosynth.net/

Photoshop also does a very good job (use the Photomerge tool).