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Post by JayUtah on Oct 1, 2005 15:29:22 GMT -4
Are you saying that the mountain is not 3kms away from the LM?
No, I'm just saying that you don't need to take anyone's word for it that some feature is some distance away. You can look it up for yourself. I don't mean that to sound dismissive; I'm saying that I'm confident that I don't need you to trust my opinion or anyone else's in order to draw a conclusion that I would agree with.
He said also that a ridgeline hides the foreground. I find that absurd
I don't, and I live in the mountains. The Salt Lake Valley where I live shares the same general geography as the Taurus Littrow valley on the moon. I see exactly these same effects twice a day on my way to and from work.
What I think he's trying to say is that the valley floor may look relatively flat in these photos, but it isn't. The contours of a valley floor tend to get lost amid mountains. In lunar photos taken on the maria the horizon marks the boundary between gray ground and black sky. But it's hard to tell how far away it is. If you have those gentle undulations, the horizon line you see may only be a hundred meters away, and you'd never know it from the photo.
When that happens in mountainous terrain, the distance between an intervening rise and a distant mountain may not be apparent. You might think you can see all the terrain from where you're standing all the way up to the base of the mountains and up the side. But not always.
There's a spot on Interstate 15 near the south end of the Salt Lake valley from where you can see an interesting view: The "nearby" horizon is a line of rooftops about 12 miles away -- it's a neighborhood that sits atop a very gentle hill. Over the tops of the roofs I can see the distant Oquirrh Mountains that are nearly 20 miles away. If I were to take a picture of this, it would look like many of the Apollo 17 photos. But you wouldn't be able to see the 8 miles of stuff that lies between that hilltop neighborhood and the mountains. And that invisible portion of the valley contains, among other things, an entire wing of the Utah Air National Guard and their air base.
Now the effect isn't as dramatic because the horizon is composed of house roofs. We all know how big a house is, so this gives us some indication of actual distance. Even in a photograph you'd be able to say, "Hey, that demarcation is really only a few miles away because of the apparent size of the houses." But in pure landscape photography, like that done on the moon, you get no such cues. And you don't get any of the other traditional depth cues such as haze attenuation. That's why it's very difficult to get distance information in Apollo photographs -- all the depth cues are missing.
Parallax is just about the only remaining cue. It's actually a very powerful one. Sit up straight and look straight ahead. Focus on a nearby object with a more distant background. Now turn your head slowly in both directions while keeping your eyes focused on your subject. You can see it appear to shift against the background. That's a parallax depth cue; even that simple motion of your head creates a different point of view. That's because your eyes actually lie a few inches off your head's rotational axes. Even very slight, involuntary motion of your head lets you acquire 3D information this way. This works even if you only have one good eye.
In photography don't get this information. But if you have two or more photographs taken from a similar but not identical point of view, you can use parallax shifts to gauge roughly the distance to objects in the photo. If you build up a good photogrammetric basis you can actually recover accurate 3D information. Architects and engineers use these methods to measure things photographically. I was actually surprised to see that the demarcation between the dark foreground and the light background in the Apollo 17 photos we're discussing exhibited such drastic parallax. I would have guessed that the demarcation was actually much farther away from the photographer -- say a kilometer or two. Now the degree of parallax suggests that it may be only dozens of meters away.
I don't have the basis to compute this, but the point is simply that the "intervening rise" theory is well-established in human experience, and we can get a ballpark estimate of its distance using some standard methods of photographic analysis.
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Post by lordoftherings on Oct 1, 2005 16:04:09 GMT -4
Jay, dear, i can see the base of the mountain, with land around it. It is not just a ridge line from topography. It just is very absurd that it hides over 3kms of land. I can see what you said, I have seen photos of this phenomena, but I don't think it fits here. And the second photo, Oh, just don't remind me of it. It is supposed to be 2kms far from the LM, i.e roughly 5kms from the mountain, the land is flat, everything is very clear in it, yet , the astronaut is 10 steps away from the mountain. I don't know, maybe you can see something I can't see. Anyways, don't write newspapers plz, you should have been good at composition classes , but I don't have the guts to read so much. So plz be consise regards
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Post by JayUtah on Oct 1, 2005 18:53:56 GMT -4
It just is very absurd that it hides over 3kms of land. I can see what you said, I have seen photos of this phenomena, but I don't think it fits here.Why not? ...the land is flat...How would you know, in the absence of cues? ...yet , the astronaut is 10 steps away from the mountain.No. As I mentioned, the normal depth cues are missing in Apollo photography. Most of them are missing in all photography, but even more are missing in Apollo photographs. It is difficult even for experts to judge distance in them. In fact the astronauts reported it was difficult for them to judge distances while they were there. Parallax becomes ineffective past a few hundred meters. Then we rely on apparent size of recognizable objects and comparative haze attenuation. This is well-studied. When there are no recognizable objects, such as when one is in a purely desolate environment, it is difficult to use their apparent size as cues. The eye is highly attuned to differences in color value density. It's unconscious to use those as depth cues. There's a great video clip from one of the missions where the astronauts are in the foreground of the shot and they're contemplating going out to visit this rock we can see in the background. It's called House Rock. And the camera stays on the astronauts the whole time as they're walking out to it. As they get very small in the distance and walk seemingly forever, you suddenly get the notion that the rock is very large and very far away, much more so that you would have thought from the initial view. It's as big as a house, which is why it's called that. www.hq.nasa.gov/office/pao/History/alsj/a16/video16.html#houserock (watch the first couple of clips) The other common misleading cue in Apollo photography is the rounded shape of the mountains. It makes them look like mounds or hills would look like on Earth. This gives you the impression that they're nearby and short. ...So plz be consiseWell, I'm thorough. That's just the way I am. I do have a tendency to repeat myself, which I'm trying to help. But when I discuss something, I do it thoroughly so there's little mistaking what I mean.
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Post by nomuse on Oct 1, 2005 19:32:25 GMT -4
I've had this experience on Earth. I drove out onto the floor of Death Valley, meaning to do a little hiking around. Drove until it looked like I was getting up on the rocks at one end of the valley and stopped (didn't want to drive into anything bad). Got out, grabbed my canteen, and started walking towards the nearby rocks. Walked towards the nearby rocks. Walked some more towards the nearby rocks. After about an hour of this the rocks hadn't gotten any nearer. I backtracked to the car at that point, checked my maps, and realized my eyes had misjudged -- to the order of several kilometers.
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Post by PhantomWolf on Oct 1, 2005 22:20:56 GMT -4
I think I might have mistaken the images you were talking about lordoftherings, mostly because every time I've tried going to NASAscam, it's been out of bandwidth and so was going on memory and other's repsonses. I was thus assuming you were talking at the images also used by Jack White where the Mountian "grows." Yet above you seem to be talking about the "missing LM" that star introduced a way back. In that one the slight ridgeline is very hard to see in the first image, but there is another image taken from a slightly different angle that clearly shows not only the ridge, but most of the ground you can't see in the initial photo too. The second photo isn't taken another 2 km back from the mountain, thus having the LM between the photographer and the mountain, it is off to the side, to the west if I'm recalling right. That means the mountain is still about 3km away from the photographer, but the LM is 2 km away to the left of the photo. I'll see if I can locate the transvere map as well, that is what I did the measurements off of.
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Post by PhantomWolf on Oct 1, 2005 22:26:50 GMT -4
I have a feeling that Buzz said in their debriefing that there was a boulder field at the Apollo 11 landing site with what they thought were 2-3 feet tall boulders, around about 100m from the LM, so they decided to head over and look at them. Having walked the 100m they discovered that the boulders were still 2-3 feet tall and still in the distance, so they gave up and headed back to the LM. I think they decided that the field really had 8-10 feet high boulders and was about 1-2km away
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Post by nomuse on Oct 1, 2005 22:57:50 GMT -4
Yup. It's a mistake that's harder to make on Earth...most places on Earth have various scale/distance references.
That's why I think my Death Valley experience is informative. Unlike most of the places I'd hiked or done orienteering in, there are few marks of civilization, the shapes are very fractal (meaning you really can't tell the difference between a rock wall hundreds of feet away and a mountain range thousands of feet away), and the air is extremely dry and still -- meaning a lot less of the distortion, haze, and color shifts we are used to seeing.
Which is to say; many of the same elements that makes the Moon so difficult to guess distances and sizes on.
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Post by JayUtah on Oct 1, 2005 23:16:58 GMT -4
I remember taking a series of photos in the Sahara desert of what I thought to be rolling terrain. The photos instead were simply flat, lifeless depictions. You could not see the tops of the ridges. There was no foliage, no buildings, nothing to help the eye pick out those features of depth. Tan on the bottom and blue on the top.
The same was generally true of Mars photos until stereo photography equipment was sent. Then the previously hidden contours of Mars were revealed. You can do this with Apollo photographs since there were many stereo pairs taken manually. There are some anaglyphs out there made from Apollo 70mm photos.
I've dealt with space photography for many years, and these 3D renditions really opened my eyes. The surfaces of these planets and moons are far lumpier than the photos initially show.
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Post by PhantomWolf on Oct 2, 2005 1:34:27 GMT -4
Yeah, really it's quite amazing. The Images of Soney Mountain that were referanced above, and which has all the links to the images and stuff in my post at the end of the "Armstrong" thread, really is a classic example. If you aren't aware of the distances and sizes, and just look at the salute photo, it is very easy to assume that the "hill" is just there. You can just see the line of the ridgeline that the Lander sits on, but with the curved top and no 3D ability, it looks like Stoney is right next to the LM, not 3 km away. It's only when you look at the Panarama which is taken down on a flatter section that you can really see exactly how far away the mountain actually is.
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Post by lordoftherings on Oct 2, 2005 4:43:20 GMT -4
What we are questioning is the Apollo missions. we can't say it is bcz Armstrong said the rock is so and so then it is right.
If the mountain is still 3kms away, then, it certainly looks smaller in the other photo. This phenomena of "ridgelines" is very much repeated in the Apollo photos, which makes it difficult to believe that in every mountain photo there is a ridgeline.
Anyhow, I want to go back to Bob's experiment. You said that the backdrop in your photos did get bigger. I don't see that. If you hide the LMs in both photos and compare the mountains. One of them is small where it should be big, as the LM got bigger
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Post by PhantomWolf on Oct 2, 2005 6:00:35 GMT -4
When I talk about a ridgeline, what we are really meaning is an hill or bump which hides what's behind it. They are incredibly common on Earth too. The difference between eEarth and the Moon is that on Earth we tend not to notice them because there are trees, houses, power poles and so on to give us the distances involved. There is also a "blueing" effect of the atmosphere due to haze and dust. I live right next to a mountain and when we have a lot of haze and dust in the air it is so pale you can hardly see it gainst the sky, but on days when there is virtually pure air, the greens are so apparent it seems that the mountain is looming over you. This and knowing that the green I'm seeing are really tree gives the impression of the real distance. On the moon you don't have that. The astronauts only had their eyes to judge distances, we have even less with the photos because a photo removes depth. That means that when a photo is taken of an area with a rise in it, then anything that is hidden by the rise is simply lost. We have know cues to determine how far away the ground we see beyond that rise is. And worse, because the colours are very similar, it's often very hard to determine where the actual top of the hills are to figure out what is being hidden and what isn't. One of the things a lot of the Proponents make is to claim that anyone can look at a photo and interrupt it. That's not my experience. Pictures have surprised me time and time again where depth and distance is conserned. I have looked at hundreds of Apollo pictures and probably about half that number of Mars images, and yet when I see them in 3D with stereo pairing, it shocks me the actual depths. One Mars image I was looking at was of what appeared to be a shallow river valley. With the 3D view the image changed into a very deep canyon, probably deeper then the Grand Canyon. I was so surpirised I spent about 30 mins comparing the 2D and 3D image to get my head around it.The 2D image just didn't show what was there. This is one of the problems I have with margamatrix. He looks at a photo and dismisses it without knowing what he's really loking at. Esentially he doesn't see what he thinks he should see nd so he claims it's wrong. The trouble is that photos don't show us what we expect to see, until we understand why photos show what they do. It's a case of "This is not a Pipe." The photo isn't what was there, it's a 2D representation of a 3D event. This means that things won't act in exactly the way we expect them and unless we understand the rules, we'll make mistakes. Consider the two images in my "Armstrong" post: Image 1Image 2Now at first glance we can be tempted to claim that Stoney Mountain is the same in both, but take a closer look at Image 1. If you look at the top of the Mountain, about a quarter of the way along from the right side of it, there is a bright crater. There are two more of them almost directly on a line btween the bright top crater and the middle of the astronaut's forearm. This line makes about a 35° angle with the base ofmthe mountain. Now have a look at Image 2, the salute image. Again we can identify the 3 craters, but this time only two are in a line, the line being at about 80° from the baseline and the middle crater is under, actaully slight to the right of, the top crater. That these craters have moved quite substainally shows that the mountain truely is a 3D object. They have moved because of parallax. By knowing a bit about parallax we can guess at the direction of movement, with more information, we could even get a distance. The direction is to the right of the LM, which does match the positions of the places the Flag Crater photo was taken.
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Post by lordoftherings on Oct 2, 2005 7:22:13 GMT -4
When I talk about a ridgeline, what we are really meaning is an hill or bump which hides what's behind it. They are incredibly common on Earth too. The difference between eEarth and the Moon is that on Earth we tend not to notice them because there are trees, houses, power poles and so on to give us the distances involved. So they should be noticeable on THE MOON, BUT THEY ARE NOT. There is also a "blueing" effect of the atmosphere due to haze and dust. I live right next to a mountain and when we have a lot of haze and dust in the air it is so pale you can hardly see it gainst the sky, but on days when there is virtually pure air, the greens are so apparent it seems that the mountain is looming over you. This and knowing that the green I'm seeing are really tree gives the impression of the real distance. On the moon you don't have that. The astronauts only had their eyes to judge distances, we have even less with the photos because a photo removes depth. That means that when a photo is taken of an area with a rise in it, then anything that is hidden by the rise is simply lost. We have know cues to determine how far away the ground we see beyond that rise is. And worse, because the colours are very similar, it's often very hard to determine where the actual top of the hills are to figure out what is being hidden and what isn't. One of the things a lot of the Proponents make is to claim that anyone can look at a photo and interrupt it. That's not my experience. Pictures have surprised me time and time again where depth and distance is conserned. I have looked at hundreds of Apollo pictures and probably about half that number of Mars images, and yet when I see them in 3D with stereo pairing, it shocks me the actual depths. One Mars image I was looking at was of what appeared to be a shallow river valley. With the 3D view the image changed into a very deep canyon, probably deeper then the Grand Canyon. I was so surpirised I spent about 30 mins comparing the 2D and 3D image to get my head around it.The 2D image just didn't show what was there. This is one of the problems I have with margamatrix. He looks at a photo and dismisses it without knowing what he's really loking at. Esentially he doesn't see what he thinks he should see nd so he claims it's wrong. The trouble is that photos don't show us what we expect to see, until we understand why photos show what they do. It's a case of "This is not a Pipe." The photo isn't what was there, it's a 2D representation of a 3D event. This means that things won't act in exactly the way we expect them and unless we understand the rules, we'll make mistakes. But again, these are NASA photos, the 2D and the 3D. And we are questioning them. Consider the two images in my "Armstrong" post: Image 1Image 2Now at first glance we can be tempted to claim that Stoney Mountain is the same in both, but take a closer look at Image 1. If you look at the top of the Mountain, about a quarter of the way along from the right side of it, there is a bright crater. There are two more of them almost directly on a line btween the bright top crater and the middle of the astronaut's forearm. This line makes about a 35° angle with the base ofmthe mountain. Now have a look at Image 2, the salute image. Again we can identify the 3 craters, but this time only two are in a line, the line being at about 80° from the baseline and the middle crater is under, actaully slight to the right of, the top crater. That these craters have moved quite substainally shows that the mountain truely is a 3D object. They have moved because of parallax. By knowing a bit about parallax we can guess at the direction of movement, with more information, we could even get a distance. The direction is to the right of the LM, which does match the positions of the places the Flag Crater photo was taken. what has this to do with out case?
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Post by PhantomWolf on Oct 2, 2005 7:46:49 GMT -4
what has this to do with out case? Well in talking about how things can appear closer than they really are, and not being able to guess the distance to an item in a lunar photo, it's a good example.
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Post by lordoftherings on Oct 3, 2005 4:34:22 GMT -4
Hey Bob, I am still waiting your answer about the backdrop. You said when the LM got gigger, the backdrop got bigger, but it doesn't seem so. It looks smaller than the other one, if you hide both LMs and compare them.
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Post by nomuse on Oct 3, 2005 5:01:21 GMT -4
LordOfTheRings....match the fiducials, first, to make sure you don't have one image at a different resolution. And don't trust eyeballing it; I KNOW you've seen some of the popular optical illusions around. Assemble them as PhotoShop layers so you can make a direct comparison. www.michaelbach.de/ot/ang_poggendorff/index.html
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