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M_Welander
2002-Jun-03, 05:59 PM
While I was browsing through Cosmic Dave's site for the image of the astronauts with different shadow length, I found another image he claims to be proof of the landing being filmed in a studio or another controlled environment.

I know this has been discussed before, so I'll just write a quick note about why he thinks so, and why it is wrong.

Cosmic Dave claims that the front of the astronaut can not be lit by the sun, since the sun is behind him.

The reason he is wrong is because he has forgotten to take into account the scattering of the light from the lunar surface.

To prove this, I have created two CG images of the scene. One is made with the significant error (the same Cosmic Dave made) of ignoring the scattering, and the second use correct scattering.

Please compare them with the actual photo to decide which one is most correct.

http://www-und.ida.liu.se/~matwe042/moon/orgrad.jpg
Actual photo

http://www-und.ida.liu.se/~matwe042/moon/scattering.JPG
CG with correct scattering

http://www-und.ida.liu.se/~matwe042/moon/noscattering.JPG
CG without scattering

The second image is a simulation of what an astronaut would actually look like on the moon in this lighting situation.

Of special interest is the relation between the scattering effect seen on the front of the astronaut, and in the shadow. Cosmic Dave claims that the front of the astronaut can not be lit when the shadow is dark. As you can see, the shadow is not entirely dark, but it is significantly darker than the front of the astronaut. The same is true in the CG simulation. The reason is of course that a lot more light is scattered from the lunar surface onto the astronaut, than from the surface and back to the surface.

Scene file to prove this is not a fake (http://www-und.ida.liu.se/~matwe042/moon/MoonRad.zip)

JayUtah
2002-Jun-03, 07:02 PM
Cosmic Dave has copied most or all his arguments from David Percy, Mary Bennett (whom he claims to know) and Bart Sibrel. He has apparently expended very little original thought toward his arguments.

David Percy categorically denies that reflected from the lunar surface has any photographically significant effect on lunar photography. Of course he couldn't be any more wrong, but that doesn't bother Cosmic Dave.

The albedo of the lunar surface is, at the lowest measurement, 12%. This is slightly less than the standard 18% gray card used by photographers. Percy claims it's the same albedo as fresh asphalt, which is also incorrect. Fresh asphalt has an albedo of about 4%, while aged asphalt has the albedo of 12% or higher.

In any case, the effect of sunlight reflecting off aged asphalt is quite photographically significant.

Further, the lunar surface reflects light most strongly back toward the direction from which the light came, irrespective of the angle of incidence. This is not an effect modelled in most computer-based rendering systems. But it does answer why down-sun surfaces should be adequately filled.

M_Welander
2002-Jun-03, 07:08 PM
I see. You're quite right, I have not considered the angle of the scattered light. I doubt it would make much difference in this image, but still, I guess it's important.

However, angle or no angle, I hope my images prove that scattering is the reason why the front side of the astronaut, while in shadow, is significantly stronger lit than the shadow on the ground. Had a fill light been used on a stage to light the front of the astronaut, the shadow on the ground would have been lighter, too.

JayUtah
2002-Jun-03, 07:16 PM
I understand you perfectly when you talk about diffuse reflection from the lunar surface. And I can translate that to empirical practices in the photo studio for our friends who think that way too. The zero-phase effect is something that's more pronounced on the moon than on earth.

You could duplicate it in the computer, but you would have to micromodel the texture of the surface and provide for diffuse interreflection to adjust to that texture. That's a radiosity solution, as I'm sure you recognize, and to do a diffuse interreflection render on a micromodeled texture would be more CPU time than anyone would care to expend. That's why it's simply approximated as a general effect.

David Percy purports to be an "award-winning photographer," but so far all the other photographers I've consulted (myself included) do little more than laugh at his theories.

cosmicdave
2002-Jun-03, 07:35 PM
If this light scattering and surface reflection is so intense, why isn't the Astronauts shoes lit up, considering that they are actually standing on this bright really reflective surface?

Now perhaps someone could try and explain the large pan shot on my site which shows the LEM, satellite dish, shadow of the cameraman and the American flag. All the shadows converge towards a central spot which seems to have more concentrated white light within it (even though this area of lunar surface is actually in a dippy). Now I know that at first sight some of you will simply say that its because of this dippy in the ground that the shadows are drawn into that area, but if we take the shadows of the LEM and dish as a reference, the flag shadow should follow suit and fall from SW to NE as should the astronauts shadow.

That will take a little bit of explaining, and which I hasten to add has never been answered by any sceptic which has written to me or debated my page.

M_Welander
2002-Jun-03, 07:48 PM
First of all, cosmicdave, I'd like to say 'Hi!', since we haven't talked before, and also thank you for considering my input in the discussion.

The reason why the shoes are not as bright as the body of the astronaut is exactly the one you said yourself - namely that the shoes "are actually standing on this bright really reflective surface", while the body is higher above it. Thus, from the point of view of the body the ground plane will take up a larger angle than it will from the point of view of the shoes. As a result, more light will be scattered from the surface onto the body than onto the shoes.

While this is a well known effect in the CG community, it might not be something that everyone know. If you want, I could provide you with attitional CG material to show it properly, or you could simply do the following experiment (although this is not *exactly* the same situation):

Take a room lit through a window. Now look at a corner of the room on the wall with the window. You'll notice that the corner is darker than the wall. That is because the corner is closer to the other wall than the wall itself is, and thus does not get as much reflected light.

I'm afraid I'm not entirely sure of which image on you're site you're talking about. I thougth I had looked at them all, but obviously I have missed something (your site is rather large, and a little bit hard to grasp for a new reader like me). Could you please help me here and point out exactly what it is I should look for? If you can, I'd be most happy to consider the lighting situation and see if it is possible to duplicate it on a lunar situation, or not.

(Corrections due to the fact that English is not my native language...)

<font size=-1>[ This Message was edited by: M_Welander on 2002-06-03 15:51 ]</font>

infocusinc
2002-Jun-03, 08:48 PM
Dave,

If you want to see an example of why the boots are darker that the top portion of an astronaut just look at the last photograph that in Jays post of photographic examples. In fact I even made this exact comment in a post after viewing his examples. I can recreate the exact effect as many times as you wish in my photo studio or outside in sunlight. Do you need addition examples so you can understand this simple effect?

Can you give us the image number of the image you referenced in your post? My first thought without seeing the image is that perspective is what may be causing the shadows to behave the way you describe but I will need to see the image to be sure. It is a very common misconception to think that all the shadows in a photograph taken in sunlight will always appear to run parallel.

JayUtah
2002-Jun-03, 09:39 PM
If this light scattering and surface reflection is so intense, why isn't the Astronauts shoes lit up, considering that they are actually standing on this bright really reflective surface?

First, because the shoes are matte rubber and the suits are highly reflective Chromel. Second, because the closer an object is to the actual surface, the less scatter it receives.

Go outside and find a flat space. Take a look around and see how much of the ground you can see. You can probably see several hundred feet in any direction.

Now lay down and get your eye right down near the ground. That's the "shoe's eye view" of the surface. How much of the surface can you see? Probably only a few -inches in either direction.

Now imagine you're the toe of a boot on an astronaut facing down-sun. You can't see behind you. The only part of the lunar surface you can see is the part that's in shadow.

Now imagine you're the crest of an astronaut's helmet, again facing down-sun. Six feet up in the air, how much of the lunar surface would you be able to see? Probably a whole lot, and not just the portion covered by the shadow. And thanks to the behavior at zero phase angle, the portion you could see out at the tip of the astronaut's shadow would be very bright.

Pretending you're these different items is crucial, because the amount of lunar surface you can "see" from any point on the astronaut's suit will dictate how much diffuse reflection will fall on that point.

Now perhaps someone could try and explain the large pan shot on my site ...

Sure, but in a different thread. I'm tired of your constant subject changes.

That will take a little bit of explaining, and which I hasten to add has never been answered by any sceptic which has written to me or debated my page.

I'm really getting sick of this same old rhetoric. You say, "The skeptics told me this," while you can't point to where it was said, or what nick you posted under when they said it. More likely you misunderstood what was said. You seem to have a serious problem reading with comprehension.

Then you say, "The skeptics can't answer this one," when in fact if you just take the step of asking, you'll get your answer.

You've deployed several of these "can't answer this" arguments, and when they're answered you just throw out speculative handwaving and change the subject.

Do you, at any time, plan on carrying any one topic to completion? Do you at any time foresee the need to concede any of your points?


<font size=-1>[ This Message was edited by: JayUtah on 2002-06-03 17:39 ]</font>

Ian R
2002-Jun-04, 03:39 AM
http://www.ufos-aliens.co.uk/goodphoto.gif



I believe that this is the particular picture that Cosmic Dave has been referring to. It is a panoramic mosaic of several individual photographs that were taken during the Apollo 12 mission. The composite's field of view, from left to right is at least 90 degrees, so it is unreasonable to expect that the shadows should be pointing in a similar direction. The optical illusion which makes the four shadows look as if they are converging to a point on the lunar surface is called perspective. Sound familiar?



Oh, and the location to which all the shadows seem to be pointing to is known as the vanishing point. Stand in the middle of a long and straight railway line and see how the two rails appear to converge to a point on or near the horizon. Exactly the same principles involved, just that a panoramic view greatly magnifies the apparent optical effect of perspective.



The white light just above the astronaut's shadow is a common lunar phenomenon known as the zero-phase effect. See Jay's Apollo 11 page (http://www.clavius.org/a11rear.html) for photographs demonstrating that the 'halo' is a perfectly natural occurence.



(corrected faultly link)

<font size=-1>[ This Message was edited by: Ian R on 2002-06-03 23:46 ]</font>

jrkeller
2002-Jun-04, 04:26 AM
This looks like a good project to do on some of the software that I use for radiative heat transfer. What surface properties did you use? Do you use a ray tracing technique?

I figure I would use a 10% reflectance for the lunar surface.

By the way, your English is pretty good. A lot better than my second language of German.



<font size=-1>[ This Message was edited by: jrkeller on 2002-06-04 00:27 ]</font>

M_Welander
2002-Jun-04, 10:18 AM
Thank you. I was just using a very simple Monte Carlo radiosity solution. The surface properties were simply set up to aproximate the photographic image, and are not scientifically accurate. They do, however, work well enough to show the difference between an image where you take into account the light scattering, and one where you forget to do so.

jrkeller
2002-Jun-05, 05:12 PM
Using a completely different code, a thermal radiation code, I was pretty much able to duplicate your results.

Here's what I did.

I made a very simple, stick figure model of a suited astronaut 6ft 6 inches tall (about 2 meters)

The outer surface of the suit absorbs 30% of the sunlight and of course reflects 70%

The model is then placed on a flat lunar surface 100 ft by 100 ft (32m x 32m). The lunar surface absorbs 90% of the light sunlight and of course reflects 10%.

I used a solar angle of 10 degrees above the horizon and the sun is directly begin the stick figure. I did not include any Earth illumination.

The results.

First of all, the boots reflect almost no sunlight. Above knee level, the illumination of the suit is fairly constant, but the helmet and shoulder areas are the brightest.

My predictions show that the lunar surface reflects approximately 23.5 W/m2 while the upper portions of the suit reflect 7 W/m2. For a ratio of 3.35.

When I made the lunar surface 100% absorbing, the front part of the suit no longer is visible.

To me it is obviously clear that the front part of the suit can be seen, even with the sun directly behind.

<font size=-1>[ This Message was edited by: jrkeller on 2002-06-05 13:33 ]</font>

M_Welander
2002-Jun-05, 05:55 PM
This is highly interesting, and, of course, completely consistent with how things should be if the moon landing did in fact take place.

I'm wondering what would have happened if someone had tried to duplicate the scene with two stage lights, as cosmicdave claims is the case here. My guess is that you'd end up with some pretty weird shading situations that are inconsitent with the image. I don't know, so it's just a general feeling I have.

Valiant Dancer
2002-Jun-05, 06:07 PM
On 2002-06-03 13:59, M_Welander wrote:
While I was browsing through Cosmic Dave's site for the image of the astronauts with different shadow length, I found another image he claims to be proof of the landing being filmed in a studio or another controlled environment.

I know this has been discussed before, so I'll just write a quick note about why he thinks so, and why it is wrong.

Cosmic Dave claims that the front of the astronaut can not be lit by the sun, since the sun is behind him.

The reason he is wrong is because he has forgotten to take into account the scattering of the light from the lunar surface.

To prove this, I have created two CG images of the scene. One is made with the significant error (the same Cosmic Dave made) of ignoring the scattering, and the second use correct scattering.

Please compare them with the actual photo to decide which one is most correct.


The second image is a simulation of what an astronaut would actually look like on the moon in this lighting situation.

Of special interest is the relation between the scattering effect seen on the front of the astronaut, and in the shadow. Cosmic Dave claims that the front of the astronaut can not be lit when the shadow is dark. As you can see, the shadow is not entirely dark, but it is significantly darker than the front of the astronaut. The same is true in the CG simulation. The reason is of course that a lot more light is scattered from the lunar surface onto the astronaut, than from the surface and back to the surface.

Scene file to prove this is not a fake (http://www-und.ida.liu.se/~matwe042/moon/MoonRad.zip)



On the old board, someone (and again the name escapes me) posted a number of pictures where, using clay, an astronaut action figure, a camera, a LEM model, string, and sheets of paper, the individual was able to reproduce the exact same lighting anomalies shown in the Apollo moon shot. This proved (in pretty graphic measure) that the lighting anomalies were actually normal and the absence of them would indicate fraud.

That tended to shut up the P-word for about two weeks. Then he pulled mini-anomilies out of his posterior. The rest is BABB history and caused the formation of a benevolent collection of P-word Anonomous members. (myself included.)

_________________
Valiant Dancer

<font size=-1>[ This Message was edited by: Valiant Dancer on 2002-06-05 14:08 ]</font>

Jim
2002-Jun-05, 08:19 PM
On 2002-06-05 14:07, Valiant Dancer wrote:
On the old board, someone (and again the name escapes me) posted a number of pictures where, using clay, an astronaut action figure, a camera, a LEM model, string, and sheets of paper, the individual was able to reproduce the exact same lighting anomalies shown in the Apollo moon shot. This proved (in pretty graphic measure) that the lighting anomalies were actually normal and the absence of them would indicate fraud.


Ian Goddard?

His site is now gone, but the BA is hosting the image page here http://www.badastronomy.com/bad/tv/iangoddard/moon01.htm.

cosmicdave
2002-Jun-06, 09:06 PM
Interesting to see that the experiment and examples were carried out using a lamp and not natural light.

pvtpylot
2002-Jun-06, 09:15 PM
On 2002-06-06 17:06, cosmicdave wrote:
Interesting to see that the experiment and examples were carried out using a lamp and not natural light.

And in your expert opinion, what difference would that make?

AstroMike
2002-Jun-06, 09:20 PM
On 2002-06-06 17:06, cosmicdave wrote:
Interesting to see that the experiment and examples were carried out using a lamp and not natural light.

You missed the point. They were carried out with one light source, not multiple. If you want to see they can be done with sunlight, then maybe you should go outside once and a while.

M_Welander
2002-Jun-06, 09:21 PM
Also note that the CG examples were created using natural sun light, not artificial light.

And, as you said, what difference would it make? None, of course. Light rays travel in a straight line (forget relativity here) no matter if the source is the sun or a lamp.

jrkeller
2002-Jun-06, 10:29 PM
CD,

Actually, my numerical model used a solar spectrum and a parallel light source.

In reality there is some spreading from the sun.